"Ron.... Regardless of the pro
"Ron.... Regardless of the problem, it is wise to always check the compression and spark first. Did you?
Compression should be in the range of 100 psi and even on all cylinders. Spark, with the plugs out, should jump a 7/16" gap with a strong blue flame on all cylinders.
If the above checks are okay, I would suspect that you have fouled carburetors which would result in having the engine run lean. The cure would be to remove, clean, and rebuild them.
Also, the timer base under the flyuwheel might be sticking, not hitting the full spark advance stop, which would result in having the engine run at a retarded spark setting.
If that timer base is sticking (or even if it isn't), check the stator assy under the flywheel to see if it may be leaking any substance out of it. That stator is the beginning of the charging and the ignition syatem. If either of the larger (black)coils within the stator start to melt sown, voltage being applied to the powerpack drops which results in erratic ignition.
Spark plugs should be Champion QL77JC4 plugs, with the gap set to .040 .
If a anti siphon valve were at fault, the engine would perform properly at first, then as it is being run a fuel restriction would take place, effectively causing the engine to run lean. From what you've said, the engine does not run properly even at the beginning so this, apparently, is not the case with your engine.
However, I will list the info pertaining to a anti siphon valve so that it may be understood as follows:
(Fuel Anti Siphon Valve)
Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vaccum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.
NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.
The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it.
Joe
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