Fuel Pump Test?

AGENT 37

Petty Officer 1st Class
Joined
Mar 2, 2007
Messages
319
1999 75HP Enduro -

I just saved this outboard from the dump. The owner said it was overheated and running rough before it died.

Turned out that it was not reliably firing on one cylinder due to a damaged wire going to a coil. I cut and repaired the wire and got the outboard running fair. I found the outlet going from the water jacket to the tell-tale plugged; I cleared it and got the motor properly indicating cooling.

Not being mechanically inclined, the combination of these things probably had the previous owner thinking that the engine was toast. I conducted a de-carb and the power head now has an even 90 psi on all three cylinders.

It initially starts and idles well. If I increase RPMs for a minute and then back it off, it runs rough and eventually stalls. I've adjusting the pilot screws and either had no change or made it slightly worse...... it can be hard to tell when you don't get the results you're after. If I pull the choke it stalls out; even with the screws adjusted to what would be a lean setting. She's certainly running rich..... with the top cylinder being driest and firing strong.

How can I test the fuel pump before replacing? Does it sound like I'm on the right track?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Fuel Pump Test?

Remove pump from motor but leave hoses connected, pump primer bulb, check for fuel leaking out of the back of pump, indicating a bad diaphagm. My motor is a 1999 and I just put a new fuel pump($45) on for the first time, nothing wrong with the old one, kept it for a spare...figured 12 years was enough and why just wait for it to die down the river somewhere? Good Luck!
 
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