Fuel pump diaphram 88 Johnson

[surrender]

88 special fuel pump diaphram seems pretty deformed(stretched out). Could that cause motor to only run at half to full throttle(warm up lever) on hose for a couple of seconds then die? Motor has new stator, good spark all around, checked timing, and 120-125 compression all around. Just cleaned carbs again. but it wont stay running. It s like its only running on the fuel I prime it with by pumping the bulb and pushing the key in. I had fuel lines off carbs and cranked over and fuel comes out in pulses from the lines. Is that proper fuel pump operation? Bulb stays hard when pumped up. Dont know if motor will stay running while pumping bulb, havnt been able to get back to test quick enough before motor dies. Will recruit helper.

 

[ezeke]

Re: Fuel pump diaphram 88 Johnson

88 special fuel pump diaphram seems pretty deformed(stretched out). Could that cause motor to only run at half to full throttle(warm up lever) on hose for a couple of seconds then die? Motor has new stator, good spark all around, checked timing, and 120-125 compression all around. Just cleaned carbs again. but it wont stay running. It s like its only running on the fuel I prime it with by pumping the bulb and pushing the key in. I had fuel lines off carbs and cranked over and fuel comes out in pulses from the lines. Is that proper fuel pump operation? Bulb stays hard when pumped up. Dont know if motor will stay running while pumping bulb, havnt been able to get back to test quick enough before motor dies. Will recruit helper.

The fuel pump maintains the level of fuel in the float bowls. The engine vacuum pulls the fuel through the carburetors. Therefore, if the float bowls are full from using the primer bulb, it will take at least several minutes before the fuel in the float bowls is used up.

It is far more likely that you have enough fuel to fire from using the primer solenoid but that your carburetors are clogged and need to be rebuilt with good repair kits. Even if the carburetors are perfect, they will not function properly if the Synchronization and Linkage steps in your service manual are not followed.

 

[surrender]

Re: Fuel pump diaphram 88 Johnson

Was kinda a link and sync issue. When I replaced the flywheel I must not have torqued the nut enough(used a different torque wrench this time). So the Woodruff key sheared and flywheel turned about 25 degrees off. Once fixed and timing readjusted it idles great and starts right up on the hose. Will water test today. I had marked the flywheel for that reason but neglected to check that first, DUH. Would have saved about 3 hours of pondering and messing around with fuel pump and carbs. Lesson learned.

 

[wilde1j]

Re: Fuel pump diaphram 88 Johnson

The key sheared because the flywheel nut wasn't properly torqued. You get a few chances to get it right before the flywheel and crankshaft are junk.