1993 40HP only working with primer, mystery problem

[cenkaetaya]

Hi, I have a 1993 40HP and it will run with primer pressed over and over, or if i hold my 2 hands over heads Carb air intake and constrict airflow; but otherwise I cannot get it to run.

I have tried different carbs, I have a few sets of these same engines, I have 2 fuel pumps, I tested, currently a new one, and the engine runs perfectly when engaging the primer, but otherwise it dies pretty much instantly.

Compression us 100, 100, and if i hold my 2 hands over the carb air intakes, it runs well, but if I install an airbox, or anything other then using my hands it dies pretty much instantly.

Anyone have any ideas?

Thanks

 

[cenkaetaya]

Images of the motor:

 

[boobie]

Have you been into the carbs and taken them all the way apart ??

 

[cenkaetaya]

Yes, and i have like 3 sets, they all end up having this same issue, all 3, primer works otherwise doesnt.

I only at the last second thought to try running the engine with hands covering the intake holes. With my friend turning the ignition. It seems to run perfectly, but the second i moved my hands it died.

It just seems so strange how no matter what I have tried, hoses, pumps, carbs, Its always the same result, engine sounds like new as long as you add primer.

 

[racerone]

The primer puts fuel into the motor.----This fuel bypasses the carburetors.-----That strongly suggests you need to revisit carburetor work.

 

[cenkaetaya]

The primer puts fuel into the motor.----This fuel bypasses the carburetors.-----That strongly suggests you need to revisit carburetor work.

What about the fact that having my hand over the air intake makes it run? does that suggest the carb isnt clean enough to pull the fuel through itself?

 

[racerone]

That would make for higher vacuum to pull fuel out of the bowl.-----Are the gaskets in place around the nozzles ??----Did you remove the high speed jet in the BOTTOM of the float bowl to make sure it is clean , yes or no ??

 

[boobie]

Read post # 3 again ??