88 Force 85 hp Fuel Pressure/Pump issue

[dngbt5]

This is my first post and I am new to the whole boating culture. I love working on my own stuff, but dont know much about Outboards. I have an 88 Force 85 hp outboard mounted on a Capri 1700.
This motor fires right up and planes out fine. I runs 30mph for about 5 min and then it bogs down. If I squeeze the fuel bulb the motor evens out for a short while, but thats it. The harder I squeeze the better it runs. I also noticed that the longer I ran the motor it got worse. I have replaced the impeller recently so it should be pumping water fine, doesnt seem hot.
I am thinking that somehow it is losing prime. I tightened all fuel line connections and still had the prob. I am now thinking it may have to do with the fuel pump. However I have read some threads on here where members have replaced the whole pump to no avail. I was wondering if I should start with the diaphram and seals for the pump or the whole pump?

 

[foodfisher]

Re: 88 Force 85 hp Fuel Pressure/Pump issue

Diaphram and check valves.

 

[huskerdaninva]

Re: 88 Force 85 hp Fuel Pressure/Pump issue

I agree, but would also re-plumb all of the fuel lines w/ new clamps too and of course a new primer bulb. Good luck...

 

[Doernuth]

Re: 88 Force 85 hp Fuel Pressure/Pump issue

Check the tank vent. If it is blocked can create a vacuum in the fuel system. A good sign of this is the prime ball colapsing while running.

Also if your tank is equipped with an anti-siphon valve check that they can be problematic.

 

[jerryjerry05]

Re: 88 Force 85 hp Fuel Pressure/Pump issue

That boat has a built in tank.It has a vent line.It could be clogged with insect nests(mud dauber)and dirt.
Check this line first.Do it from the tank out as you can push crap into the tank.
Then worry about the fuel diaphram.The diaphram is usually the culprit.If the valves are rusty or corroded they might be bad. Do a compression test.
Just for GP replace the impeller.