1961 Johnson 10hp - QD-22 - Fuel Pump Issue?

[ScottyOMC]

Hello,
This is my first time working on an outboard so my apologies if I’m missing something.

I just bought a 1961 Johnson 10hp QD-22 motor. Guy said it hadn’t run for a couple years. I took apart and cleaned the carb, checked the coils, checked the compression (about 80-90 on top cylinder, can’t get my gauge on the bottom on because of the size of the gauge) put in new sparks, and got the motor running and ran a few litres of gas with sea foam through it.
Only issue is the motor will only run when the gas tank is elevated. I put the gas tank on top of garbage cans so it’s above the motor and then it runs fine. When I put the tank on the ground, it runs for 30 seconds and then dies.
Is this definitely the fuel pump? Anything else I should be testing or looking at. Any suggestions for testing the fuel pump?
Thank you very much!

 

[oldboat1]

Fuel pump diaphragm. They get dry/stiff and take on a set -- new ones are flexible. Replacement pump is the small square one 0388685, I believe. Big believer in oem parts, but the cheap foreign pumps on the market seem to work fine at maybe 1/4 price or less.

 

[Crosbyman]

ground to pump.. 2-3 feet . may be a bit high

have you tried a normal 12 inches or so... if ok pump is good ..for now

 

[oldboat1]

^^point is good. Get a fresh pump for backup.

Btw, water in your test tank should be comfortably above the water pump.

 

[ScottyOMC]

Thank you all for the feedback!
Got the problem fixed! The note about the diaphragm got me thinking more about the fuel pump. When I first got the motor earlier in the week I opened the fuel pump to clean it up and I must have put a spring back in the wrong spot.

 

[oldboat1]

Good news! (and no $$ spent.)