Joe Reeves
Supreme Mariner
- Joined
- Feb 24, 2002
- Messages
- 13,262
Re: 1989 Evinrude V6 Engine Trouble
As Dhadley has stated, if the engine is indeed a crossflow engine, the dual throat carburetors are designed so that one side of the carburetor can have a negative effect on one bank without affecting the other bank.<br /><br />The confusion seems to be that possibly the carburetors weren't cleaned properly as it was stated that the engine ran worse AFTER the carburetors were cleaned. If the carburetors have both fixed IDLE and INTERMEDIATE jets, then those jets could have been installed in the wrong location as many of those two function jets are of the same physical shape and thread size.<br /><br />Most engines, when they've sat up for a period of time, especially the crossflow engines, are in a tilted position and turned to one side. This usually causes the high speed jets on one side of the carburetors to clog more so than the other side. If the high speed jets were not removed and cleaned manually, it's possible that the center and lower carburetor have clogged high speed jets pertaining to the starboard bank (#3 & #5).<br /><br />I'm assuming that the carburetors have been installed in their proper location and that the linkages are correct.... and that this is indeed a crossflow engine as stated.<br /><br />What is the model number of that engine?<br /><br />The compression has only 5lbs difference between the lowest and highest reading... that's fine, and the average reading of the 1989 V/6 engines is usually around 90 psi.<br /><br />Remove the spark plugs, rig a spark tester so that you can set a gap of 7/16". At cranking speed, the spark should jump that gap with a strong blue lightning like flame. If not, find out why and let us know about it.<br /><br />The proper s/plug would be Champion QL77JC4 plugs, gapped at .040 .<br /><br />If the compression and spark are as they should be, that leaves a fuel condition. The reason (my line of thought) that the cylinder kicks in momentarily when you put the plug wire back on would be that the lean carburetor(s) were supplying fuel to that cylinder, building up in volume (fuel) enough to have a response when the plug wire was reattached.<br /><br />To rule out a erratic coil, simply switch coils.<br /><br />To check for a lean running, fouled carburetor, have the carburetor face plate off with the engine running at a idle. One carburetor throat at a time, insert two fingers into its throat. If the rpms increase, that portion of that carburetor has a clogged jet, passageway, a restriction of some kind.
As Dhadley has stated, if the engine is indeed a crossflow engine, the dual throat carburetors are designed so that one side of the carburetor can have a negative effect on one bank without affecting the other bank.<br /><br />The confusion seems to be that possibly the carburetors weren't cleaned properly as it was stated that the engine ran worse AFTER the carburetors were cleaned. If the carburetors have both fixed IDLE and INTERMEDIATE jets, then those jets could have been installed in the wrong location as many of those two function jets are of the same physical shape and thread size.<br /><br />Most engines, when they've sat up for a period of time, especially the crossflow engines, are in a tilted position and turned to one side. This usually causes the high speed jets on one side of the carburetors to clog more so than the other side. If the high speed jets were not removed and cleaned manually, it's possible that the center and lower carburetor have clogged high speed jets pertaining to the starboard bank (#3 & #5).<br /><br />I'm assuming that the carburetors have been installed in their proper location and that the linkages are correct.... and that this is indeed a crossflow engine as stated.<br /><br />What is the model number of that engine?<br /><br />The compression has only 5lbs difference between the lowest and highest reading... that's fine, and the average reading of the 1989 V/6 engines is usually around 90 psi.<br /><br />Remove the spark plugs, rig a spark tester so that you can set a gap of 7/16". At cranking speed, the spark should jump that gap with a strong blue lightning like flame. If not, find out why and let us know about it.<br /><br />The proper s/plug would be Champion QL77JC4 plugs, gapped at .040 .<br /><br />If the compression and spark are as they should be, that leaves a fuel condition. The reason (my line of thought) that the cylinder kicks in momentarily when you put the plug wire back on would be that the lean carburetor(s) were supplying fuel to that cylinder, building up in volume (fuel) enough to have a response when the plug wire was reattached.<br /><br />To rule out a erratic coil, simply switch coils.<br /><br />To check for a lean running, fouled carburetor, have the carburetor face plate off with the engine running at a idle. One carburetor throat at a time, insert two fingers into its throat. If the rpms increase, that portion of that carburetor has a clogged jet, passageway, a restriction of some kind.
