rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

[justmop]

where is the rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor.. i need to know i think mine is split because i am dumping alot of fuel out but dont know where its going i need to know asapo thanks

 

[maverick974]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

Oooooh! I know this. I had the same problem not long ago. The diaphram is located on the passenger side just below the coils. Look for the round fuel filter with the large silver screw. That fuel filter is actually bolted to the diaphram housing.

 

[justmop]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

cool iam going to go look now i am dumping alot of fuel right now i think that might have a split in it

 

[justmop]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

is it easy to change and where did u get the gasket from

 

[maverick974]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

Any boat place will have those or can order them. They are cheap as well. A couple of years ago when it happened to me, my fuel pump diaphram cost me under 3 dollars.
If for some reason you can't find one, I'm sure they are available online as well.

 

[justmop]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

so how easy is it to change it looks like to me its just 5 screws .. so with that being bad would that make the gas come out of the exhaust...

 

[roscoe]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

Yes a bad diaphram will dump fuel.

The old ones rotted from the ethanol in our gas.
The new ones are ethanol resistant.

You can got aftermarket kits here on iboats, or get a factory kit from any Mercury dealer.

The factory kit usually comes with an instruction sheet. Or at least they used to.

 

[maverick974]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

so how easy is it to change it looks like to me its just 5 screws .. so with that being bad would that make the gas come out of the exhaust...

It is just 5 screws. Take 'em out, pull off the diaphram, put in the new one, install 5 screws, sit down with a cold one and congratulate yourself on a job well done.

 

[justmop]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

so i guess the diaphram is a gasket to ....if it clears up today i am running down to the boat to change it ... so did u notice a difference in the motor after changing it

 

[maverick974]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

so i guess the diaphram is a gasket to ....if it clears up today i am running down to the boat to change it ... so did u notice a difference in the motor after changing it

Well, no, it's not really a gasket but it's installed like one. I had a pin hole in mine and it ran horribly. I took it to 3 different mechanics and they couldn't figure it out. Once I finally found what it was and what it did, I changed it and it made all the difference in the world. With a bad diaphram, it leaks fuel directly into the cylinders and no matter what you do, the engine will run extremely rich. So rich that it hardly runs at all. I changed the diaphram and it instantly ran perfectly.

 

[foodfisher]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

You will probably have to reset your idle speed.

 

[justmop]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

well i just changed it and ran it for a test run it seem to run alittle better but it seem like the motor ran the same ...the only way i guess i can figure it out to see if its dumping alot of fuel is to take it for a long run... whats the normal constumpion of fuel burn i have a 7 gallon tank do i need to get a bigger one .. i didnt think i would burn 7 gallons in 4 miles

 

[foodfisher]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

If your running against a 30 mph current or better.

 

[justmop]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

what do u mean 30 mph current

 

[foodfisher]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

I mean, it takes more fuel to go 4 miles upstream (against the current) as it does to go 4 miles against no current. Even less going downstream. How long did it take to burn 7 gals. going 4 miles?

 

[justmop]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

about 25 min

 

[foodfisher]

Re: rubber diaphragm in the fuel pump on a 1986 85hp forces outboard motor

Figure one gal. per hour for every ten hp. @ wot as normal. An 85hp should burn 8-9 gals. per/hr. Your numbers put you in the 16 gal/hr range. You've got some issues to deal with. Start w/ the link and sync sticky.then get back with specific items. The diaphram can be torn on installation if a burr on a screw grabs it and twists it as you tighten.