Air in Fuel Filter: A Modest Proposal

Wobbly · **Posted:** Sun May 18, 2008 2:53 pm

This might not work for the CRD, but it did for my BMW 324TD: The BMW524TD, 324TD, and Vixen 21TD came with a fuel filter head similar to the Liberty's, that is, with a manual priming pump. They also had no lift pump, relying on the low pressure pump inside the Bosch VE injection pump to get fuel from the tank to the high pressure pump. All these vehicles had air in fuel problems, mainly due to air leaking in through the primer pump plunger shaft. BMW's solution was a filter head without a primer pump, and an electric fuel pump. In my 324TD and Vixen 21TD I installed a $25 NAPA electric pump between the tank and the injection pump, wired to the ignition. This solved the air in fuel problem.

Isn't the real problem that air accumulating in the fuel filter breaks the suction to the tank? I've read that air in the fuel doesn't cause cavitation to the CRD pump.

I plan to test this, but have too many other things going on right now.

Wobbly

Sir Sam · **Posted:** Sun May 18, 2008 4:04 pm

Wobbly wrote:

This might not work for the CRD, but it did for my BMW 324TD: The BMW524TD, 324TD, and Vixen 21TD came with a fuel filter head similar to the Liberty's, that is, with a manual priming pump. They also had no lift pump, relying on the low pressure pump inside the Bosch VE injection pump to get fuel from the tank to the high pressure pump. All these vehicles had air in fuel problems, mainly due to air leaking in through the primer pump plunger shaft. BMW's solution was a filter head without a primer pump, and an electric fuel pump. In my 324TD and Vixen 21TD I installed a $25 NAPA electric pump between the tank and the injection pump, wired to the ignition. This solved the air in fuel problem.

Isn't the real problem that air accumulating in the fuel filter breaks the suction to the tank? I've read that air in the fuel doesn't cause cavitation to the CRD pump.

I plan to test this, but have too many other things going on right now.

Wobbly

Wow what a great idea! lets install an electric lift pump! Dang, someone should hop on this idea pronto!

Joe Romas · **Posted:** Sun May 18, 2008 4:38 pm

Now Now Sam :lol:

It's 10 PM and my lift pump is resting in the tank

Wobbly

The CRDs's already have a relay, fuse and most of the wiring for a lift pump and it's even controled correctly by the ECM so 25 seconds after it's turned on and not started the pump shuts off :wink:

And the lift pump from Dodge that's for the Cummins powered trucks fits in and with a minor modification the fuel guage even works correctly

I used the NAPA pump and it worked but my cummins pump is a cleaner installation and it can be had on line for $150.

msilbernagel · **Posted:** Sun May 18, 2008 4:38 pm

That creaking sound is caused by the lengthening of your leg as it's being pulled by Sir Sam...

There's more than one thread that's been active recently having to do with either adding an external fuel pump, or replacing the unit in the fuel tank with one from the Dodge Ram pickups w/Cummins engines. They're nearly identical, except that the unit for the cummins engine has a pump whereas the CRD version does not.

So - good news, you're dead on.

The rest of the story - you've got some catch-up reading to do!

BTW - I live up around Battle Ground.

Mark

UFO · **Posted:** Sun May 18, 2008 4:43 pm

No need to get rid of the hand primer in the filter head. It comes in handy when replacing a filter element.

warp2diesel · **Posted:** Sun May 18, 2008 4:49 pm

....don't starve your CRD. I have used the same electric fuel pump trick on Volvo and VW Diesels with Bosch VE pumps. The VE pump had/has a chronic problem with input shaft seals sucking air and running like crap. I have yet to put one on my wife's TDI.

Steve

Wobbly · **Posted:** Sun May 18, 2008 5:52 pm

The thrust of my post was to install a cheap generic inline electric fuel pump-not a Mopar lift pump. A lift pump is certainly one solution, but it may be overkill.
With an inline pump mounted between the tank and the filter there's no need for the primer pump when changing a filter. There's no need to mess with the tank level sender, either.

Wobbly

Joe Romas · **Posted:** Sun May 18, 2008 6:12 pm

Wobbly wrote:

The thrust of my post was to install a cheap generic inline electric fuel pump-not a Mopar lift pump. A lift pump is certainly one solution, but it may be overkill.
With an inline pump mounted between the tank and the filter there's no need for the primer pump when changing a filter. There's no need to mess with the tank level sender, either.

Wobbly

But there are a couple of things that you must keep in find. One is if it fails it needs to be non restrictive and second it must pump enough fuel volume. Someone here determined after contacting Facet (sp?) that the pump that some of us were using didn't have enough volume (NAPA's specs were wrong) and when it was working it was actually starving the CP3 pump :cry:

Since the Dodge/Cummins uses the same CP3 pump their lift pump is a natural. I think another brand of external lift pump is Kennedy but as I understand they are not cheap :cry:

in my mind the health of my CP3 does not warrant being cheap.

The VE pump shaft seal is replacable and I've done a few of them. As long as the shaft and or housing is not worn that's all that's needed. I only needed an aux pump on one of my VW's and it's odometer broke at 250k miles.

Joe

warp2diesel · **Posted:** Sun May 18, 2008 6:31 pm

I used to have a bag of the shaft seals in my Tool Box and lost count long ago how many I have replaced. Most of the time, that was all that was needed. But like every thing else, there is always the turkey that burns you and you pull out all stops. Unlike our CP3 the VE was designed to self prime and handle a small amount of air. On our CP3 air seams to just hang in the dead spots and come in a big rush when you need power the most and cause the engine to stumble or stall. The lift pump solves the problem.

Steve

Wobbly · **Posted:** Sun May 18, 2008 7:30 pm

Joe Romas wrote:

Wobbly wrote:

The thrust of my post was to install a cheap generic inline electric fuel pump-not a Mopar lift pump. A lift pump is certainly one solution, but it may be overkill.
With an inline pump mounted between the tank and the filter there's no need for the primer pump when changing a filter. There's no need to mess with the tank level sender, either.

Wobbly

But there are a couple of things that you must keep in find. One is if it fails it needs to be non restrictive and second it must pump enough fuel volume. Someone here determined after contacting Facet (sp?) that the pump that some of us were using didn't have enough volume (NAPA's specs were wrong) and when it was working it was actually starving the CP3 pump :cry:

Since the Dodge/Cummins uses the same CP3 pump their lift pump is a natural. I think another brand of external lift pump is Kennedy but as I understand they are not cheap :cry:

in my mind the health of my CP3 does not warrant being cheap.

The VE pump shaft seal is replacable and I've done a few of them. As long as the shaft and or housing is not worn that's all that's needed. I only needed an aux pump on one of my VW's and it's odometer broke at 250k miles.

Joe

Good points. Is the Mopar lift pump non-restrictive, though? For a WAG of the pump volume required:
http://www.turbocompressori.net/common_ ... OR%20TANKS
mentions 0.5 l/min. Some of the cheap universal inline pumps flow 30 gph, or about 1.9 l/min.

Wobbly

Wobbly · **Posted:** Sun May 18, 2008 8:06 pm

Wobbly wrote:

Joe Romas wrote:

Wobbly wrote:

The thrust of my post was to install a cheap generic inline electric fuel pump-not a Mopar lift pump. A lift pump is certainly one solution, but it may be overkill.
With an inline pump mounted between the tank and the filter there's no need for the primer pump when changing a filter. There's no need to mess with the tank level sender, either.

Wobbly

But there are a couple of things that you must keep in find. One is if it fails it needs to be non restrictive and second it must pump enough fuel volume. Someone here determined after contacting Facet (sp?) that the pump that some of us were using didn't have enough volume (NAPA's specs were wrong) and when it was working it was actually starving the CP3 pump :cry:

Since the Dodge/Cummins uses the same CP3 pump their lift pump is a natural. I think another brand of external lift pump is Kennedy but as I understand they are not cheap :cry:

in my mind the health of my CP3 does not warrant being cheap.

The VE pump shaft seal is replacable and I've done a few of them. As long as the shaft and or housing is not worn that's all that's needed. I only needed an aux pump on one of my VW's and it's odometer broke at 250k miles.

Joe

Good points. Is the Mopar lift pump non-restrictive, though? For a WAG of the pump volume required:
http://www.turbocompressori.net/common_ ... OR%20TANKS
mentions 0.5 l/min. Some of the cheap universal inline pumps flow 30 gph, or about 1.9 l/min.

Wobbly

http://www.dieselplace.com/forum/showth ... p?t=187222 gives the spec for the Mopar lift pump and says that it's non-restrictive.

CATCRD · **Posted:** Mon May 19, 2008 12:39 am

Joe Romas wrote:

Someone here determined after contacting Facet (sp?) that the pump that some of us were using didn't have enough volume (NAPA's specs were wrong) and when it was working it was actually starving the CP3 pump :cry:

Joe

I did not hear about this. Details or links please.

Joe Romas · **Posted:** Mon May 19, 2008 7:48 am

CATCRD wrote:

Joe Romas wrote:

Someone here determined after contacting Facet (sp?) that the pump that some of us were using didn't have enough volume (NAPA's specs were wrong) and when it was working it was actually starving the CP3 pump :cry:

Joe

I did not hear about this. Details or links please.

EDIT: I found it :!:

http://www.lostjeeps.com/forum/phpBB3/vie ... 019#270562

UFO · **Posted:** Mon May 19, 2008 11:17 am

I have a Facet pump I am planning to install. It does not have a valve preventing fuel flow if the pump fails.

Air in Fuel Filter: A Modest Proposal

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