Fuel Filter Follies

DurocShark · Post by **DurocShark** » Sat Nov 04, 2006 6:00 am

It's been, what, a week since I installed my new filter and pump?

Filter clogged Thursday while at lunch. I carry a spare now so it was just 10 minutes to swap it out, but I'm still irritated that they clog so fast.

This time I decided to cut it open and see just what, exactly, is clogging it.

My previous theory was that there were chunks of rubber clogging it. Now I'm not so sure. There were no chunks of anything at all in the filter. No rubber, no rust, nada.

The filter element itself showed darkening in one half (I'm supposing it's the bottom half that stays submerged). No rust coloring, just a general darkening.

I can't help but wonder if maybe the filter isn't being clogged? But why would changing the filter resolve the issue? If it was something in the tank moving around to block the outlet, wouldn't parking and shutting the bus off for 10 minutes serve the same purpose as replacing the filter? Yet that isn't the case. I've tried it.

The hoses have been replaced, though I'm going to try it again next time the filter craps out. I don't know what else to do.

The only other known issue with my fuel system is the fuel pressure regulator leaks vacuum so the vacuum line has been disconnected.

vdubyah73 · Post by **vdubyah73** » Sat Nov 04, 2006 6:52 am

Next time it craps out don't turn the key off quickly crawl under and determine if your pump is actually running.

Bill

DurocShark · Post by **DurocShark** » Sat Nov 04, 2006 7:03 am

vdubyah73 wrote:Next time it craps out don't turn the key off quickly crawl under and determine if your pump is actually running.

Bill

It is, I can hear it.

vdubyah73 · Post by **vdubyah73** » Sat Nov 04, 2006 7:08 am

How much gas in the tank or does it happen at any level?

Bill

DurocShark · Post by **DurocShark** » Sat Nov 04, 2006 8:49 am

vdubyah73 wrote:How much gas in the tank or does it happen at any level?

Bill

Doesn't seem to make a difference. Full, empty, halfway, etc.

Post by **Amskeptic** » Sat Nov 04, 2006 8:50 pm

You've got to replace the pressure regulator. It maintains an important minimum pressure in the fuel rail. Fuel can boil very easily with a warm engine and give you vapor locks. If it is stumbling when engine is cold, it is possible that the pump can't maintain pressure if the regulator is wide open to the tank return.
Colin

DurocShark · Post by **DurocShark** » Sat Nov 04, 2006 9:10 pm

Amskeptic wrote:You've got to replace the pressure regulator. It maintains an important minimum pressure in the fuel rail. Fuel can boil very easily with a warm engine and give you vapor locks. If it is stumbling when engine is cold, it is possible that the pump can't maintain pressure if the regulator is wide open to the tank return.
Colin

Hmm... Hadn't thought that maybe the fuel side of the regulator would be wonky as well. (Vacuum just helps reduce the pressure during decel.)

Off to find one!

Post by **Amskeptic** » Sat Nov 04, 2006 9:45 pm

DurocShark wrote:
Amskeptic wrote:You've got to replace the pressure regulator. It maintains an important minimum pressure in the fuel rail. Fuel can boil very easily with a warm engine and give you vapor locks. If it is stumbling when engine is cold, it is possible that the pump can't maintain pressure if the regulator is wide open to the tank return.
Colin
Hmm... Hadn't thought that maybe the fuel side of the regulator would be wonky as well. (Vacuum just helps reduce the pressure during decel.)

Off to find one!

It is a guess as far as your symptoms. But I await your results

Colin

spiffy · Post by **spiffy** » Sun Nov 05, 2006 7:37 pm

My offer still stands to send you my extra FPR. For yous, no clams.

DurocShark · Post by **DurocShark** » Sun Nov 05, 2006 8:19 pm

spiffy wrote:My offer still stands to send you my extra FPR. For yous, no clams.

YES! I forgot about that... PM coming.

Randy in Maine · Post by **Randy in Maine** » Mon Nov 06, 2006 4:32 am

My suggestion would be to invest in a fuel pressure gauge so that you can figure out which part of the FI system is the problem, not just replacing everything to see if that helps.

Test out the temp sesor II also.

DurocShark · Post by **DurocShark** » Mon Nov 06, 2006 6:24 am

Randy in Maine wrote:My suggestion would be to invest in a fuel pressure gauge so that you can figure out which part of the FI system is the problem, not just replacing everything to see if that helps.

Test out the temp sesor II also.

Someday...

I know the FPR needs replaced anyway, so I'm not just throwing parts at it.

The pump was bad. It made lots of noise but did no pumping. Filter replacement is resolving the issue for some reason, and it's easy, so until I've found the real problem I'll keep doing it.

I wonder. If it really is a vaporlock or something similar causing the problem, maybe just cracking the screw on the rail to release pressure would provide a temporary fix. I'm going to try it next time the symptoms appear.

Oh, and I've used two different TS2's and had the problem with both.

The symptoms happen whether the bus is warm or cold. Sometimes immediately after pulling away in the morning, sometimes after driving for a while.

Randy in Maine · Post by **Randy in Maine** » Mon Nov 06, 2006 9:26 am

I am late to this party you are having.

How do you know the FPR is bad? If you want to try my spare known good FPR I can priority mail it out to you. Send me a PM with yoru address if you want it. 3 days to get it there.

Put that volt ohm meter on the Temp Sensor II and tell us what it reads cold and watch it as it warms up and tell us what that number is. The VOM will not wear out the more you use it.

Did you recently re-seal the fuel tank? Was there a rust issue?

When the fuel pump is running it should feel cold to the touch as it is constantly pumping 1L of fuel every 30 seconds and that fuel is what cools the pump.

DurocShark · Post by **DurocShark** » Mon Nov 06, 2006 9:29 am

Randy in Maine wrote:I am late to this party you are having.

How do you know the FPR is bad? If you want to try my spare known good FPR I can priority mail it out to you. Send me a PM with yoru address if you want it. 3 days to get it there.

Put that volt ohm meter on the Temp Sensor II and tell us what it reads cold and watch it as it warms up and tell us what that number is. The VOM will not wear out the more you use it.

Did you recently re-seal the fuel tank? Was there a rust issue?

When the fuel pump is running it should feel cold to the touch as it is constantly pumping 1L of fuel every 30 seconds and that fuel is what cools the pump.

FPR has vacuum leaks. I do have one coming from Spiffy, thanks.

I forget off the top of my head what the readings on my two TS2's were, but one was within the specs listed on Richard's site, the other was way off.

No rust in the tank, no reseal. New pump is chilly, as it should be.

Randy in Maine · Post by **Randy in Maine** » Mon Nov 06, 2006 11:04 am

Install a new temp sensor II. You should always have a new spare in your tool box also. Less than $20.

Itinerant Air-Cooled

Itinerant Air-Cooled

Fuel Filter Follies

Fuel Filter Follies