Force 50 cuts out, fuel pump gasket leaks, poor start

[inquizito]

After cleaning carb-replacing fuel pump diaphragm and installing in-line fuel filter (and checking fuel pump screen filter) on 1987 50 HP 507F7-C, the motor continues to cut out: began only at W.O.T. and gradually lower rpm cutout until it became very hard to start and stalls unless I squeeze the bulb or choke by pressing ignition key in continuously. Do I need a new fuel pump?

 

[inquizito]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

Should also add that I rebuilt the carburetor too and that the fuel pump diaphragm leaks when I squeeze the prime bulb, whereas before if too much fuel was pressurized, it would leak out of the front of the carburetor, as normally would. More problematically, and seemingly indicative of fuel starvation, is fact fuel continues to spurt through fuel pump diaphragm as it tries to run. The tank is vented and there is no fuel separator installed to further impede the flow of fuel on a short, 5' line with only a small in-line filter.

 

[inquizito]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

And it will only get going if I quickly pop into forward and start hitting squeeze bulb or choking.

 

[inquizito]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

Lastly, I did tighten the screws securing the fuel pump diaphragm to make sure they were secure.

 

[jim dozier]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

I am not familiar with the exact concstruction of the force fuel pump but they all work on the same principle and NONE of them should leak under any circumstances. Also, fuel should not spew out of the carb throat even when you pump the fuel bulb, thats what the float valves are there for. Either you didn't adequately rebuild the fuel pump or there is a flaw in the mating surface that is preventing the new gasket from seating in which case a new fuel pump would be in order. You may need to revisit the carbs also if they are still leaking. If you go back into the carbs, do thorough cleaning with carb cleaner and compressed air and replace the float valves, set them to spec and use new gaskets. Your engine is sucking air not gas and is dying for lack of fuel.

 

[scotiany]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

I would only add to jimd's reply that for the price of a carb rebuild kit at NAPA, you should replace the needle and seat assy. in the carb. I would also remove carb and thoroughly soak it in a carb cleaner, blow it out and reassemble.

 

[inquizito]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

thanks to you both for your capable assistance. Checking it today, I pulled the fuel pump apart and found a valve requiring two small 3/32 x 1/4 head bolts that should have been inserted into holes on either side of it, jostling around with the valve - had ripped through the diaphragm and created the leak it would be obvious assessment.<br />I got stranded in 3-5' chop with a friend with this and paid a 'technician' for this substandard workmanship. Of course same night, my lights went in pitch black, and the battery died. And a barge almost hit us in the intracoastal waterway.<br />Back on track, the diaphragm is the culprit right?I don't know how it ran as long as it did without that second position valve jumping out of place and penetrating the diaphragm. I am supposing that it would be folly to mend the diaphragm, although the tear is only about 1/8" vertically and 1/16" horizontally. Have rubber and thought I could simply melt onto the surface and mend it. Also, I notice that the valves are designed to allow their metal encasement which holds the spring and rubber valve in place to spin around; however, mine do not spin freely, one not at all. Is it imperative to the proper function of the valve for the encasement to spin unhindered to supply fuel adequately and allow valve motion?

 

[scotiany]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

If your diaphagm is like the Chrysler one, you can get the kit at NAPA for less than $8. DO NOT use any kind of sealer on it. However, if you want to use loctite on the mounting screws, that's OK. Also, if you go to NAPA, think about getting some fuel hose for your motor. It's cheap and easy to change.

 

[inquizito]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

Thanks. The carb has been rebuilt, so hopefully won't see fuel in the throat of it, nor from the leaking diaphragm. Picking up a new diaphragm at the local Force dealer here along the NC Coast for $3 - the other gaskets are new, and the valve that requires a gasket, I moved from its improper location to where it belongs according to the manual - in the intake transfer valve leading to the second chamber pumping to the carburetor - incidentally, the one the guy didn't replace the screws on that ruptured my diaphragm jostling ...Off to the dealer to see if he'll provide a new diaphragm no cost seeing as how he failed to install the failing one properly, and left me stranded - and it could have been worse. I believe the springs on all my valves are tight, and the system works well, only allowing passage of air from one valve into the next -no backflow, so I am assuming same will be said for the fuel. I wonder why there have to be valves and not simply the passages leading from one chamber to another - do valves force greater flow pressure? Do they monitor volume and force of fuel flowing?

 

[scotiany]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

They are check valves. They only allow the fuel to go one way and not back up when the diaphragm changes direction.

 

[jim dozier]

Re: Force 50 cuts out, fuel pump gasket leaks, poor start

Ditto scotiany, the fuel pump is connected to the engine crankcase. When the crankcase sucks (piston upstroke) fuel is sucked into the fuel pump through 1 of the 1-way check valves. When the crankcase blows (piston downstroke) the fuel now in the pump is forced through the other 1-way check valve to the carb. Suck-blow, suck-blow, etc. Your broken fuel pump just sucks