40hp fires, runs then dies

[stickysteve]

Just bought a 1993 40 hp evinrude fixer upper (sat for 3 years). Has great spark, kicks over (some times), runs for a few seconds then dies. Thought it was just bad gas. Put a portable tank with new gas still does the same thing. Primer bulb gets soft after running, and feels like air bubbles when i pump it back up. Runs a little longer if I keep pumping but still dies. Fuel saturated plugs after lots of pumping and cranking. Thanks

 

[quackaddict1]

Re: 40hp fires, runs then dies

Two thoughts, if the primer bulb is going soft, then you have a leak somewhere in your fuel line. Check the connections on your fuel line and at the fuel pump and carb(s).

When was the last time the carbs have been gone through? If you havent done it yet, get the kit(s) and do it, if sitting for three years, there is probably crap in the low speed circut. If you dont feel confident, have a tech clean them.

If the carbs are clean, I would suspect a bad fuel pump, another cheap and easy fix.

Go through your fuel delivery system and go from there.

 

[crxess]

Re: 40hp fires, runs then dies

Fuel pump or check valve in squeeze bulb.

 

[P 0 P E Y E]

Re: 40hp fires, runs then dies

Try a compression test...if you have a tester

or take the spark plugs out and slowly turn the flywheel to top dead center and look at the piston top...inspect for surface of the moon likeness.

A bad ring can sometimes stump you and cause erratic running

An other thing I found to help an engine that has been sitting (after making sure the fuel system is clean) is to put about two cap fulls of clean engine oil in the spark plug hole and turn the engine over to allow the oil to help the rings seal against the cylinder walls

 

[P 0 P E Y E]

Re: 40hp fires, runs then dies

Forgot to mention....

I have also seen a bad flywheel key cause all kinds of headaches.

If the key is compromised, it can effect ignition timing.

 

[stickysteve]

Re: 40hp fires, runs then dies

I have the rebuild kit already, just didn't want to open a can of worms if i didn't have to. I'm a industrial mechanic not a engine mechanic. But thanks for letting me know Im at least heading in the right direction. Theres gonna be some wrenches turnin this weekend !! One more question though, the manual says I need an OMC float guage but the rebuild kit didn't come with one. I searched the internet but cant find it. Will upside down and level work. SS

 

[stickysteve]

Re: 40hp fires, runs then dies

I do have a compression guage, as long as the cylinders are somewhat equal I 'm ok right? at about 100 pounds? The cylinder tops have some carbon on them but they don't look to covered, there are still bare steel spots.

 

[P 0 P E Y E]

Re: 40hp fires, runs then dies

Yes.......

If the float comes out without using a hammer, the float level should remain the same.

 

[P 0 P E Y E]

Re: 40hp fires, runs then dies

If you have not looked in the fuel bowl of the carbs....you should.

Sometimnes its best to look before you try to run it the first time cause it keeps all the poop low in the bowl and not sucked up into the smaller idle passages.

Take it apart I think there is 3 or 4 moving parts if you count the fuel.

 

[P 0 P E Y E]

Re: 40hp fires, runs then dies

85 to 100 is real good for that engine, especially if it has sat a while. if the two are witih in 15 psi your cool.

 

[P 0 P E Y E]

Re: 40hp fires, runs then dies

Forgot to warn you....


Make sure that you purge all old fuel from the fuel hose, inspect the tank and use fresh gas and quality oil before cranking, especially after cleaning the fuel system.

Look and understand how the fuel gets to the cab and make sure that the entire circuit is clean of old gas..

 

[Bugman1]

Re: 40hp fires, runs then dies

Just bought a 1993 40 hp evinrude fixer upper (sat for 3 years). Has great spark, kicks over (some times), runs for a few seconds then dies. Thought it was just bad gas. Put a portable tank with new gas still does the same thing. Primer bulb gets soft after running, and feels like air bubbles when i pump it back up. Runs a little longer if I keep pumping but still dies. Fuel saturated plugs after lots of pumping and cranking. Thanks

For starters I am going to agree with Quack, I think the problem may be in your fuel line. Invest $25 in a new fuel line/bulb assy, you probably need a new one anyway after 16 years. If you are feeling or hearing bubbles through your fuel line then you are probably sucking air in from somewhere. You should also clean both Q/D's (motor and gas tank) to make sure they are sealing properly, a quick brushing with a brass or stainless detail brush should do the trick, they will build-up corrosion which will make seating and coupling of the hose difficult at either end and you have an air/vacuum leak.

Since the motor has been sitting for a few years, you might expect some varnish and gum to have collected within the carb, you may get by with running some 110 octane racing fuel through the engine to clean out the ethanol sludge. Remember... Fuel and Spark....

Bug.

 

[kenmyfam]

Re: 40hp fires, runs then dies

For starters I am going to agree with Quack, I think the problem may be in your fuel line. Invest $25 in a new fuel line/bulb assy, you probably need a new one anyway after 16 years. If you are feeling or hearing bubbles through your fuel line then you are probably sucking air in from somewhere. You should also clean both Q/D's (motor and gas tank) to make sure they are sealing properly, a quick brushing with a brass or stainless detail brush should do the trick, they will build-up corrosion which will make seating and coupling of the hose difficult at either end and you have an air/vacuum leak.

Since the motor has been sitting for a few years, you might expect some varnish and gum to have collected within the carb, you may get by with running some 110 octane racing fuel through the engine to clean out the ethanol sludge. Remember... Fuel and Spark....

Bug.

110 octane !!!!!!
I would certainly not do that.
Why not just re-build the carb's and replace fuel lines with the ethanol resistant kind. Fuel system nice and clean, no racing fuel involved !!!