150 pro V fuel vaccum issues

bassndux

Recruit
Joined
Jan 24, 2008
Messages
4
To any that can help,

I have a 1987 ProV 150 on a 18' Ranger bass boat that has a unique problem. The motor creates a vaccum in the fuel line, sucks the bulb in tight and will bog down and I will get wet. This only happens when I get to a half tank of fuel (the boat has twin 14 gal tanks). If I switch tanks quickly the bulb will come back immediately as well as the rpms. I am then good for 7 or so gallons on that tank. Sometimes I can go back to original tank and run around 3-3500 rpm and be OK, but usually not long after I increase back to around 4500 rpm (my usual crusing speed) the bulb will suck in tight again.

Here is what I have done. I've change the fuel filter, fuel pumps, spark plugs (twice) and fuel line (from ff to tank switch and to each tank). I've taken the sending units out of both tanks to check the screens and they were clean as were the tanks.

I haven't done anything with the carbs yet. Could they be the culprit??

Thanks to anyone who has any ideas.

Rick
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: 150 pro V fuel vaccum issues

not unique at all, rather common.
you simply have a restriction between the fuel primer outlet and the liquid level in the fuel tank, find it and you quit getting wet.
if it was between the primer outlet and a fuel bowl the primer would never have enough vacum to suck flat but the engine would stil die.
see how simple trouble shooting is?
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
Re: 150 pro V fuel vaccum issues

Check to see if the vents to the tanks are open.
 

bassndux

Recruit
Joined
Jan 24, 2008
Messages
4
Re: 150 pro V fuel vaccum issues

Thanks for the replies. I've changed the fuel lines to both tanks previously and the vents on both tanks are clear. The fuel switch will probably be the next item I change. Rodbolt, I'm trying to keep it simple, thanks for the ideas.
 
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