Most things come down to money. Yes it makes sense to create more efficient/lower emissions equipment as time goes on. Fixing the old gear and not having to scrap it and manufacture the replacement machine is probably a lot better for the environment even if the old machine creates more emissions. But that doesn't help the economy at all does it?
Cold start issues 1981 Briggs 11hp model 25
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Yesterday I shut off the fuel and let it completely run out (took like 60 seconds at least idling before it finally died - maybe the shutoff isn't sealing perfectly?) This morning I turned on the fuel and immediately tried to start it ..still the same thing, fires briefly and stalls...over and over again firing a little bit longer each time before dying. No real noticeable smoke or smell despite being in my garage. I ordered a new Chinese carb from the states so I guess that's my next attempt to fix it. I've been driving carbureted cars for 22 years since I was 16 and this behaviour seems odd to me, but obviously a single cylinder Briggs with manual choke is not the same as a V8 with a 4 barrel with electric choke.
I accidentally stopped the video I was recording at 1 second...so I'll just post the one from yesterday. The issue is much worse the longer it sits...after the first few failed starts ...it seems to prefer around 3/4 throttle but it will start at any throttle position except choke once it's get a tiny bit of heat into it. My original thought was not enough choke closing but that doesn't seem to be the case.
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artemjemmy
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You have no way of knowing that the fuel shut off is actually working anymore. I just changed an in-line fuel shutoff that was leaking last week. Sure, mine was plastic and yours is metal, but it is still definitely possible that it is leaking, especially being almost 40 years old.
How long do you estimate it should take to empty the float bowl? It eventually shuts off and will not restart but it could be leaking a small amount.
artemjemmy
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So in the video the main thing I am noticing is just how slow it is running once it does start popping, and then dies. Once these engines start running, within about a second they should immediately be running up at full throttle speed. It almost seems like the throttle plate isn't open all the way. This is why I believed it had bad compression to begin with, but your 150 psi reading shows otherwise. Can you please drain the float bowl, then leave it for a while and try to cold start it with just starting fluid, to see if it does exactly the same thing? This will eliminate the possibility of any carburetor problems and narrow this down.Yesterday I shut off the fuel and let it completely run out (took like 60 seconds at least idling before it finally died - maybe the shutoff isn't sealing perfectly?) This morning I turned on the fuel and immediately tried to start it ..still the same thing, fires briefly and stalls...over and over again firing a little bit longer each time before dying. No real noticeable smoke or smell despite being in my garage. I ordered a new Chinese carb from the states so I guess that's my next attempt to fix it. I've been driving carbureted cars for 22 years since I was 16 and this behaviour seems odd to me, but obviously a single cylinder Briggs with manual choke is not the same as a V8 with a 4 barrel with electric choke.
I accidentally stopped the video I was recording at 1 second...so I'll just post the one from yesterday. The issue is much worse the longer it sits...after the first few failed starts ...it seems to prefer around 3/4 throttle but it will start at any throttle position except choke once it's get a tiny bit of heat into it. My original thought was not enough choke closing but that doesn't seem to be the case.
artemjemmy
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Really difficult to say, since basically all carburetors have minute differences that will have big changes in AFR over different fuel level bowl heights. I would say anywhere from 45 seconds to 3 minutes you should start to notice lean running symptoms as fuel level drops. To really be sure, can you disconnect the fuel line all together?
Will do that next. The weird thing is after multiple attempts it eventually comes to life like a switch turned on and it revs up quickly. Then it has plenty of power for mowing and towing once it's warmed up a minute or two.
artemjemmy
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Also, I will be honest in that I highly doubt 150 psi is possible on these engines, so I somewhat doubt that compression reading you showed. Nothing personal, but that number just seems significantly too high.
The cylinder would still have had some of the oil and transmission fluid I squirted in....so it would have been probably somewhat inflated by that. But I'm thinking that would typically only make a difference of like 10-20 psi usually.
bertsmobile1
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Cylinder compression in PSI is roughly 14 ( atmospheric pressure ) x the compression ratio
So 150 / 14 = 10.7:1
very few mowers run better than 9:1 unless they are EFO engines and computer controlled .
Most are in the 7:1 to 9:1 for OHV and 6:1 to 7:1 for side bangers
Some of the older ones are as low 5:1
So 150 PSI does sound more like an error than an accurate reading
So 150 / 14 = 10.7:1
very few mowers run better than 9:1 unless they are EFO engines and computer controlled .
Most are in the 7:1 to 9:1 for OHV and 6:1 to 7:1 for side bangers
Some of the older ones are as low 5:1
So 150 PSI does sound more like an error than an accurate reading