4hp Johnson keeps loosing priming pressure

mainejohn

Petty Officer 2nd Class
Joined
Jul 24, 2009
Messages
107
my 4hp Johnson keeps loosing prime and motor dies or I have to keep squeezing the primer ball. It will run about 1-2 minutes then dies. No fuel is leaking. Could it be the fuel pump diaphragms?. Please help , I want to go fishing
 

joelybob

Petty Officer 1st Class
Joined
Jun 30, 2012
Messages
224
Re: 4hp Johnson keeps loosing priming pressure

I am having similar problem with my 4.5 hp evinrude except mine is leaking gas. think mine is fuel connector. listen real good for air leaking sound you could have same problem. just a guess though. good luck
 

james__12345

Petty Officer 2nd Class
Joined
Jun 26, 2012
Messages
196
Re: 4hp Johnson keeps loosing priming pressure

Is the vent cap on the gas tank open? That will cause a motor to die after a couple of mins, because the pump cant pull against the suction in the tank.
 

bonzoscott

Senior Chief Petty Officer
Joined
Jul 26, 2008
Messages
745
Re: 4hp Johnson keeps loosing priming pressure

Having to keep squeezing the hose bulb to keep it running is a tell tail sign of fuel pump problem. Rebuild kit ~$20, and look up Leeroy's Ramblings - fuel pump. Tell's you how to rebuild fuel pump. Read it first, then dis-assemble pump. You may just have some crud in it and just need a good cleaning.
 

Crosbyman

Rear Admiral
Joined
Nov 5, 2006
Messages
4,912
Re: 4hp Johnson keeps loosing priming pressure

Open the tank cap and lift the tank above the engine after you start it. If it run's good the fuel pump is probably shot or simply malfunctionning ...time to check it out

Rebuilding the OMC Fuel Pump

Check the tank vent !!

"Priming" is something you do to fill the carb bowl ....after it is kept filled by the fuel pump doing the rest of the work !

If the engine dies with cap off & the tank above the engine ...look for fuel restrictions (incl bad pump) and fuel drips which would indicate air leaks.
 

mainejohn

Petty Officer 2nd Class
Joined
Jul 24, 2009
Messages
107
Re: 4hp Johnson keeps loosing priming pressure

I ordered the rebuild kit. Hopefully it works
 

Crosbyman

Rear Admiral
Joined
Nov 5, 2006
Messages
4,912
Re: 4hp Johnson keeps loosing priming pressure

here is my repeat story...

to rebuild ...read read read and understand the sheets

to assemble the springs and the little plastic mushrooms (domes) just put a small dab of crazy glue on the bottom of the springs and a small dab on the mushrooms .

Mount/glue the mushrooms on the springs mount the springs/mushroom assemblies on their mating positions

cover up with the diaphragms hope for the best and do a blow test in to out but no air out to in

the crazy glue will keep ypu from going crazy and stop the parts from fly out ....work on a CLEAN table over a flat floor (no cracks!!)
 

mainejohn

Petty Officer 2nd Class
Joined
Jul 24, 2009
Messages
107
Re: 4hp Johnson keeps loosing priming pressure

i fixed the issue!!!!!!!!!!!!!!! i rebuilt the fuel pump and works great!! watch out TROUT!!!!
 

Rick.

Captain
Joined
Jul 30, 2006
Messages
3,740
Re: 4hp Johnson keeps loosing priming pressure

Glad it worked out for you. Best of luck. Rick.
 
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