Sputtering G705 LP

toolz

Well-known Member
I'm having some problems with my G705 LP. Plowed with this tractor two years ago with no issues, been using it at tractor pulls since. Last weekend I went to a plow day
with it, and as soon as it got good and warmed up, maybe 1/4 mile with the plow, it started backfiring and missing. As soon as it idles for a bit, it pulls fine again.
Figured it was an ignition problem, so I replaced the points system with a new GM HEI setup that I've had around, along with new wires. Went to another plow day today,
and had the exact same problem. Took out the plugs and gaped them to .050 for the HEI, but no change. I haven't replaced the plugs, but I would be surprised if that's the
problem. They look fine. It seems to me that if it's a fuel problem, it would just lose power, not backfire. I'm thinking I may have a thin valve edge that's getting hot
enough to cause pre-ignition, or possibly a valve or two sticking when it gets warm. Anybody familiar with this problem, or have any suggestions?
 
As stated in my post, I replaced the entire ignition system with a new HEI and wires, with no change.
 
I agree with your reasoning on possible fuel problem but you might check the little filter. Not much to it, cotton I think. Have seen those get really nasty with crud and dead bugs, spider webs, rust, etc. Easy and quick check. Just a suggestion...have seen it give guys fits.
 
I appreciate the suggestion. I did replace the filter a couple of years ago. It was in bad shape.
 
Hello tools,

Two things change when you idle the engine. One, less fuel is needed. Two, the spark plugs cool off. One other possibility would be a valve getting tight under load. Exhaust or intake? Listen where it's coming from. Lean mix will pop in the intake side,

Guido.
 

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