Fuel Delivery issues

Colorado Ron · Post by **Colorado Ron** » Sat Feb 03, 2007 5:21 pm

Ok. I had to rebuild the fuel pump twice. Stopped pumping fuel again. I decided to mount a elec 24v pump on. Still no fuel. Blew the lines in both directions. I can hear bubbling in the tank. So whats the deal? The only way to get fuel is to close off gas cap and force air into the tank. As long as I pressurize the tank there is fuel. I tried a gas can and got fuel as well, so pump is working fine. Whats in the tank? Is there something in there that could be clogging somehow unless pressurized? HELP!

pcolette · Post by **pcolette** » Sat Feb 03, 2007 5:44 pm

I recently had a similar problem with mine. The engine would stumble or cut out like it was being starved for fuel when there was plenty in the tank. A careful look into the tank thru the filler revealed some sheets of paper, etc. in the tank. I had the tank dropped and drained thru the filler and we found a 3-4 page work order (in German) with a metal grommet asnd wire still attached. Quite a bit of other debris also. Don't know how long that was in there.

Might be worth a look. A very bright flashlight did the job for me. Hope this helps.

Paul

Jim LaGuardia · Post by **Jim LaGuardia** » Sat Feb 03, 2007 7:01 pm

You can look at the pickup inside the tank by pulling out the fuel sender.
This takes just a few minutes to do after pulling the 4 screws from the access plate. Once the sender is out, use a flashlight to inspect, look for red flakes of paint(tank coating) , Silicone sealer, or any other debris that can plug the pick-up

lindenengineering · Post by **lindenengineering** » Sat Feb 03, 2007 8:27 pm

Gentlemen.

Before contemplating exotic modifications to the stock fuel feed system make sure the suction system is IRON CLAD tight with no vaccum leaks.
If you have an Espar in the truck viz a viz "K" version, and other add on units make sure the feed lines to the pulse pump are not leaking air into the lines since they are interconnected.

Cracking however minor on the flex lines can and often are the source of leakage into the suction lines causing a loss of fuel feed efficiency and abrupt cutting out.

Don't be tempted to use 5/16" line from Napa, it will work in the short term and then harden up to recreate the vacuum leaks you once had. The correct size is 7 & 5 & 3 mm respectfully. Not a cheap item but available diectly from a Wurth Distributer or BMW/Volks/& Merz dealers.
Dennis
Linden Engineering Inc
Willis APU Dynamics/Webasto Agents

EvanH · Post by **EvanH** » Sun Feb 04, 2007 3:57 pm

Dennis,

I went the cheap way out with the fuel lines from the local auto parts place...BUT...I added EFI-grade clamps at every juncture. No vacuum leaks in five years.

Any rebuttals???

-Evan

todds112 · Post by **todds112** » Sun Feb 04, 2007 6:22 pm

Don't be tempted to use 5/16" line from Napa, it will work in the short term and then harden up to recreate the vacuum leaks you once had. The correct size is 7 & 5 & 3 mm respectfully. Not a cheap item but available diectly from a Wurth Distributer or BMW/Volks/& Merz dealers.

Totally lost me on this one. Why would the size matter in it "hardening" and cracking?

EvanH · Post by **EvanH** » Sun Feb 04, 2007 7:22 pm

When I got my truck, the fuel lines were a nice friction-fit. No clamps. While this may be great for sex, I'm not sure about fuel lines.

The easily obtainable USA lines are every so slightly larger in inside diameter. Brand new lines slide on to the fittings, but don't squeeze on the fittings very well. I'll leave the sex metaphor for your head, but over time as the replacement fuel line loses it's elasticity and possibly cracks with age, it is much more likely to lose the seal with the fitting than the smaller stock hose. Which is why I went with clamps on the oversized replacement hose.

-Evan

lindenengineering · Post by **lindenengineering** » Mon Feb 05, 2007 9:44 pm

Gents cracking of 30 year old fuel line can be expected on a Pinz. The area prone to such degredation is at the joint where the flex line is slipped onto the steel pipe stub off the fuel tank.

Equally the Espar heater supply system can allow reverse leakage into the main system(since they are teed together) on a K. Even the pump is not immune!

For info 3mm is the same as an 1/8th inch. Hence 1/4 fuel line is about 6mm, 5/16ths is a tad loose on a 7mm steel pipe. Yes it will clamp down with a worm drive clamp but it has a tendency to pinch the hose carcase, this over time causes air ingress as the hose hardens with age & heat.
If you need to clamp down a hose try to use the wrap around clamp from Glemo of Germany, These evenly clamp down the hose with no pinching.
Dennis
Ladies and Gentlemen, stop your engines.