1982 80hp merc losing fuel presure

[cbaldy71]

I just got my boat, it has a 1982 80hp merc on it. Starts up fine, runs great at a idle, when i open it up i lose fuel pressure in the bulb and it dies. If i pump the ball while i have it opened up it runs fine. If i back off the throttle when it starts to die it will keep running and the pressur does build back up after 5 plus minutes and then i able to open it up again, but only for about 2-3 hundred yards at a shot. Please help

 

[cbaldy71]

Re: 1982 80hp merc losing fuel presure

I did replace the fuel line, tank, and the conections.

 

[roscoe]

Re: 1982 80hp merc losing fuel presure

Either the fuel pump needs a rebuild kit, or the needle valve on the carb float is not opening up soon enough/far enough. Needs a cleaning.

I would do the fuel pump first, as the ethanol in our gas has been rotting away the diaphragms in the fuel pump.

 

[BoobieBouncer]

Re: 1982 80hp merc losing fuel presure

I would try the fuel pump frist also...

http://forums.iboats.com/showthread.php?t=311655

 

[hkeiner]

Re: 1982 80hp merc losing fuel presure

when i open it up i lose fuel pressure in the bulb and it dies

If rebuilding the fuel pump does not solve the problem, keep in mind that there is never actually any fuel pressure in the bulb. The fuel pump sucks fuel through the bulb. If the bulb is collapsing or very soft when the motor is running, this may indicate a restriction upstream of the bulb or a faulty check valve in the bulb i.e., check valve does not allow fuel to freely flow through the bulb when the motor is running at high RPMs. A fuel vacuum gauge is a good tool to troubleshoot this type of problem.

http://forums.iboats.com/attachment.php?attachmentid=26607&d=1240244928

http://forums.iboats.com/attachment.php?attachmentid=26608&d=1240244937

http://forums.iboats.com/attachment.php?attachmentid=26609&d=1240244945

http://forums.iboats.com/attachment.php?attachmentid=26610&d=1240245079

 

[cbaldy71]

Re: 1982 80hp merc losing fuel presure

thanks for the info...will be rebuilding the fuel pump this week but will check the bulb first

 

[Ware5150]

Re: 1982 80hp merc losing fuel presure

I think you are on the right track but just wanted to share some info I have experienced. I replace my fuel line and bulb (Kit). I was running out of fuel and had to keep pumping the bulb. I used my compressor and around 40psi to pressurize the fuel lines. (off the boat). I found a small leak (Factory Defect) where the line connects to the bulb. I fixed the leak and fuel stays full.

 

[cbaldy71]

Re: 1982 80hp merc losing fuel presure

ok i rebuilt the fuel pump, replaced fuel line and bulb again...same problem.runs fine at an idle and at half throttle but if i open it up it cuts out after about 2 or 3 hundred yards. It seems to run out of fuel. If someone keeps pumping the ball it runs just fine....Please help

 

[BoobieBouncer]

Re: 1982 80hp merc losing fuel presure

I would check the carb float levels.

If you have the time and the skill you should clean and rebuild the carbs while you are in there.

Just my two cents...

 

[hkeiner]

Re: 1982 80hp merc losing fuel presure

You seem to have covered the basics. I suggest using the vacuum gauge tests to figure out what is going on.

 

[Showtime22]

Re: 1982 80hp merc losing fuel presure

I'm not an outboard guy but I'm guessing the fuel pump is mechanical.
Is there an electrical fuel pump conversion available?

After hearing of the mystical electric fuel pump I finally put one on.
I bought a universal electric fuel pump from NAPA for my inboard. 45 bux.
I ran it far away from any heat sources and its helped my boat a lot.
I have heard some guys run two pumps. Electrical pushing to the mechanical...

A rebuild would not effect a vapor lock problem.
The carb is suspect also.

 

[hkeiner]

Re: 1982 80hp merc losing fuel presure

Installing an electric fuel pump to replace a mechanical fuel pump is not good idea. It is dangerous because the electric fuel pump keeps running if the motor stalls, due to a broken fuel line or similar, and the pump is not turned off. A mechanical fuel pump stops pumping as soon at the motor stops, no matter the reason. Finding and fixing the current problem with the motor is the way to go.

 

[Ware5150]

Re: 1982 80hp merc losing fuel presure

I would and have installed a inline clear fuel filter. (Walmart) This will allow you to see if you are losing fuel or is it another problem. Just a cheap way to keep your carbs clean and test fuel issues.

Install along fuel line past the bulb.

One more thing I just thought of. You could have some restrictions in the gas tank air vent. Im sorry if you already said this but just thought of it.

 

[BoobieBouncer]

Re: 1982 80hp merc losing fuel presure

You could have some restrictions in the gas tank air vent.

Good call. That's an easy and free thing to check.