Okay, I posted a little about this in a carburetor thread, but I'm not so sure it's the carb, anyway here is the problem. After driving at a constant speed for a few minutes in 4th gear, the truck will buck and misfire, if I lay off the throttle it seams to correct itself, but will do it again after a few minutes. I will say the the fuel tank is pretty low, is it possible I'm sucking crap up from bottom of tank or water in tank causing something like this? The sediment bowl is clean, but there is an in-line filter after that that I plan on replacing.
For the record I have a late 2.25L, probably a 5 bearing. It has a 32/34 Weber DTML two-barrel carb on it which I'm told is what the 2.5 liter engine came with. I'm guessing this engine has no internal mods to make use of the bigger carb. I'd like to convert back to a single barrel, but I'm afraid that there will be a snowball effect of pieces to replace. Hoping to hold off on this until I rebuild the whole truck if possible.
Here's what I've done:
1)Full tune-up; plugs, cap, rotor, points, condenser, coil, wires, plugs. Double and triple checked gaps for points and plugs. This was done prior to this problem and made a world of difference at that point
2) ran 2/3 of a bottle of Sea Foam through the carb, lots of blue smoke, and the engine actually seems to run a little smoother. It had a valve tap that has quited down quite a bit after this. Problem seems a little less severe after this as well, recovers quicker.
3) adjusted valve tappet clearance (did this during tune-up prior to this problem)
4) Timing is set to about +5 degrees, which should be consistent with running 87 octane
5) replaced sediment bowl and screen on fuel pump
Things left to do:
1) replace in-line fuel filter
2) compression test and general spark plug check (checked the #1 plug and it looked great)
3) double-check timing
4) Mostl likely replace carb since it is a model that does not seem to be available in the U.S.
That's about all of the info I have for now, I'll report back with compression test results. Feel free to chime in if you have any ideas. The engine runs perfectly smooth, has lots of power (relatively speaking) and drives great, until it bucks all of a sudded and misfires.
For the record I have a late 2.25L, probably a 5 bearing. It has a 32/34 Weber DTML two-barrel carb on it which I'm told is what the 2.5 liter engine came with. I'm guessing this engine has no internal mods to make use of the bigger carb. I'd like to convert back to a single barrel, but I'm afraid that there will be a snowball effect of pieces to replace. Hoping to hold off on this until I rebuild the whole truck if possible.
Here's what I've done:
1)Full tune-up; plugs, cap, rotor, points, condenser, coil, wires, plugs. Double and triple checked gaps for points and plugs. This was done prior to this problem and made a world of difference at that point
2) ran 2/3 of a bottle of Sea Foam through the carb, lots of blue smoke, and the engine actually seems to run a little smoother. It had a valve tap that has quited down quite a bit after this. Problem seems a little less severe after this as well, recovers quicker.
3) adjusted valve tappet clearance (did this during tune-up prior to this problem)
4) Timing is set to about +5 degrees, which should be consistent with running 87 octane
5) replaced sediment bowl and screen on fuel pump
Things left to do:
1) replace in-line fuel filter
2) compression test and general spark plug check (checked the #1 plug and it looked great)
3) double-check timing
4) Mostl likely replace carb since it is a model that does not seem to be available in the U.S.
That's about all of the info I have for now, I'll report back with compression test results. Feel free to chime in if you have any ideas. The engine runs perfectly smooth, has lots of power (relatively speaking) and drives great, until it bucks all of a sudded and misfires.