Motor cranks but quits unless I hold the tank above to motor

[BROUSSARD2]

Someone help please. Ive worked on motors for years, but Im baffled. I have a 1974 Johnson 25 HP that I have restored. The motor cranks but quits unless I hold the gas tank above to motor. When this first happened i thought fuel pump. Bought the kit, and replaced the springs and gaskets. Same problem. Have replaced the fuel line to the carb and the fuel line from the tank. Any thoughts or help is much appreciated.

 

[oldboat1]

Had the same situation with an early 70s 6 hp, and it was the pump. You might consider buying a cheap replacement and see if it works. If so, save the current pump for parts.

 

[todd281]

Some fuel tanks,[even the remote ones] have a screen type filter inside. check it see if yours does. Also the fittings on the tank and motor end of you supply line, they sometimes have small "o" rings that go bad, then they leak gas or suck air, Good Luck

 

[flyingscott]

What happens if you pump the primer ball instead of holding the tank up?

 

[Crosbyman]

that pump is real tricky to back together.... did you do a pump test by blowing air into the fuel inlet and checking the out for proper air flow....


doing the reverse out to in should let no air pass in the pump pump gasket behind the pump is in place?

http://www.leeroysramblings.com/Rebuilding_fuelpump.htm

 

[BROUSSARD2]

What happens if you pump the primer ball instead of holding the tank up?

If I keep priming the bulb it will stay cranked. I will take the fuel pump apart again tonight to see if I made a mistake putting the it back together.

 

[BROUSSARD2]

that pump is real tricky to back together.... did you do a pump test by blowing air into the fuel inlet and checking the out for proper air flow....


doing the reverse out to in should let no air pass in the pump pump gasket behind the pump is in place?

http://www.leeroysramblings.com/Rebuilding_fuelpump.htm

Great info! Thanks. I will test this tonight. Im not immune to mistakes. Could be my fault.

 

[Crosbyman]

when I rebuild them I put a small dab of crazy glue on the spring's bottom to stick them upright on the mating nipples

I do the same on top where the mushroom fits so it stays in place while I stack the layers otherwise the spring/nipple falls down or flies away :fear:


and by the way assuming you reassembled it ok.... before taking it apart scratch the side or make a permanent ink mark to help realign the layers the same way when you rebuild it.

read the doc 2-3 times and understand it ... it can be confusing

 

[BROUSSARD2]

Thanks to all who chimed in and helped here. I used the recommendations. Went back over the manual, using the link provided. I had the out flow nozzle in the wrong direction. When I used your advice and blew into it freely, I knew I had done something wrong in the rebuild. Much thanks, its running like a charm.