1995 Force 90 - fuel delivery issue?

[Bannister 6905]

The saga of the Force 90 continues...now that I've all the gremlins previously noted fixed, another one has popped up.
The motor starts immediately and idles well. After about 30 seconds, it leans out and stalls. I pump the bulb until hard (i can hear it filling the carb bowls) and it immediately restarts. I take off and it accelerates and cruises smartly with no issues. Then, I stop, shut the motor off for a bit and try to restart after a pause. The bulb is not "soft", but is certainly not "hard" and the motor will not start. I pump the bulb several times, hearing the carb bowls filling and the motor starts and runs well again. There's no hint of the bulb collapsing at any time.

I have replaced all the fuel lines, rebuilt the fuel pump, replaced both fuel pump manifold gaskets, cleaned the filter and made sure the carbs are clean and adjusted properly. The only thing I haven't replaced is the bulb, although I did clean it out thoroughly.

I have confirmed that I rebuilt the fuel pump properly, all connections are tight and there are NO leaks and no flooding.

Has anyone else had a similar issue and what was the fix?

Thanks.

Bannister

 

[Redbarron%%]

Try putting a TEE in the fuel delivery line to the carbs and a pressure gauge to see id that pump really delivers fuel, regardless of the rebuild.
Measure and don't guess and a logical process will find the problem.
Possibly the bulb is bad, but the pump should be pulling fuel through it
Measure, don't guess.
By the way a leak that let air get into the line will keep a pump from pumping as the pumps are made to pump liquid not air.
Especially on the suction side of the pump.

 

[Tassie 1]

made sure the carbs are clean and adjusted properly. The only thing I haven't replaced is the bulb, although I did clean it out thoroughly.

Thanks.

Bannister

slighty confused...
does that mean you have dismantled the carb completely, soaked all the bits and bobs in carb cleaner etc etc and then used compressed air to blow out any crap in various jets/passages then put it all back together with new gaskets?

how does one clean out a primer bulb?

also, did you change the fuel pump diaphragm?

 

[Bannister 6905]

Both of you have great suggestions - I will start with verifying that the pump is actually pumping and will advise later. What would an acceptable pressure be from the pump to the tee?
As for the other questions, yes, I thoroughly cleaned and reassembled the carbs with new gaskets. FYI, they were very clean before I did my cleaning. Cleaning a primer bulb, well what I do is rinse for both ends with clean gasoline and then drain onto a paper towel until the fluid comes out clean-looking. Yes, my pump rebuild included the diaphragms.

 

[Tassie 1]

Thanks for that,
had never thought of giving a bulb a good cleaning before
Have only chucked 'em in the bin when they start feeling dodgy,

 

[Bannister 6905]

Mine is in excellent condition - just had ben idle for months and the old fuel took a toll - pretty grungy. If not in nice condition, I'd have tossed it, too.

 

[Bgbbgb246]

I had a problem kind of like this in my boat and it seems that I may have traced it down to the fact that the pickup tube that is inside the tank was actually pressing against the bottom of the tank thus making it hard on the pump to bring fuel up. I know this is kind of a stab in the dark but it is worth a shot if you've had no luck with anything else

 

[jerryjerry05]

The bulbs only job is to draw fuel from the tank and push it into the carb bowls and the
primer system.

IF?? the ball doesn't get hard??? then there's a part of the system that's bleeding through.
The ball, even a new ball can be bad right out of the box.
Pinch off the lead to the primer and then pump it up.
That make no difference? then the diaphragm in the pump is bad or the squeezie's bad?
The diaphragm and the plastic check valves can go bad in 1 second.
One backfire or cough can blow a hole in the diaphragm or bend the check valve??

These are low pressure pumps and put out 1-3# psi max.

The primer has a diaphragm that can go bad from age and ethanol use.

You posted: "

After about 30 seconds, it leans out and stalls."
This could be the pumps not pumping or it's possible the prime system's
overloading the system and flooding the motor.
Try this: after it starts, pinch off the leads from the primer and see if it dies?? ​

Older tanks can have crud build up and it can block the pickup.
Pull the sending unit and see how dirty the bottom of the tank is?

 

[Bannister 6905]

The bulbs only job is to draw fuel from the tank and push it into the carb bowls and the
primer system. Understood, but if it leaks, it would cause problems running. Mine's not leaking.

IF?? the ball doesn't get hard??? then there's a part of the system that's bleeding through.

The bulb gets hard. I've checked the entire system for leaks and have found none. In fact, if I let the boat sit overnight after pumping the bulb, it's still fairly hard the next day - takes maybe 2 squeezes to get it hard again.

The ball, even a new ball can be bad right out of the box.
Pinch off the lead to the primer and then pump it up.
That make no difference? then the diaphragm in the pump is bad or the squeezie's bad?
The diaphragm and the plastic check valves can go bad in 1 second.
One backfire or cough can blow a hole in the diaphragm or bend the check valve??

The diaphragms are both good. The check valves are rubber and plastic...how could they "bend"?

These are low pressure pumps and put out 1-3# psi max.

I'm checking it tomorrow, when I get the gauge.

The primer has a diaphragm that can go bad from age and ethanol use.

You posted: "
After about 30 seconds, it leans out and stalls."
This could be the pumps not pumping or it's possible the prime system's
overloading the system and flooding the motor.

It's leaning out. If I pump the bulb just when it starts to die, it resumes running well.

Try this: after it starts, pinch off the leads from the primer and see if it dies??

Older tanks can have crud build up and it can block the pickup.
Pull the sending unit and see how dirty the bottom of the tank is?

Bottom of the tank is clean and the pick up is just off the bottom.

 

[jerryjerry05]

You posted
"It's leaning out. If I pump the bulb just when it starts to die, it resumes running well."

It's not leaning out, it's running out of fuel.
This tells me the pumps not working and when the balls squeezed again the motors running off the fuel you squeezed
up into the bowl.

The square pumps can be put together wrong and look right.
The check valves can bend when installing the pin that holds them in place??

Take the pump apart and lay the plastic wafers on a mirror and see if they're flat?

 

[Bannister 6905]

It is leaning out - not getting fuel. Either too much air or too little fuel can cause a lean condition.
Anyway, I found the problem by doing the pressure test you suggested - zero fuel pressure...
The pump had been previously "overhauled" and I assumed he knew what he was doing. So, when I reassembled the pump, using exactly the same parts that were in it (however new ones), I also left out the rubber discs on the check valves.
New parts are to arrive tomorrow and that should fix the lean condition. Thanks for your input and help.

Bannister

 

[jerryjerry05]

Let us know how it works?

 

[Bannister 6905]

Issue resolved - rebuilt the fuel pump with ALL required parts and it now runs perfectly - very pleased!

Thanks for all the suggestions and advice!

Bannister