Now I'm stumped

[EMD_DRIVER]

My truck has been sitting since Friday, while I was working on the driveline. When I tried to start it this evening, I ended up draining my batteries.

It never occurred to me to see if there was air in the fuel lines, until I went out for round two. I had the batteries on charge for about an hour and wanted to see if it might start. I also had the block heater plugged in. I knew it wouldn't take too much on the block heater since the garage has been heated all day today.

After trying it one more time, I decided to see if there could be any air in the fuel system. There was all kinds of air!! Once I bled it off, the truck fired on the second crank!

So... I have an electric lift pump and new return lines.. I'm wondering if this has been my problem all along. Every once in a while, it would be kinda hard to start. I figured it was my WMO fuel mixture. Tonight, however, it was on my straight #2 tank.

With an electric lift pump, I should be able to see any fuel leaks... I found none.

My questions are:
1) where else could the air be coming from? (I triple checked my 2nd filter mod.)

2) How much pressure should the air or fuel have at the scrhader valve? (Could my return lines be blocked?)

3) Where could I find a decent check-valve that will fit the 3/8" fuel line I'm using? (I know the lift pump has one, this might be good for diagnostic purposes.)

 

[Shadetreemechanic]

1: maybe you have an intermittant small leak that just allows air into the system when it is cold and seals as soon as the motor gets warm. Probably where metal is shrinking during this cold weather.
2. 7 psi I believe.

3. I have exactly the check valve you need on the CO2 canister for my beer kegs. It is barbed on one end and threaded on the other. So maybe a brewing supply store.

 

[icanfixall]

If you look back near the drivers side firewall you will see the fitting that the return line ends at and changes to rubber line back to the tank. That multi port fitting has a square rubber "olive" in it just like the fuel line from filter to injection pump has. They do harden and leak air or fuel. Its really hard to get at or remove too. Sorry...

 

[MIDNIGHT RIDER]

McMaster-CARR can fix you up with any configuration of check-valve that you could want.

 

[Agnem]

I'd bet most air leaks never reveal themselves as fuel leaks.