Author Topic: air bubbles in fuel line (Read 7146 times)

Hammy · « **on:** August 19, 2005, 06:38:00 pm »

Hi everybody;

I have recently been getting air bubbles in the fuel line. So I decided to replace the fuel line from the sending unit to the main plastic line under the car. I reused the check-valve, and used all new gear clamps, and the verdict is the same. I don't see any leaks anywhere. If I pinch the return line off for a short period, the bubbles go away. I can't imagine the return line being the problem, and i'm starting to suspect the IP. What kind of fuel pressure does the IP generate?

Thanks for any advice, and hope everyone is enjoying their summer.

fatmobile · « **Reply #1 on:** August 20, 2005, 12:41:36 am »

Bubbles in the line between the filter and injection pump right? I'd guess the fuel filter is clogged.
A vacuum gauge on the fuel line will always let you know if the filter is clogged, before there is a problem.
Got an "OUT" bolt in the return line banjo right?
Squeezing the return line slows down flow and causes less fuel to be pulled through the filer so less vaccum and fewer bubbles. Having said that, you are lucky one of the little return lines between the injectors didn't pop off and give you a diesel shower when you did that.

Hammy · « **Reply #2 on:** August 20, 2005, 08:34:37 am »

I have been wondering about the filter also. It was changed out about 6 months ago, mind you that could be equal to about 50000 Kms, so it could be due. I would certainly change it out before condemning an IP. BTW, what kind of vacuum reading should I get from the IP.

Thanks for your input Fatmobile.

fatmobile · « **Reply #3 on:** August 20, 2005, 09:33:11 pm »

You're welcome.
It's normally zero.
At 2 in hg. I start to think about it, by 5 I've done something about it. That's for diesel.
On vegy it rises faster. I've let it get to 7 before I did something about it.
Hey, we have the same car. Yours a T-red 4 door?

Hammy · « **Reply #4 on:** August 21, 2005, 08:47:43 am »

Thanks again for the info, Fatmobile.
My Golf is a 2 door, although I often wish it was a 4 door, when I have to strap the kids in, or throw my hockey equipment in the back, it's a pain. I guess I'm just getting too old to want to climb in and out of the back seat. When I was a teenager, I never got in the back of the car, except for when I was with my girlfriend! Jeeze I miss those days.LOL!

Hammy · « **Reply #5 on:** August 21, 2005, 08:48:44 am »

I'm trying a new filter today. We'll see what happens.

rackley · « **Reply #6 on:** September 01, 2005, 01:06:35 pm »

Moon, I'm having fuel problems right now as well. What kind of vacuum do you need to pull in order to get fuel out? I seem to need about 5-7 inches of mercury (3-5psi) in order to get fuel coming through any my aux fuel pump keep sucking air bubbles instead. I pulled my water seperator and it seems fine. I pulled my fuel pickup and it seems fine. The only thing I've pinpointed that really can obstruct flow is the check valve, but it only takes about 0.5psi to crack (1in HG).

fatmobile · « **Reply #7 on:** September 01, 2005, 06:49:02 pm »

Gassers have an intank transfer pump.
I wonder if it would work with diesel ... to help push the fuel along.
... or I wonder how long it would work with diesel.

Hammy · « **Reply #8 on:** September 01, 2005, 07:28:01 pm »

Sorry I didn't get back right away. I changed out the fuel filter and all is well now. I put a vacuum gauge on it before changing the filter, and it was pulling 6 inches of mercury, with the new filter it was less than one inch.

Thanks for the help Fatmobile.