1996 Evinrude 40hp - Will not idle, 6mph WOT

T

Th3gr3mlin

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Apr 28, 2023
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Hello!

I’m looking for some guidance with my outboard - having some issues with it.

Model is an E40TTLEDS

Engine starts up just fine, dies after idling for about 30 seconds. In gear, turn the throttle, max speed at 6mph (which is about a quarter where it should be). Pumping the primer bulb has no effect. Every once in a while it will surge RPM for a split second, then go back to the constant lower RPM.

I have cleaned & rebuilt the carburetors (they looked spotless when I opened them, but cleaned and rebuilt while I was in there). Changed the fuel line from tank into engine and primer bulb.

I have tried with different gas in a different tank as well, same results.

Compression is equal on each cylinder.

It was running mostly fine last season - with the occasional odd moment “bog” and sometimes wouldn’t idle fully.

The first time I took it out this season about a month ago it wouldn’t idle, but ran fine otherwise. Noticed it bog once momentarily- but was fine for the rest of the trip.

A week later - couldn’t get over 6mph

After rebuilding the carbs it appeared to idle fine on a hose in the driveway, on the lake the issue returned.

Trying to figure out where to look next. Replace fuel lines? Rebuild the fuel pump? Something else?

Thanks
 
R

racerone

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Dec 28, 2013
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38,802
What fuel pump is on this motor ?----Sounds like it is running on 1 cylinder.----Does spark jump a gap of at least 3/8"?
 
F

F_R

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Jul 7, 2006
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It almost certainly is running on one cylinder. But it is time to verify that (past time, actually).

Disconnect and ground one spark plug wire and start and run the motor. Then do the same, disconnecting and grounding the other spark plug lead. If it makes no difference with one grounded, but won't even run with the other one grounded the one that showed no difference is the one that is not running. Knowing that, zero in on that cylinder. Cleaning the carburetor or replacing the gas tank won't fix an ignition problem, for instance. It might be something as simple as a spark plug boot arcing out. Can't tell from here.
 
T

Th3gr3mlin

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Joined
Apr 28, 2023
Messages
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F_R said:
It almost certainly is running on one cylinder. But it is time to verify that (past time, actually).

Disconnect and ground one spark plug wire and start and run the motor. Then do the same, disconnecting and grounding the other spark plug lead. If it makes no difference with one grounded, but won't even run with the other one grounded the one that showed no difference is the one that is not running. Knowing that, zero in on that cylinder. Cleaning the carburetor or replacing the gas tank won't fix an ignition problem, for instance. It might be something as simple as a spark plug boot arcing out. Can't tell from here.
Click to expand...

Went out and got new spark plugs, just incase (old ones didn’t look fouled up and both were creating spark).

Both cylinders start up the engine independently of each other (removing the other spark plug and starting).

With both plugs in, the idle RPM sounds healthier on the hose in the driveway. I guess we will see when we get out to the lake next. Previously it was fine on the hose, but had lower RPM idle, but at the lake did not want to idle or reach a higher RPM in gear.
 
jimmbo

jimmbo

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May 24, 2004
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13,851
Running on the Muffs is a lot different than running with the boat in the water.
Examine the old plugs carefully. Any Cracks in the Insulator?
 
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