Preventative maintenence question.

[Michael Lang]

I am finishing up going through a 1991 70 hp force and want to know if rebuilding the fuel pump (valves and diaphragm), is considered normal preventative maintenance. I have a original service manual and looks easy enough and the last time I used the boat it consumed about six to seven gallons of fuel in a hour at wot for 70 percent of the hour, I guess that is. about normal by rule of thumb.

 

[jerryjerry05]

Re: Preventative maintenence question.

The rebuild,the valves don't usually go bad.
The rubber diaphram should be replaced every few years,or not.
Some believe if it's not broke,don't fix.
I went through the pumps on mine as one had started leaking.
It needed a gasket.The diaphram was changed anyway.
The second one I rebuilt anyway.
When I took it apart it had 2 diaphrams and no gasket??
It ran fine.
6-7 gal at WOT for an hour,depending on boat size,load,prop,it sounds about right.
My boat, I get about 2.1 miles a gal.
Actually pretty good for twin 85's

 

[Michael Lang]

Re: Preventative maintenence question.

Quick update, diaphragm was brittle, peeling and had a few pin holes. Question: Will I see some improved gas performance, I always felt that the 70 hp used to much gas.
Thanks for your previous reply jerryjerry05

 

[roscoe]

Re: Preventative maintenence question.

You should see a little improvement.

I always thought my 70 was good on fuel.

Running it at 3/4 throttle (4000 rpm) will save you a bunch of fuel.