M1008 air in fuel line

[TedO]

If my trucks sits for a few days, in order to start it, I have to crank it, then open the plastic cap on the fuel filter to let the air bubbles out, crank, bleed, crank, bleed, crank, then it starts. It runs fine, unless I let it sit for a week. Is there a spot between the tank and injection pump where I should look for a leak?

 

[Barrman]

Inside the tank the fuel pick up could have rust holes. The hose from the pickup to the fuel pipe could leak in air. The hose between the pipe and the fuel pump could be the issue. The fuel pump could have a bad diaphragm. The metal pipe from the fuel pump to the passenger side valve cover could be bad, but since it is under pressure it normally isn’t the issue. The hose from the valve cover area to the fuel filter. The fuel filter base is a known source for letting air in the system.

 

[deank]

If none of the rubber fuel lines have ever been replaced, now is the time.

 

[TedO]

Inside the tank the fuel pick up could have rust holes. The hose from the pickup to the fuel pipe could leak in air. The hose between the pipe and the fuel pump could be the issue. The fuel pump could have a bad diaphragm. The metal pipe from the fuel pump to the passenger side valve cover could be bad, but since it is under pressure it normally isn’t the issue. The hose from the valve cover area to the fuel filter. The fuel filter base is a known source for letting air in the system.

Thanks. I have replaced all the lines recently. I am suspecting it is the fuel pump.

 

[nyoffroad]

Before I'd jump on the fuel pump, I'd be looking really hard at the filter assembly. I doubt the leak is big enough to see fuel dripping but you may find a damp spot, do you have a way to pressurize the fuel tank? Just a few (5psi) will show you where the leak is. If you can pressurize it and let it set for a half hour or so and watch, some clean dry cardboard under will help show where to look. My money is on the filter.

 

[owensexport]

Fuel Pressure Switch and Hard Starting CUCV

If your CUCV is hard starting in 60+ degree weather (and lower) you need to replace the fuel sensor switch located in the Stanadyne 80 fuel filter base. It is round with two wires and held in place with a round spring clipunder the filter. They crack with age and you may or may not see it...

www.steelsoldiers.com

 

[TedO]

Before I'd jump on the fuel pump, I'd be looking really hard at the filter assembly. I doubt the leak is big enough to see fuel dripping but you may find a damp spot, do you have a way to pressurize the fuel tank? Just a few (5psi) will show you where the leak is. If you can pressurize it and let it set for a half hour or so and watch, some clean dry cardboard under will help show where to look. My money is on the filter.

I was looking at the fuel pump more closely and I can see some fuel seepage.

 

[TedO]

I was looking at the fuel pump more closely and I can see some fuel seepage.

Also, I dont have the problem when the fuel tank is filled. The fuel level is higher than the fuel pump, so the fuel doesnt leak back to the tank.

 

[joefreesoil]

Don’t know if you got it fixed, but I experienced very much the same issue last year.

In my case, after going through filter and hoses, a replacement fuel pump took care of the hard starts and air in the return fuel line. Best of luck.