i have a good one, on a 1984 h34 i get a engine vibration alittle higher than idle when hot, trying to re-speed up to 2000rpm. when cool, for the first 20 minutes, you can run the yanmar 3gm30f at any speed you want, up or down the power band with compleate smoothness, but when it gets really warm, and you throttle back below 2000rpm it shakes real bad as as though its misfiring . the remedy is to punch the throttle back up to around 3000rpm ,and it smooths out again for the whole afternoon, as long as you dont drop below 2000. i replaced the whole package from the coupling to the 15x12 prop, a new exhaust elbow, and all new injectors. it starts all the time with less than 1 rev, and can run up to 3500 without smoke. whats going on?
ENGINE MISFIRING
- Thread starter VINN
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My guess is ,,,
a problem with the injector pump. Since all injectors are new the probability is the pump. However, after 10 yrs. as a diesel mechanic, I have learned that it isn't impossible that one of the new injectors is malfunctiong. Try this - run the engine at a low rpm and while it is missing, crack and bleed each injector to locate the cylinder in question.(The culprit won't change a thing the engine is doing.) Switch that injector with another and see if the problem moves. If not, the problem is specific to that cylinder. A sticking valve is one possibility in addition to the injector pump.
a problem with the injector pump. Since all injectors are new the probability is the pump. However, after 10 yrs. as a diesel mechanic, I have learned that it isn't impossible that one of the new injectors is malfunctiong. Try this - run the engine at a low rpm and while it is missing, crack and bleed each injector to locate the cylinder in question.(The culprit won't change a thing the engine is doing.) Switch that injector with another and see if the problem moves. If not, the problem is specific to that cylinder. A sticking valve is one possibility in addition to the injector pump.
nothing to do with fuel problems!
well we finally figured it out after two seasons under our belt, the help of one h34 owner on the forum, joeO from over a year ago,helped us solve it. we read over 3hrs, of gossip on the hunter site ,and only he had the clue we were looking for. when we read his article, we remembered it does not shake in reverse. that meant it was'nt a fuel problem like so many experts suggested. nor was it a drive line problem, i remembered one quote, if it does'nt do in in idle, it was definitely a shaft alignment problem. i really felt bad for the guy that tried 4 shafts! we just went through 1. it turned out to be just a linkage adjustment to the trainy, allowing the shifter to slip in and out of gear. it sounded like a misfire, or poor timing, but was just some play in the engagement. i hope my article helps other weekend mechanics in the future, go through allot less agony, and money!
well we finally figured it out after two seasons under our belt, the help of one h34 owner on the forum, joeO from over a year ago,helped us solve it. we read over 3hrs, of gossip on the hunter site ,and only he had the clue we were looking for. when we read his article, we remembered it does not shake in reverse. that meant it was'nt a fuel problem like so many experts suggested. nor was it a drive line problem, i remembered one quote, if it does'nt do in in idle, it was definitely a shaft alignment problem. i really felt bad for the guy that tried 4 shafts! we just went through 1. it turned out to be just a linkage adjustment to the trainy, allowing the shifter to slip in and out of gear. it sounded like a misfire, or poor timing, but was just some play in the engagement. i hope my article helps other weekend mechanics in the future, go through allot less agony, and money!
Thanks for the update VIN.
Lots of gear-heads like me were hanging out on this thread. A real head-scratcher.
Lots of gear-heads like me were hanging out on this thread. A real head-scratcher.
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