Problem: 2001 Craftsman tractor with 25 HP Twin ELS engine runs fine most of the time. However, if I am doing a lot of work with the tractor pointing uphill (like dragging the driveway-300 ft mild uphill grade) the engine will start to miss and may cut out before I get to the top. Or, if I am mowing and I stay pointing uphill too long, it will miss. If I get pointed down hill quickly, the engine will recover. Engine starts and runs great on level ground. Engine RPMs increase when I engage the mower.
I have done/replaced the following:
New carb
New fuel pump
New fuel filter
New Air filter
New plugs
All new fuel lines
New pulse line for fuel pump
Removed and cleaned fuel tank
New valve cover gaskets
Used fresh gas
Adjusted valves to .004
Checked gas cap vent and tried running with cap loose
Changed oil and filter
Removed cooling shroud and thoroughly cleaned engine exterior
Used compressed air in fuel line from filter to tank
What is causing this uphill only condition??? I am out of ideas.
Thanks in advance
#2
Fish
Just for testing purposes, take it out again, and head uphill, and when it starts to miss slowly pull out the choke know while still moving and see if the running improves or what.
Sometimes I can nurse it by modulating the choke, say 1/4 choke, but after 30 secs or so it will start to miss at that setting. Only real cure it to get it to level ground for a spell.
This tractor has been used year round since I bought new in 2001, probably well over 200 hours a year. On some weekends, I may run it for 5 or 6 hours almost constantly (small breaks). So it most likely has over 2500 hours.
I am running straight 30 weight oil and the new oil filter is a genuine B&S filter.
Just came in from mowing the front yard and made the following observations.....
Engine was cold to touch when I started. Ran fine for first 15 minutes in all orientations, then it started in with the uphill issues. I could nurse it with choke to a level area and idle for a minute then was good to go for a few rounds. Eventually I couldn't nurse it and it died completely. I pulled the hood and the carb was too hot to touch. Let it sit for 5 minutes and it restarted fine, no choke.
At this point I am thinking excessive heat and, duh, it is probably my fault.
Last year, one of the "wings" on the heat shield/dissipater for the muffler/exhaust broke off. I removed the shield with the intention of getting it welded. Well, as we all know, one thing leads to another and this got put of to the point of where I lost the wing, so I intended to order a replacement next time I ordered parts. As of right now, the shield is still off the tractor.
So, my question is...
Do you think that a carb could overheat enough to the point where the float would not move freely enough in some directions? I have never torn down this type of carb so I am not familiar with the swing direction of the float. As soon as things cool off enough I going to re-install what I have of the heat shield. The mounting bolts also retain the muffler so they are very hot.
After I install the shield, I still have enough work to do to give it a good test.
Fish,
I really appreciate the attention and suggestions you have provided.
#9
Fish
Well the added info might mean a lot. Remove the hood and leave it off. Also, just for test purposes, take some aluminum foil and make a baffle to lay over the exhaust, and lock it down as best you can, then test.
#10
Fish
the extra heat, and upward angle, with that heat collecting from the missing part, may allow a bunch of heat to collect up around the carb, and eventually make the fuel boil, or it may put extra heat on the valves and make them expand more, but this may be what you were lookin for. Leave the hood off for starters, but try and channel that heat away too.
I re-installed the shield and she ran for almost twice as long as before before having problems. I guess I'll put in an order for a new shield and see what happens when I have a complete piece on.
The wing on the side of the shield is roughly 25 square inches in size or about 25% of the total size. Also, the wing that is still attached is barely hanging on (if I flex it once it will probably break off) and felt barely warm when I touched it so it is not doing its job to dissipate any heat.
The heat shield id number 10 in the linked diagram.
wing on the side of the shield is roughly 25 square inches in size or about 25% of the total size. Also, the wing that is still attached is barely hanging on (if I flex it once it will probably break off) and felt barely warm when I touched it so it is not doing its job to dissipate any heat..
The shield is steel. The barely warm temp was lot less than the main part of the shield. The wing was about 3-4 seconds on a touch test, where as the main part was 1 second on a touch test. The existing wing is only hanging on by about a 1/4 of un-cracked metal.
I may have some foil backed insulation in the basement to try shielding the carb. Will have to wait until tomorrow for that.
Once again I want to say thanks for the assistance.
Sometimes it helps a lot to bounce problems off of a knowledgeable person. Everyone at work and the neighbors are all non-mechanical in nature and usually ask me for help or take it to a shop. When you get the chance to lay it out to someone else who understands, you tend to start looking at every little detail. Wish I had thought of the heat shield earlier.
I think I should also order replacement springs for the govenor while I am ordering parts. If they overheated too much, too often, their temper may have changed.
#14
Fish
Nah..... The springs should not even be considered here...
as far as the rest of it, something unique has to being happening, so one must know/hear of the whole story...
But my gut tells me that you have some pesky moisture in your system, but on a discussion forum, every possibility is always nixed by the original poster, and all of the gang here always takes the side of the original poster.....
Nothing personal, but we get a lot of "head scratchers" which usually means some missed detail....
Nothing personal taken:smile: I understand that free help and advice should always be taken with an air of gratitude and it is a 2 way street so all of my replies will be of the most professional nature.
At this point I am willing to try anything, so I will pick up some dry-gas next time in town and add it to the tank. Maybe even my "fresh" gas is not that great, so I'll grab another 5 from a different station.
I will also try insulating the carb/intake until the new shield comes in. I have an infrared thermometer I can shoot at things so I'll keep it with me next time I am using the tractor and take a reading on everything when it screws up.
As far as details go, I am trying my best to provide every possible thing that may be a contributor and everything that I have tried. Sometimes you just don't think of everything until someone else bounces an idea off your noggin.
This problem reminds me of one I had with a 1984 Camaro (V-8, 4 barrel carb). On extremely long trips of 100 miles or more non-stop, it would start acting like it had vapor lock. Multiple trips to the dealer and they either couldn't replicate (never ran it long/hard enough) or they would throw parts at it (new carb, new filter, new distributor module, insulated fuel lines). Finally onetime, on my way home from the beach the fuel pump went out, started leaking gas out the vent (manual pump, cam driven, hanging on front side of block). So I slapped a new fuel pump on and never had the problem again. Best guess is that a very small puncture existed on the diaphragm and when the fuel pump housing expanded from prolonged heat exposure, that puncture also enlarged when the diaphragm stretched resulting in loss of fuel pressure.
#16
Fish
Yes, it indicates some water in the fuel, it can be real pesky, as it will sit in a small layer in the bottom of the carb bowl, and will just stay there and corrode things.
Then occasionally some will get slurped into the engine when turning, hitting a bump, or going up-downhill. I liked the old fashioned fuel separator-filters, where you
had a glass bowl that would collect the water, that could be easily seen and discarded.
After cleaning out the gas tank again and fully cleaning the carb, along with the new heat shield, she seems to be running without issue and I haven't had her cut out on me. I still have a new breather to put on and have a few questions on that.
I read the manual and it says to remove the flywheel to replace the breather, and that requires special tools. So, is it possible to replace the breather with the flywheel in place? Looks like if I remove the intake I can get to the bolts, but don't know if there is enough vertical clearance to remove the bolts and breather.
Any advice on breather replacement on the vertical v-twin?
This probably doesn't mean anything but what I'm thinking is the float in the carb is meant to function on level or almost level ground. With the mower going uphill or downhill the float's movement is hampered by the incline. As you say the engine straightens out when you are level. You'd think that with all the vibration the carb would still function but with the float hung up [to the side] the needle may be closed or drastically stay open - regulating, really, NOTHING.
