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Evinrude Backfired now wonbt start at allHELP

T

thomjw

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" Help Joe,
yesterday my 1985

" Help Joe,
yesterday my 1985 evinrude 235 v-6 vro stalled and then backfired when I tried to re-start. Now all it will do is backfire (thru exhaust not carb)when I try to start it. I cleaned the plugs (nearly new)emptied out the gas and re-filled, cleaned out the gas filter. (even tried starting fluid) I have spark at all the plugs. The compression is exactly the same on all cylinders. It is acting like a car that has jumped timing. I know a 2-stroke can't do that, but that is the symptom. I checked the timing with all the plugs out and cranked it. It read TDC. I manually held open the advance thing against the stop and cranked it and it read 20 degrees. I'm stumped! This was the first time I had it out this year. It ran fine for about 30 minutes, and while trying to pull it toward shore to trailer it, it stalled and now nothing will get it to start. Is it possible that the electronic ignition is bad even though the spark is there? "
 
"Thom..... I suspect that one

"Thom..... I suspect that one of two things have taken place.

1 - If the flywheel has been removed at one time, the flywheel nut was not torqued correctly. It must be torqued to exactly 105 foot pounds.

If not torqued correctly, eventually the flywheel key will shear, allowing the flywheel to slip slightly past its proper location on the crankshaft. That condition throws the engine out of time! You will still have ignition (spark) but at the wrong time.

2 - The engine has two (2) powerpacks. Each one has a diode which prevents it from interfering with each other. If a diode fails for any reason, the pack with the faulty diode will cause the opposite pack to double fire ie a cylinder on the port and starboard bank will fire at the same time.

I suspect the flywheel scenario myself, and if so, you will need to clean the crankshaft and flywheel tapers thoroughly.

Joe
"
 
" Thanks Joe, I will remove th

" Thanks Joe, I will remove the flywheel and check it first. I just bought a selog manual, I will look in it to see if there is a test to check the diode that you described. I bought the boat used last year, and the guy hadn't had it long himself, so I wouldn't be surprised if the flywheel had been off before. Thanks again! By the way, do you still work on these? I might need to take it somewhere. I am in New Jersey (south). "
 
"Thom.... You said "By the

"Thom.... You said "By the way, do you still work on these? I might need to take it somewhere. I am in New Jersey (south)."

I do a little work from time to time but not eight hours or so a day any more. I lived in So Jersey (Millville) for many years, starting this trade at Henderson Boat Yard in Port Elizabeth around 1960, then moved up to the Sport Spot in Vineland for awhile. Left Jersey in 1977, continuing in the trade in Central West Florida.

Joe
"
 
" THANKS JOE !!!!!! it was the

" THANKS JOE !!!!!! it was the keyway, sheared. and the magnets were loose and moving. i re-epoxied them, new keyway, torqued properly, and it works great. thanks again
thomjw "
 
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