Air in fuel with video

[Twisted Steel Performance]

I have bubbles in the return line from the IP.

Everything is a year old, tank p/u, lines up to the Lp.

The bubbles ARE NOT showing up until the motor warms up, then they are always there until it sits over night.

I have disconnected the feed line at the Lp and connected a hose and dropped it in a jug of fuel.... and even then the bubbles were there...

Has anyone ever seen a injection pump cause bubbles...

here is a short video

 

[schiker]

Any wetness in the valley? I would think it would seep some fuel after shutdown if it was coming from an IP leak.?

Only guessing here...is there a front seal that can leak crankcase pressure into the IP then seep fuel into engine a small amount not noticeable . Maybe take off the oil cap and see if bubbles lessen????

 

[Quadstar Tuning LLC]

I never specifically checked with the clear hose but I suspected my last DS4 was doing this and cold starts were painful and smoky as a few lines had air in them until it worked it out. I had a few so I swapped a newer 5521 on and it's been perfect since

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[ak diesel driver]

Yes I've seen an IP do this. Didn't leak externally either.

 

[Will L.]

Suckfest. The clear fuel line ip test from gm manual is replace in and out lines for IP with clear. If yes bubbles in and bubbles out IP is defective and replace.

As for what actually casues it idk. Dealerships never get inside the ip other than sensors.

Ive always wondered what is the casue- ive swapped 6 or 7 IP from it.

Need a pump man for those answers.

 

[snarl95]

Try tightening the air bleed on the fuel filter. Mine came loose.

 

[Twisted Steel Performance]

Nothing leaks and no damp spots anywhere, dry & dusty...

The only thing that it does is idle up a little higher, no smoke, always starts easy ...

Guess the IP is causing it.....

 

[Twisted Steel Performance]

I think I will install a clear line on the inlet to the pump and see if the bubbles are flowing through the system... if not it's the pump....

 

[Will L.]

If so, talk to John @ unique and see if he might has suggestions.

 

[Twisted Steel Performance]

Well for info here, I changed the IP and it confirmed the IP was bad, there are 2 seals in the pump that will cause bubbles no mater if your fuel system is air tight...