Engine/Transmission (1998.5 - 2002) Air in fuel. Where to look?

[Tinman]

The 01 has had an issue with hard starting due to air in fuel for sometime. It started about 10-12 months ago and only after sitting for many days with the front end pointed slight uphill. It's started to get more common and sometimes after sitting overnight. I've searched here and found everything from injectors to tank. It can't be the vp since it replaced it a few months age due to 0216. Didn't change a thing. It is very sporadic. Any suggestions as to where to start to look.

 

[Bob Cochran]

I think I would check all fuel connections you took loose when replacing the VP. I have found in most instances when you have a problem go to the last repair.

 

[Sticks]

Best way to find it is to pressurize the fuel tank to 10psi and start looking for drips.

Budget version is an air compressor, blow gun and a rag. Pressurize the tank for a couple of minuets then go look for the wet spots. Best to make sure everything Fuel lines and engine) is clean and dry.

 

[HBarlow]

How do you know you have air in fuel? Have you actually bled air out of the injector lines?

If true it would have to be caused by leak in a fuel line or a bad fuel transfer pump.

 

[JCyrbok]

common place on the 2nd gens for air to get in is the fuel line connection at the top of the fuel tank module. The elbow that the line connects to is metal and tends to rust out and get pin holes in it. That would be the first place I would check.



Hope this helps



J-

 

[FourBarR]

How about the check valve at the back of the head. Could be allowing fuel to drain back to tank. just a thought,hope you find it .

 

[Tinman]

Thanks for all the input.



The connection on the tank was my leading suspect. I have let the Fass run a few second after a failed start and I can hear the gushing in the pump. I figure it was air. One of the things I was wondering is if there is a problem of FASS's leaking internally.



I have check every where for wetness or sweating and there is no evidence of a leak anywhere.



Not familiar with the check valve at the back of the head.

 

[gtwitch]

strange but true!!!

Had a similar problem!! I finally found that the fuel line on My 99 where it runs between the tank and frame in the molded passage in the tank had filled up with fine dirt and that acted just like having sand paper or grit in there and it had abrated a long hole on the frame side of the line, allowing air to be pulled in to the line. I finally found this when a very slow drip was spotted on the ground below the tank area and was dripping from the frame. I couldn't find a replacement line so took the old line to the shop and very carefully siiver soldered it up and then put rubber protection around the line when I reinstalled the tank against the frame. By the way, I know that Dodge later had a fuel flow test for the lift pump. I can't remember what this test was, but it was a certain amount of fuel at the VP 44 for a given amount of time. Anyone remember this Spec???



gtwitch in Wyoming

 

[FourBarR]

Sorry i gave you a bum steer on the check valve, dont know what I was thinking about. Seems sometimes I cant seperate my thinking on airplane problems and cummins,getting old . The check valve I was thinking about is on the vp-44 return line to the tank. Its the front line the check valve is part of the banjo fitting, if you remove the bolt from the banjo you will find the check valve. Hope this helps with the problem all the best.

 

[Sticks]

Had a similar problem!! I finally found that the fuel line on My 99 where it runs between the tank and frame in the molded passage in the tank had filled up with fine dirt and that acted just like having sand paper or grit in there and it had abrated a long hole on the frame side of the line, allowing air to be pulled in to the line.

Not as uncommon as you think.

By the way, I know that Dodge later had a fuel flow test for the lift pump. I can't remember what this test was, but it was a certain amount of fuel at the VP 44 for a given amount of time. Anyone remember this Spec???



gtwitch in Wyoming

That test is a joke. I don't know who made it up or where they got their specs but it was not from Bosch. I have tested several trucks according to their specs that were throwing the P0216 code and had driveability issues (stuttering, white smoke, low power) that passed the DC fuel flow test. Replaced/upgraded the transfer pump and the P0216 code went away as well as the drivability issues.



From the mouth of Bosch - VP44 fuel requirements are 10 psi minimum (DC Specs said pressure was irrelevant - not true) and your volume is what ever the OEM fuel lines will provide at that 10 psi.

 

[Tinman]

I think the check valve was replaced with the VP but I'll make sure. I order a Dormer fitting from Glacier diesel and I am gonna replace the tank to FASS fittings first, then go from there.

 

[Batman]

While you are inspecting your fuel lines at the tank... ... you should also check your brake lines running beside the tank. If you haven't replaced them yet, they could be very rusty. I had to replace all of my lines this past summer
good luck