Crushing Fuel Bulb

[arupert33]

I've been having issues most of the season with my primer bulb crushing flat when I run the motor (1988 150hp super 6) at more than low speed. Sometimes it will run on low speed for a couple minutes(less than 5) and others it will cut right out. Also, I noticed when I changed the primer bulb a couple times the motor would run at half speed for 5-10 minutes and would then cut out, and would never run at full speed. I have tried to run it with the gas cap open to check for vent problems and it didn't make any difference. When to motor cuts out, the fuel bulb is completely flat and almost never re-shapes without disconnecting it from the fuel line. Any ideas on what I could be looking at for a diagnosis? I've heard a variety of things including a bad fuel line and expired fuel pump. Any starting points would be greatly appreciated as well as any other possible diagnosis.

Thanks,
Andrew

[seaox230c]

your fuel tank vent is plugged-

[arupert33]

Crushing Fuel Bulb

Any pointers on how to go about repairing the issue? Is there a way to remove the external piece to make it easier or is it all interior?

[wilbur1]

Make sure the arrow on the bulb is pointing toward the engine.

[arupert33]

Crushing Fuel Bulb

The arrow is pointing in the right direction. I obsessively double and triple checked that.

[artdf175]

normally you would start at the fuel tank vent, however you took the fuel cap off so that would rule out the vent being plugged
as suggested first check the direction of the fuel bulb - there is an arrow on it to show the direction of fuel flow
there are a number of other things that would block the fuel flow
if you have a water/fuel filter between the tank and the bulb -it could be plugged
the fuel line from the tank could be bad. I had one that completely disintegrated on the inside, plugging the line and filters
there is a check valve on the fuel tank where the fuel line connects- it is an anti siphon type valve — this valve has been known to be a problem
If you have had dirty or old fuel, the pickup tube in the tank should have a filter on the bottom end that could be checked
Start from the fuel bulb and work back to the tank - there is a blockage there someplace -but rule out the direction on the fuel bulb first
post back and let us know what you discover
Art

[catacom225]

Hi Arupert, Those primers have small one way valves inside them and don't take much to block or restrict there flow, Inspect or replace

[arupert33]

How can I check the valves on the bulbs without having to cut them open? Thanks

[artdf175]

you can remove it from the fuel line
but really don’t think that is your problem
one other point is the fuel bulb should be vertical position with fuel input at the bottom

and make sure the fuel flow through the bulb is the right direction
art

[arupert33]

What do I need to be looking for when checking for a broken down fuel line? I had it off a couple months ago and was able to see through the length of fuel line.

Andrew

[artdf175]

depends on where it is
if it is bad between the tank and a fuel/water separator. you won’t see it because that filter will trap everything
what have you checked on the list of things suggested?

what happens when you try to pump the bulb?
take the output side off. add a piece of fuel line and try pumping some fuel into a container

[catacom225]

Easiest way would be to run it on a seperate spare tank and fuel line, A crushing fuel bulb is generally caused by a restriction down stream of the primer,

[Solarman]

First thing, stop running the motor. You don't need your problem getting sucked into the motor. Something between the bulb and bottom of the tank is blocked up.
Follow the fuel line all the way to the tank from the bulb.
Any fuel filters remove and inspect, or replace. If bad fuel in filter, you should empty and clean tank, otherwise you may go through many filters.

If everything is clear all the way to the tank, then you'll need to inspect the fitting at the top where hose connects to the tank, it might have a blocked anti-siphon valve in it. You can remove, or replace the valve if it is your problem, if not the problem, you'll have to pull the pickup assy out of the tank. If the tank was full of trash, or bad fuel, it could be clogged.

If your fuel lines are soft, from using ethynol fuel, the hose itself could be collapsing, those lines will also block any filters, and have to be replaced.

You should have an inline fuel filter on your boat if you have a built in tank. If not you should add one. And once you have fixed your problem, you should be running some fuel additive to help with these and future fuel problems. You never know what you get from some gas stations.

If you find black sooty specks from fuel in filter, your hoses are breaking down from ethynol fuel. If yellow - orange fuel from filter the ethynol fuel has phase changed from sitting and absorbing water too long.

Good luck, post back when able to let us know how it's going, and what you find
.