Wouldn't start for me, air again?

[SparkandFire]

Yesterday I stopped at the store after driving home from work, after I came out and tried to start the truck, no go!

It's done this to me twice now!

I push in the schrader valve, pssst- only air comes out.

Unscrew the fuel filter, fuel goes all over the place. Just to be safe, I grab a new filter, fill it with ATF, crank on it (20 seconds, wait, 20 seconds... start!)

What am I missing? I've got all new return lines/caps/orings, replaced the olive seals on all the fittings... where else is the air comming from? I'm stumped!

 

[Jake S.]

Do you have a cap on the schrader valve? Usually anything after the lift pump(including the returns) is pressureized so should leak while running. But air is smaller than fuel so maybe not. Try eliminating the line from the fuel filter to the returns and drive it. See if that helps. That rules out the return system for leaks.

 

[SparkandFire]

I put a new cap on the schrader when I did the return lines a couple months ago. I've also replaced the fitting on the filter housing with one that doesn't have the return line barb..

It used to be that if it sat over the weekend, it wouldn't start. After i did the return lines everything was great, started after sitting, no problem. It's just every once in a while, when the engine is warmed up, it won't start, and all I get out of the scrader valve is air.

 

[Jake S.]

Well, having removed the line going from the filter to the returns creates a dilemma. Any air that is trapped at the top of the filter has to go through the ip. If your returns are not not leaking, I would hook it up again. I ran through that with my truck. I put a clear piece of hose from the filter to the returns to see if air was entering. With bad orings I could see bubbles traveling up the line after I shut down the motor. After I replaced the caps and orings, no more air bubbles. Anywho, does it start then die? Typically with an air problem, the motor starts, then the ip starves for fuel, then the motor dies. Is the ip dripping on the valley pan?

 

[FoMoCo]

I have had the same problem, it only happen once and I was running on the rear tank. I was able to switch to the front tank and no problems since. I think my problem and maybe ours, could be the "shower-head" in the fuel tank. I am not sure, but have heard that these shower-heads degrade and fall off. So, if your tank is not almost full, you start sucking air. I am no expert, and I have not dropped the rear tank to confirm. Just FYI

 

[SparkandFire]

Come to think of it... Both times this has happened, it's been on the front tank.

But... The tank was almost full yesterday.

 

[icanfixall]

What about the lift pump... Is it an electric or the oem manual??? About the "olives"... Did you use green or black olives..... Just kinnding... Did you replace the olive at the number 8 cylinder to intake area... This olive is located at the end of the fuel return line that comes off the top of the injection pump. Some trucks don't have this hard line and some do.. Its in that threeway brass fitting way back there... Very hard to reach.....

 

[SparkandFire]

What about the lift pump... Is it an electric or the oem manual??? About the "olives"... Did you use green or black olives..... Just kinnding... Did you replace the olive at the number 8 cylinder to intake area... This olive is located at the end of the fuel return line that comes off the top of the injection pump. Some trucks don't have this hard line and some do.. Its in that threeway brass fitting way back there... Very hard to reach.....

I've got a manual lift pump, not too old (but that doesn't mean it's any good!)

I like the green olives...

I did change the olives on the hard line between the IP top cover and the three way fitting in the back, and I've got the bruises on my chest still to prove it.

I am going to try and hook up my fancy fuel pressure gauge this weekend. What pressure am I looking for between the lift pump and the IP ?

 

[plywood]

Another couple common causes for air intrusion are the water drain fitting if you have on and where the fuel heater wire plugs on or anywhere else on the filter housing for that matter.

Look for wet spots, I guess that may be hard if it's all wet from changing the filter and such.