After fire, engine revs good in neutral but very weak under load

swire

Petty Officer 2nd Class
Joined
May 11, 2004
Messages
131
I have a 1965 Evinrude 75HP Starflite IV electric shift motor that I've been working on all summer. I thought I had it running pretty good until it caught on fire...which turned out to be a bad fuel line. After replacing the fuel line and cleaning up the motor it does not have power under load. The motor starts fairly quick and sounds excellent if I rev it up in neutral but as soon as I put it in gear the motor struggles to speed up. It's running at about 1/3 the speed it used to. The only odd noise the engine makes is it surges slightly.<br /><br /><br />Here's what I've done so far.<br />Cleaned/Rebuilt the carbs...three times. I've gone through 2 cans of carb cleaner and a can of sea foam cleaning out all the ports.<br /><br />I check the primer bulb and it's fine. I tried pumping the primer bulb when the motor is running and it produces no result.<br /><br />Timing is set to the standard markings.<br /><br />I've replaced the spark plugs.<br /><br />Decarbed the engine.<br /><br />**** Before the Fire****<br />I put on a brand new coil<br /><br />Replaced the points and condensor<br /><br />Fixed some bad wiring<br /><br />Compression check, all cylinders came back at 92lbs.<br /><br />***Other things ***<br />The distributor cap looks brand new<br /><br />The altenator is charging the battery<br /><br />*** only thing not replaced ***<br />is all the spark plug wires. I have a little light that checks for spark and each cylinder is shown as having spark.<br /><br /><br />Is there anything that I have over looked that might cause this problem? Is there anything that I could go back and redo to see if I missed something or didn't get it quite right when I was working on it?
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: After fire, engine revs good in neutral but very weak under load

With the engine running at idle or a slightly fast idle, with insulated pliers, remove one spark plug terminal at a time.<br /><br />This would tell you via the response whether all cylinders are actually firing or not.
 

karrick

Petty Officer 1st Class
Joined
Oct 12, 2003
Messages
259
Re: After fire, engine revs good in neutral but very weak under load

I had a similar problem with my 4 wheeler last year. I know you said you cleaned the carbs, but the problem sounds like your main jets are plugged/clogged/full o' goo :eek: This is where I would go first. Good luck
 
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