Runs on muffs, dies in water

[garyinva]

'75 Evinrude, 70 HP, It starts and runs in the backyard on muffs, even in gear,and at higher speeds. But when I put it in the water it idles rough and dies when I put it in gear. Spark looks good, new fuel pump, new fuel lines. Have not pulled off carbs yet, thought I'd get some opinions first. Do you think it would be a fuel or ignition problem?? Where should I start? Should bulb stay firm continuosly, cause it doesn't. thanks for any suggestions.

 

[Steve135]

Re: Runs on muffs, dies in water

Well it dies due to the back pressure from being in the water and water pressure being at the exhaust! This is due to a number of reasons. Due a search on this web site for the same type problems.

 

[Joe Reeves]

Re: Runs on muffs, dies in water

If you have compression (do you?) and spark, and the carburetors are not fouled, you may have the idle set too low. On a flushette, the idle on a flushette (hose) should be:<br /><br />20" shaft engine = 1000 rpm<br /><br />25" shaft engine = 1200 rpm

 

[garyinva]

Re: Runs on muffs, dies in water

I will check compression and rpm and get back to you. Not sure what points I clip Tachometer to. Can you help? I will also check back logs. Thanks

 

[Joe Reeves]

Re: Runs on muffs, dies in water

How many wires lead from the tachometer and what color are they?

 

[garyinva]

Re: Runs on muffs, dies in water

Scratch eveything. Did some more checking after reading some past entries. Pulled plug wires while engine was running and discovered it's running on 1 cylinder. Guess that explains the lack of power.(duh) Didn't have a clue it could run so well on 1 cylinder. My 2 bad cyld. plugs have a grayish goo on them. Looks like there might be moisture, not sure. They are getting spark. Do you think it's the head gasket, or could it be carbs? sorry to be such an idiot. I will still check compression as soon as i can get a gauge from a buddy. Thanks

 

[Joe Reeves]

Re: Runs on muffs, dies in water

I suggest you remove the cylinder head to inspect the piston, inside dome area of the head, head and block sealing surfaces, as well as the head gasket.