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Baffling engine issue - runs for 6 minutes, dies, but then starts right back up
#1
W
wesw
W
wesw
Normally pretty good with mechanics, I've got one that's totally stumped me. My Briggs & Stratton VTwin 22HP will run for about 6-7 minutes, then the governor starts hunting and it eventually dies, even under no load. What's odd is that if you choke it, it'll start right back up (hunting still), then die again. Here's what I've tried already:
At this point I'm at a loss. Not much has turned up on searches so hoping this forum might have some fresh views. Super frustrating because it starts up and mows beautifully... for 6 minutes, at which point it brings out the worst in me.
Any ideas?
- Replaced fuel filter, spark plugs, and air filter, changed oil and oil filter
- Drained fuel and replaced to make sure nothing weird going on there
- Tried running it with air filter off after it's hunting, no difference
- Removed gas cap while hunting, no difference (it's not a vented cap, this design has a hose from the air intake back into the tank for pressure intake - so it's always clean air). Checked hose and it's clear.
- Replaced fuel pump and vacuum hose
- Replaced carb (Nikki carb o-ring seal and jets seem to be a common problem)
- Replaced both magneto armatures (ignition coils), which include attached spark plug wires. Set gap to the specs.
- Checked exhaust while hunting - plenty of air movement coming off
At this point I'm at a loss. Not much has turned up on searches so hoping this forum might have some fresh views. Super frustrating because it starts up and mows beautifully... for 6 minutes, at which point it brings out the worst in me.
Any ideas?
#2
B
bertsmobile1
B
bertsmobile1
This is exactly what happens when you get a build up of clippings in the fuel tank .
While running the debris gets sucked into the outlet then the instant the flow stops it floats away .
The cycle then continues .
If you want to confirm this get a small tank ( pinch one from a push mower ) and hook it up to the inlet side of the fuel pump
While running the debris gets sucked into the outlet then the instant the flow stops it floats away .
The cycle then continues .
If you want to confirm this get a small tank ( pinch one from a push mower ) and hook it up to the inlet side of the fuel pump
#3
W
wesw
W
wesw
I can certainly give that a shot. Given the tank is completely sealed and the vent is through the filtered air I have no idea how anything would have built up. I also did drain the gas tank and nothing came out except gas.
#4
M
MParr
M
MParr
One more thing. Have you drained the carburetor bowl? It’s highly likely that there is a good bit of crud in the bowl.
#5
B
bertsmobile1
In the past there have been recalls because a casting fin would bend over & block off fuel outlets or would catch debris in the tank.
Unless you bought it new in a crate and checked the tank with a mirror before you filled it the first time you can not be sure what was in there.
Over the year I have found all sorts of things inside tanks from condoms to lunch wrappers to price tags , old shop rags, all sorts of stuff.
Then there is the small child factor when some kids had been filling a can with water and tipping it into the fuel tank "just like daddy does "
After an obstruction the next best guess would be a fuel line running too close to the engine / exhaust heating the incoming fuel which causes it to expand & because a carb works on fixed volumes of fuel if the fuel is thinner then less enters the engine so you get a lean burn which makes the engine run hotter which heats the fuel more till the fuel is so hot there is no longer enough to maintain engine function.
B
bertsmobile1
Which is why I suggested the substitute tank to verify the problem.I can certainly give that a shot. Given the tank is completely sealed and the vent is through the filtered air I have no idea how anything would have built up. I also did drain the gas tank and nothing came out except gas.
In the past there have been recalls because a casting fin would bend over & block off fuel outlets or would catch debris in the tank.
Unless you bought it new in a crate and checked the tank with a mirror before you filled it the first time you can not be sure what was in there.
Over the year I have found all sorts of things inside tanks from condoms to lunch wrappers to price tags , old shop rags, all sorts of stuff.
Then there is the small child factor when some kids had been filling a can with water and tipping it into the fuel tank "just like daddy does "
After an obstruction the next best guess would be a fuel line running too close to the engine / exhaust heating the incoming fuel which causes it to expand & because a carb works on fixed volumes of fuel if the fuel is thinner then less enters the engine so you get a lean burn which makes the engine run hotter which heats the fuel more till the fuel is so hot there is no longer enough to maintain engine function.
#6
W
wesw
W
wesw
Brand new carb - bowl is clean.One more thing. Have you drained the carburetor bowl? It’s highly likely that there is a good bit of crud in the bowl.
#7
W
wesw
If that is it I'll have to figure out how to clean it out. It's mounted under a welded frame and I'm mildly concerned that to replace it you'd have to take the engine off.
I haven't replaced the fuel lines themselves. They're routed along a clipped channel on the side - I suppose I could also give that a shot if you think there's anything where swelling, etc... would be heat sensitive. I have blown them out when replacing the filter and fuel pump.
Appreciate the ideas. Will either fix it or rule yet another thing out.
W
wesw
I ordered a small tank to try it out. Be a few days before I can report back on that one, but fortunately at 6 min don't have to wait too long once I get the tank. I can rule out the small children factor though, haven't had those in awhile.Which is why I suggested the substitute tank to verify the problem.
In the past there have been recalls because a casting fin would bend over & block off fuel outlets or would catch debris in the tank.
Unless you bought it new in a crate and checked the tank with a mirror before you filled it the first time you can not be sure what was in there.
Over the year I have found all sorts of things inside tanks from condoms to lunch wrappers to price tags , old shop rags, all sorts of stuff.
Then there is the small child factor when some kids had been filling a can with water and tipping it into the fuel tank "just like daddy does "
If that is it I'll have to figure out how to clean it out. It's mounted under a welded frame and I'm mildly concerned that to replace it you'd have to take the engine off.
After an obstruction the next best guess would be a fuel line running too close to the engine / exhaust heating the incoming fuel which causes it to expand & because a carb works on fixed volumes of fuel if the fuel is thinner then less enters the engine so you get a lean burn which makes the engine run hotter which heats the fuel more till the fuel is so hot there is no longer enough to maintain engine function.
I haven't replaced the fuel lines themselves. They're routed along a clipped channel on the side - I suppose I could also give that a shot if you think there's anything where swelling, etc... would be heat sensitive. I have blown them out when replacing the filter and fuel pump.
Appreciate the ideas. Will either fix it or rule yet another thing out.
#8
M
MParr
How is the air filter?
M
MParr
Is this a genuine Briggs and Stratton carburetor or an Amazon or Fleabay knockoff?Brand new carb - bowl is clean.
How is the air filter?
#9
sgkent
sgkent
sounds like a fuel starvation issue. Try pulling the air filter and cupping your hands closer and closer to the carb inlet as it starts to surge. See if that affects the behavior. If the engine smooths out as you move your cupped hands closer than it is running lean. If it gets worse then it is rich. I had something similar on a pressure washer and a new genuine carb solved the issue. Actually it took two because lots of old stock stuff has been used before. Someone told me that I should also look for cracks in the inlet manifold if it was plastic. Mine was aluminum but a small crack would be easy to over look. Also if one has a loose head it can cause similar behavior. The compression on the pressure washer went from about 30 psi to about 100 psi when I replaced the head gasket and adjusted the valves. Remember that valves grow as the heat up so if they are tight that can be an issue too.
#10
W
wesw
W
wesw
The issue started with the original Nikki carb. It wasn't really excessively dirty but I decided to clean and rebuild it anyway. Also bought a Kohler replacement. Both behave the same way. Pretty sure the carb isn't the problem as the issue exists in both exactly the same. Air filter is also new, forgot to mention that I also replaced that in the original post.Is this a genuine Briggs and Stratton carburetor or an Amazon or Fleabay knockoff?
How is the air filter?
#11
W
wesw
When I had the intake manifold off (mine is plastic) I did check it over carefully for cracks. Didn't see anything, but I didn't have a good way of pressure checking it or anything either.
Haven't checked the head or compression on the valves. If the alternative gas source doesn't fix it, suppose I can check that. The mower only has about 30 hrs on it and it ran fine for probably the first 20 (mower is a few yrs old, so despite lower hrs the warranty is up). When I had the intake manifold there were no signs of a burnt valve or excessive buildup that would change the valve seating. I've never had to adjust valves on one of these B&S VTwin's before - including the 15 yr old John Deere I've got. It looks like a pain from the service manual - remove exhaust, governor, remove and mark push rods just to get to one of the cylinder heads. Gaskets need replaced so rebuild kit. Also appears as if the threads are all using Loctite 242 and torqued 100 ft-lb, so they shouldn't have been creeping to start out with. Is it common in the VTwin's to have some kind of misadjusted valve or head gasket leaks?
W
wesw
Choking it (either via choke or changing carb inlet) will make a minor difference for just a couple seconds but it'll hunt and stall either way. It's hunting so much that it's hard to tell if it's making it better or worse for the short duration.sounds like a fuel starvation issue. Try pulling the air filter and cupping your hands closer and closer to the carb inlet as it starts to surge. See if that affects the behavior. If the engine smooths out as you move your cupped hands closer than it is running lean. If it gets worse then it is rich. I had something similar on a pressure washer and a new genuine carb solved the issue. Actually it took two because lots of old stock stuff has been used before. Someone told me that I should also look for cracks in the inlet manifold if it was plastic. Mine was aluminum but a small crack would be easy to over look. Also if one has a loose head it can cause similar behavior. The compression on the pressure washer went from about 30 psi to about 100 psi when I replaced the head gasket and adjusted the valves. Remember that valves grow as the heat up so if they are tight that can be an issue too.
When I had the intake manifold off (mine is plastic) I did check it over carefully for cracks. Didn't see anything, but I didn't have a good way of pressure checking it or anything either.
Haven't checked the head or compression on the valves. If the alternative gas source doesn't fix it, suppose I can check that. The mower only has about 30 hrs on it and it ran fine for probably the first 20 (mower is a few yrs old, so despite lower hrs the warranty is up). When I had the intake manifold there were no signs of a burnt valve or excessive buildup that would change the valve seating. I've never had to adjust valves on one of these B&S VTwin's before - including the 15 yr old John Deere I've got. It looks like a pain from the service manual - remove exhaust, governor, remove and mark push rods just to get to one of the cylinder heads. Gaskets need replaced so rebuild kit. Also appears as if the threads are all using Loctite 242 and torqued 100 ft-lb, so they shouldn't have been creeping to start out with. Is it common in the VTwin's to have some kind of misadjusted valve or head gasket leaks?
#12
sgkent
sgkent
hold the throttle butterfly steady with your hand and see if the engine speed stabilizes. If so it may be the governor.
#13
D
DaveTN
D
DaveTN
Agree w/ you that it sounds like some sort of fuel starvation even with all that he put on it. I was wondering if the fuel lines themselves might have some internal blockage. Was he using 100% Pure Gasoline? That ethanol will cause hoses to clog up over time as they deteriorate on the inside. But he said he blew out the line. Hmm... still a mystery. Welcome to the LMF!sounds like a fuel starvation issue. Try pulling the air filter and cupping your hands closer and closer to the carb inlet as it starts to surge. See if that affects the behavior. If the engine smooths out as you move your cupped hands closer than it is running lean. If it gets worse then it is rich. I had something similar on a pressure washer and a new genuine carb solved the issue. Actually it took two because lots of old stock stuff has been used before. Someone told me that I should also look for cracks in the inlet manifold if it was plastic. Mine was aluminum but a small crack would be easy to over look. Also if one has a loose head it can cause similar behavior. The compression on the pressure washer went from about 30 psi to about 100 psi when I replaced the head gasket and adjusted the valves. Remember that valves grow as the heat up so if they are tight that can be an issue too.
#14
B
Bertrrr
B
Bertrrr
I've run across this before, bought an electric fuel pump and ran the supply line " new " to a 5 gallon can of gas, crank up and watch it run, no problems , then began replacing fuel lines on the supply side to the tank, ended up finding an air leak on the supply side. make sure your kill selonoid is not the problem as well.
#15
W
wesw
My current plan is to try the new tank like @bertsmobile1 suggested early on. The behavior of this most closely matches his suggestion so far. It's got to either be a blockage that's inconsistent or something heat related. And if it's heat related, it doesn't affect the immediate startup after it stalls. Since the mower as a VTwin should be able to run on only one cylinder and I can see both are getting spark from testers and the spark plugs are new, seems to me unlikely that it's something in the cylinder too as whatever is happening seems to be affecting both cylinders. I also don't think it's the kill solenoid on the bowl as it behaves the same with two different assemblies.
So current plan is 1) check with new small tank, 2) replace fuel lines, 3) check valve/rocker clearance from TDC. Will report back on what if anything helps.
W
wesw
It's a commercial mower, so just using regular unleaded that's supposed to cap out at 10% ethanol; however I did hear that during some of the gas price/shortage issues there was a waiver to allow 15% for awhile... so certainly possible that may have some something. I always use Stabil in whatever I get though. That tank is some sort of metal.Agree w/ you that it sounds like some sort of fuel starvation even with all that he put on it. I was wondering if the fuel lines themselves might have some internal blockage. Was he using 100% Pure Gasoline? That ethanol will cause hoses to clog up over time as they deteriorate on the inside. But he said he blew out the line. Hmm... still a mystery. Welcome to the LMF!
My current plan is to try the new tank like @bertsmobile1 suggested early on. The behavior of this most closely matches his suggestion so far. It's got to either be a blockage that's inconsistent or something heat related. And if it's heat related, it doesn't affect the immediate startup after it stalls. Since the mower as a VTwin should be able to run on only one cylinder and I can see both are getting spark from testers and the spark plugs are new, seems to me unlikely that it's something in the cylinder too as whatever is happening seems to be affecting both cylinders. I also don't think it's the kill solenoid on the bowl as it behaves the same with two different assemblies.
So current plan is 1) check with new small tank, 2) replace fuel lines, 3) check valve/rocker clearance from TDC. Will report back on what if anything helps.
#16
sgkent
have you put a volt meter on the circuit to see if the voltage changes at the time it dies?
sgkent
also don't think it's the kill solenoid on the bowl
have you put a volt meter on the circuit to see if the voltage changes at the time it dies?
#17
W
wesw
W
wesw
Well, I finally got the external tank (it was about 3 days late). Decided to replace the fuel line as well and try it with the new tank. Ran fine for about 20 minutes (had to fill the small tank twice. So I blew out the old tank with an air hose real good, stuck an inspection camera down in it and aside from some vapor it looked really clean. Hooked up the onboard tank and ran it for 30 minutes with no real issues.
So would appear that somewhere between the fuel lines and cleaning out the tank that the problem is solved.
Only other oddity I noticed is that when removing either one of the spark plugs the engine actually seemed to run smoother. Either way though, no stalls this time around. I am wondering though if there is something going on with the diodes and cross talk on the ignition coils. If it happens when warmer outside I might give that a look.
Calling this one solved. Appreciate all the help and ideas from the forum!
So would appear that somewhere between the fuel lines and cleaning out the tank that the problem is solved.
Only other oddity I noticed is that when removing either one of the spark plugs the engine actually seemed to run smoother. Either way though, no stalls this time around. I am wondering though if there is something going on with the diodes and cross talk on the ignition coils. If it happens when warmer outside I might give that a look.
Calling this one solved. Appreciate all the help and ideas from the forum!
#18
W
wesw
W
wesw
So I thought I had this sorted out. But I fired up the mower again today and while it lasted longer (ran about 30 min) it then started to hunt and stall. Video of problem
I've replaced pretty much everything. After it stalls, choke it, will start right back up again. B&S VTwin's 22. Replace
I'm honestly at a loss if anyone has any ideas.
I've replaced pretty much everything. After it stalls, choke it, will start right back up again. B&S VTwin's 22. Replace
I'm honestly at a loss if anyone has any ideas.
#19
M
MParr
M
MParr
Is your governor adjusted correctly? Seeing that video, that would be the first thing that I checked.
#20
T
Tbone0106
T
Tbone0106
Had a similar problem with an older Cub RZT50 that belongs to my church. Replaced all the fuel lines, the fuel filter, the fuel pump, went through the carb, and so on, and it didn't change a thing. Finally pulled off the fender that covers the fuel tank and discovered a brass 90 degree elbow fitting that fits in a rubber grommet on top of the fuel tank. The fuel line feeds from one side of that elbow, but the other side was fitted with a pickup tube made of rigid black plastic, like a big heavy drinking straw. There was no filter on that pickup tube, and the problem lay there. Something -- grass clippings, dead bugs, whatever -- was getting sucked up through that pickup tube from the bottom of the tank, and whatever it was was too large to fit through the brass elbow. The passage through that elbow is MUCH smaller than either the pickup tube or the fuel lines. The elbow was essentially a bottleneck.
The mower would stop at random times, but always start back up after sitting for a few minutes. Whatever was blocking that elbow would drift back down the pickup tube once the engine stopped, and it would be slurped up again sometime later. Lather, rinse, repeat.
What I did to fix things was remove that rigid plastic pickup tube and replace it with a length of standard 1/4" black rubber fuel line. I weighted the bottom end of it with a couple of steel nuts and installed a filter to keep out the inevitable tank-bottom crud.
That was four years ago. That old RZT is still cutting our grass, and it never misses a beat.
Also, FWIW, this fuel pickup design is very much a standard feature on MTD products. I have run into the same problem on other MTD mowers and I've been able to solve the problem in much the same way each time.
The mower would stop at random times, but always start back up after sitting for a few minutes. Whatever was blocking that elbow would drift back down the pickup tube once the engine stopped, and it would be slurped up again sometime later. Lather, rinse, repeat.
What I did to fix things was remove that rigid plastic pickup tube and replace it with a length of standard 1/4" black rubber fuel line. I weighted the bottom end of it with a couple of steel nuts and installed a filter to keep out the inevitable tank-bottom crud.
That was four years ago. That old RZT is still cutting our grass, and it never misses a beat.
Also, FWIW, this fuel pickup design is very much a standard feature on MTD products. I have run into the same problem on other MTD mowers and I've been able to solve the problem in much the same way each time.
#21
W
wesw
Would you be able to take a picture of that when you have a chance? I'm not quite following what you did and how it relates to this design. Thanks!
W
wesw
I know this has a metal 90 degree elbow with a shutoff valve. I cleaned out the tank as thoroughly as possible while troubleshooting everything last time, and also used a small pipe cleaner (the kind kids use in school projects) around that elbow. At this point willing to try about anything.Had a similar problem with an older Cub RZT50 that belongs to my church. Replaced all the fuel lines, the fuel filter, the fuel pump, went through the carb, and so on, and it didn't change a thing. Finally pulled off the fender that covers the fuel tank and discovered a brass 90 degree elbow fitting that fits in a rubber grommet on top of the fuel tank. The fuel line feeds from one side of that elbow, but the other side was fitted with a pickup tube made of rigid black plastic, like a big heavy drinking straw. There was no filter on that pickup tube, and the problem lay there. Something -- grass clippings, dead bugs, whatever -- was getting sucked up through that pickup tube from the bottom of the tank, and whatever it was was too large to fit through the brass elbow. The passage through that elbow is MUCH smaller than either the pickup tube or the fuel lines. The elbow was essentially a bottleneck.
The mower would stop at random times, but always start back up after sitting for a few minutes. Whatever was blocking that elbow would drift back down the pickup tube once the engine stopped, and it would be slurped up again sometime later. Lather, rinse, repeat.
What I did to fix things was remove that rigid plastic pickup tube and replace it with a length of standard 1/4" black rubber fuel line. I weighted the bottom end of it with a couple of steel nuts and installed a filter to keep out the inevitable tank-bottom crud.
That was four years ago. That old RZT is still cutting our grass, and it never misses a beat.
Also, FWIW, this fuel pickup design is very much a standard feature on MTD products. I have run into the same problem on other MTD mowers and I've been able to solve the problem in much the same way each time.
Would you be able to take a picture of that when you have a chance? I'm not quite following what you did and how it relates to this design. Thanks!
#22
W
wesw
W
wesw
Not much to adjust; however given it runs fine for about 30 minutes and warmup should happen well before that, I think something else is going on. Adjustment in the manual just talks about bending the arm a little one way or the other if necessary.Is your governor adjusted correctly? Seeing that video, that would be the first thing that I checked.
#24
L
leemalis
L
leemalis
Did you ever fix the problem? I have a motor doing the exact same thing? I've replaced the carb, filter, fuel lines, thermostat (choke thing). I will try the second fuel tank idea.
#25
W
wesw
W
wesw
I have not gotten it fixed yet. I just set the governor... although per the video above it was already tightened and I don't expect any change. I also searched around for common vacuum leaks and replaced the two gaskets at the intake manifold to engine. When I removed them originally they looked somewhat bent like in a picture. I flipped them around backwards but decided to just replace. At the moment it's failing to even crank, so I have to do a little more troubleshooting to see why the starter/solenoid isn't running before I can even test it out. I might have gotten a lemon... but seems like there is ALWAYS something wrong with this thing.
I was hoping to get some pictures around what the other guy did on the 90 degree fuel line. I've already emptied, blown out the tank, and replaced the gas lines... but it would be interesting if there was something more up in there. I did get a little motorcycle gas tank and run it that way for awhile to test. It drains the smaller one in just a couple min, so for it to run for awhile I think my on-machine gas tank is alright. I know there is nothing down in there as I've blown it out and checked with an inspection camera.
I was hoping to get some pictures around what the other guy did on the 90 degree fuel line. I've already emptied, blown out the tank, and replaced the gas lines... but it would be interesting if there was something more up in there. I did get a little motorcycle gas tank and run it that way for awhile to test. It drains the smaller one in just a couple min, so for it to run for awhile I think my on-machine gas tank is alright. I know there is nothing down in there as I've blown it out and checked with an inspection camera.
#26
sgkent
sgkent
this came to me based on something similar someone had happen here some time ago. Don't over tighten the gas cap. Someone had a model where over tightening it caused the cap vent not to work.
#27
W
wesw
W
wesw
It's a good callout, but this one doesn't have a vent cap. It's a commercial model that has a separate vent tube which is ultimately connected through the air filter - so it only pulls in clean air.this came to me based on something similar someone had happen here some time ago. Don't over tighten the gas cap. Someone had a model where over tightening it caused the cap vent not to work.
#28
W
wesw
W
wesw
I adjusted the governor (though I think it was already tightened as much as it would go per the video) and I also replaced the intake seals on the manifold (someone mentioned that was a common source of vacuum leak). Neither really made any difference unfortunately. It ran for ~25 min and then stalled and started with the hunting. I may replace the VTwin valve cover gaskets, just because they're cheap and since the fuel pump is being pulled by the right side I figure it's worth making sure that isn't a vacuum leak... although when I do the propane test/trick nothing seems to stop the hunting.
Any other ideas? @leemalis - did the alternate fuel tank test do anything on yours?
Any other ideas? @leemalis - did the alternate fuel tank test do anything on yours?
#29
sgkent
sgkent
make sure it is clean and open. The description of the problem is classic for a plugged tank vent.It's a good callout, but this one doesn't have a vent cap. It's a commercial model that has a separate vent tube which is ultimately connected through the air filter - so it only pulls in clean air.
#30
W
wesw
W
wesw
I'm positive it's not the plugged tank. The rather large air line is clean ... and even when you take the gas cap off it doesn't make any difference in how it runs. An external tank doesn't seem to fix the problem either.
I need to run it some more to be sure, but I replaced the valve cover gasket where the fuel vacuum line is attached yesterday. I thought it was just dirty but when I got in there I realized it was oily dirt and the other side had none of that. The silicone seal from the factory wasn't great ... but clearly there was some oil coming out. I'm not 100% sure yet it solved this problem yet either, but I think it might have been heating up and creating enough of a vacuum leak there to have some fuel starvation.
I need to run it some more to be sure, but I replaced the valve cover gasket where the fuel vacuum line is attached yesterday. I thought it was just dirty but when I got in there I realized it was oily dirt and the other side had none of that. The silicone seal from the factory wasn't great ... but clearly there was some oil coming out. I'm not 100% sure yet it solved this problem yet either, but I think it might have been heating up and creating enough of a vacuum leak there to have some fuel starvation.
#31
T
Tbone0106
The 90-degree elbow I'm talking about is plain brass, without a shutoff valve. It is mounted in a rubber grommet in the top of the plastic fuel tank. Because its inside diameter is considerably smaller than either the pickup tube or the fuel line, it is a fairly obvious choke point in the fuel system. And since the factory pickup tube is unfiltered, I removed it and replaced it with a length of standard fuel hose with a filter on the bottom end, weighted with a couple of old steel nuts. There are pickup filters made for some older Stihl chainsaws that fit standard 1/4" fuel hose perfectly.
T
Tbone0106
I'm not sure what you want a picture of. What I did to fix the problem is all inside the fuel tank, and it would be pretty tricky for me to get pictures of that.I know this has a metal 90 degree elbow with a shutoff valve. I cleaned out the tank as thoroughly as possible while troubleshooting everything last time, and also used a small pipe cleaner (the kind kids use in school projects) around that elbow. At this point willing to try about anything.
Would you be able to take a picture of that when you have a chance? I'm not quite following what you did and how it relates to this design. Thanks!
The 90-degree elbow I'm talking about is plain brass, without a shutoff valve. It is mounted in a rubber grommet in the top of the plastic fuel tank. Because its inside diameter is considerably smaller than either the pickup tube or the fuel line, it is a fairly obvious choke point in the fuel system. And since the factory pickup tube is unfiltered, I removed it and replaced it with a length of standard fuel hose with a filter on the bottom end, weighted with a couple of old steel nuts. There are pickup filters made for some older Stihl chainsaws that fit standard 1/4" fuel hose perfectly.
#32
B
BWC4WIFE
B
BWC4WIFE
Gas Cap
Same issue — well similar. My new (Chinese) carb musta had some debris in the main jet. I soaked it for 20min in CarbCleaner and blew it out — fixed one issue.
But running for a bit and then dying that’s the gas tank creating a vacuum bc it’s not venting. When it starts to slow down unscrew the cap a little and it’ll pick back up. But you can only cheat it for so long
Same issue — well similar. My new (Chinese) carb musta had some debris in the main jet. I soaked it for 20min in CarbCleaner and blew it out — fixed one issue.
But running for a bit and then dying that’s the gas tank creating a vacuum bc it’s not venting. When it starts to slow down unscrew the cap a little and it’ll pick back up. But you can only cheat it for so long
#33
W
wesw
W
wesw
Mine wasn't gas cap - as mentioned it's not a vented cap design, pulls air through a hose that's filtered from air filter.
I think I have finally fixed the issue. @bertsmobile1 had suggested it was fuel related early on. I ended up replacing the screw in shut-off valve and the problems largely went away. I couldn't find anything in particular wrong with the old one when I tore it apart, but I did notice the new one had an integrated filter, and of course the rubber washers were in much better shape. It's a pretty poor design that's being used in the valves, the fuel takes so many right turns it's amazing it makes it anywhere sometimes.
I think I have finally fixed the issue. @bertsmobile1 had suggested it was fuel related early on. I ended up replacing the screw in shut-off valve and the problems largely went away. I couldn't find anything in particular wrong with the old one when I tore it apart, but I did notice the new one had an integrated filter, and of course the rubber washers were in much better shape. It's a pretty poor design that's being used in the valves, the fuel takes so many right turns it's amazing it makes it anywhere sometimes.