Why the F___ is there air in my fuel filter!? - PeachParts Mercedes-Benz Forum

Austin85 · #1 11-28-2005, 10:10 PM

I am constantly loosing power and stalling out recently. BIG PITA.
The only reason I can see is there is always a big bubble of air in my primary fuel filter. Even pumping the primer fills it up, but then the fuel empties back and has an ar pocket in the filter again.

I have just tightened and checked all hoses under tank, and replaced and tightened all hoses under the hood.

Any ideas what else could be causing this air to get in my fuel system?
appreciate any takers,
AA

lietuviai · #2 11-28-2005, 10:21 PM

Are you running WVO? It's probably to thick now for your IP's fuel pump to pull that fuel. I had that problem so I added a small electric fuel pump at the WVO tank to help push the fuel along.
Problem solved in my case.

Astroman · #3 11-28-2005, 10:28 PM

Also check the rubber o-ring (if you have one) on the banjo bolt atop the fuel filter. If it is wasted you may continually build up air in the system rather than purge it. You'll have to pull it and check, should be about halfway down the shaft. But before that I would check the fuel screen in your tank. If it is plugged the pumps will pull so hard they will suck air from almost impossible places...

boneheaddoctor · #4 11-28-2005, 10:29 PM

Quote:

Originally Posted by Austin85

I am constantly loosing power and stalling out recently. BIG PITA.
The only reason I can see is there is always a big bubble of air in my primary fuel filter. Even pumping the primer fills it up, but then the fuel empties back and has an ar pocket in the filter again.

I have just tightened and checked all hoses under tank, and replaced and tightened all hoses under the hood.

Any ideas what else could be causing this air to get in my fuel system?
appreciate any takers,
AA

how big is the bubble? what percentage of the filter approximately? They all have a certains size bubble in them.

MTUpower · #5 11-28-2005, 10:30 PM

If you are getting air in the primary- ie the first small usually opaque filter, you might have air coming in from somewhere between the tank and the filter, or the tank screen may be really clogged. A small bubble is not a major problem. Have you changed the secondary fuel filter lately? Is the primary fairly clean? Did you put a bit of fuel on the rubber of the secondary when you tightened it? I'm hinting at other than air problems because there are other causes that seem more likely than a "air bubble" which would cause loss of power. How often does the problem occur?

Austin85 · #6 11-28-2005, 11:04 PM

Quote:

Originally Posted by lietuviai

Are you running WVO? It's probably to thick now for your IP's fuel pump to pull that fuel. I had that problem so I added a small electric fuel pump at the WVO tank to help push the fuel along.
Problem solved in my case.

I'm running WVO blended with 20% RUG to smoothit out. Plus I'm in So. Florida and it's above 70 degrees. But a fuel pump has been suggested by MattSD, so that may be in the cards anyway.

Austin85 · #7 11-28-2005, 11:06 PM

Quote:

Originally Posted by Astroman

Also check the rubber o-ring (if you have one) on the banjo bolt atop the fuel filter. If it is wasted you may continually build up air in the system rather than purge it. You'll have to pull it and check, should be about halfway down the shaft. But before that I would check the fuel screen in your tank. If it is plugged the pumps will pull so hard they will suck air from almost impossible places...

I pulled the screen filter and it is clean. The banjo bolt is the bolt that holds the spin on tight??? If so I will check for a washer/Oring. Never noticed one there.

Austin85 · #8 11-28-2005, 11:07 PM

Quote:

Originally Posted by boneheaddoctor

how big is the bubble? what percentage of the filter approximately? They all have a certains size bubble in them.

I put the filter horizontal and the bubble was almost 50% of the filter....

Austin85 · #9 11-28-2005, 11:10 PM

Quote:

Originally Posted by MTUpower

If you are getting air in the primary- ie the first small usually opaque filter, you might have air coming in from somewhere between the tank and the filter, or the tank screen may be really clogged. A small bubble is not a major problem. Have you changed the secondary fuel filter lately? Is the primary fairly clean? Did you put a bit of fuel on the rubber of the secondary when you tightened it? I'm hinting at other than air problems because there are other causes that seem more likely than a "air bubble" which would cause loss of power. How often does the problem occur?

Both the primary and secondary are clean, the spin on I changed yesterday. The tank screen is clean too. And I did put fuel around the seal.
This was happenning usually by the end of the day of driving each day for last week or so...like in the evenings....

Matt SD300 · #10 11-28-2005, 11:21 PM

Quote:

Originally Posted by lietuviai

Are you running WVO? It's probably to thick now for your IP's fuel pump to pull that fuel. I had that problem so I added a small electric fuel pump at the WVO tank to help push the fuel along.
Problem solved in my case.

Austin,

Have you installed the Fuel pump at the tank I told you about??????????

8500 miles on the benz & 6000 miles on the Cummins running RUG/WVO.......Both Car & Truck running GREAT?

The Truck is now beating up..ok more like pounding on the 300+hp Powerjokes & Duracracks "I turned up the fuel little more"

I also just installed pyro & boost gauges.

Elktonjohn · #11 11-28-2005, 11:24 PM

Questions, not just for my own benefit, really, but...are you heating the wvo, what type of oil is it...hydrogenated soy or what...how are you filtering it/washing it and how's that going for you so far? Seriously I'm asking because maybe the air in your primary filter is kinda typical...mine is usually like 75% fuel at idle... and you say you normally experience problems in the evenings like when it's cooler then during the day...wvo is not all that viscous, maybe un-heated vo at lower temps is harder to pull into the IP, less fuel, more air....dunno, just a thought...and since I'm gonna go veggie myself I am curious about your system's symptoms...

Austin85 · #12 11-28-2005, 11:33 PM

Quote:

Originally Posted by Elktonjohn

Questions, not just for my own benefit, really, but...are you heating the wvo, what type of oil is it...hydrogenated soy or what...how are you filtering it/washing it and how's that going for you so far? Seriously I'm asking because maybe the air in your primary filter is kinda typical...mine is usually like 75% fuel at idle... and you say you normally experience problems in the evenings like when it's cooler then during the day...wvo is not all that viscous, maybe un-heated vo at lower temps is harder to pull into the IP, less fuel, more air....dunno, just a thought...and since I'm gonna go veggie myself I am curious about your system's symptoms...

No heat.
It's veggie oil, non-Hyd.
4 micron gravity filter
when it runs it runs great