A couple "air in fuel" questions...

MicroBruin · **Posted:** Thu Sep 17, 2015 12:12 pm

I was wondering...could a leaky injector that may be dribbling some fuel into the cylinder while the truck is sitting allows air into the fuel lines that supply the pump? Or, is this not possible?

Also, is it odd that I can have a decent amount of air in the fuel filter/lines after the truck has been sitting a couple of days...yet, if I pump the plunger several times without bleeding, the truck turns over and doesn't idle rough or stall? I would think that amount of air would cause a purging event of some sort.

Thanks for ideas... I'm trying to get to the bottom of this annoying air in fuel problem/rough starting problem. Just a little confused

Rixram · **Posted:** Thu Sep 17, 2015 12:23 pm

I'm getting some erratic air in fuel issues of late as well. I think I've tracked it down to the new fuel hose connection on the HPFP. Looks like a worm gear stripped out.

I'm curious to see what you find.

MicroBruin · **Posted:** Thu Sep 17, 2015 2:41 pm

I'm planning on replacing the supply line to the pump, since it has a little chafing from rubbing on the water in fuel sensor connector. If that doesn't solve, I'm tempted to buy another second gen fuel head for $130 and swap that in, since it's probably 8-9 years old and appears to have a reappearing film of diesel on it. The fuel filter is tight, and hoses are tight. I have noticed a little noise when the fuel pump is operating before starting...almost a buzzy sound....I don't remember hearing that before, and it seems maybe a little louder than it should be? I hope it's not the pump acting up...that doesn't sound cheap!

flash7210 · **Posted:** Thu Sep 17, 2015 3:01 pm

On mine, I cut out the supply line coupling back at the tank and replaced with regular fuel line and clamps.
And the inlet line to the filter was rubbing against a bracket, so I cut it out and replaced with regular fuel line and clamps.

I also have a lift pump, but its not back in the tank.
Its a Facet type mounted next to the fuel filter. And I put a clear glass pre-filter on its inlet so I can see if air bubbles come through and see the crud it captures.

pjigar · **Posted:** Thu Sep 17, 2015 5:10 pm

flash7210 wrote:

On mine, I cut out the supply line coupling back at the tank and replaced with regular fuel line and clamps.
And the inlet line to the filter was rubbing against a bracket, so I cut it out and replaced with regular fuel line and clamps.

I also have a lift pump, but its not back in the tank.
Its a Facet type mounted next to the fuel filter. And I put a clear glass pre-filter on its inlet so I can see if air bubbles come through and see the crud it captures.

Same for me: all lines replaced with new rubber lines and band clamps + in-tank fuel pump + 2 micron post filter.

Rixram · **Posted:** Thu Sep 17, 2015 6:25 pm

I found two different problems on my CRD.
the first was a kinked hose leading to the fuel filter.
the second was a broken warm gear leading to the high pressure fuel pump.

I just ffixed up both of these, & I am hoping that this takes care of the problem.

MicroBruin · **Posted:** Thu Sep 17, 2015 8:53 pm

The worm gear is found just before the high pressure pump? How much trouble and $$ was that to deal with? Thanks.

CATCRD · **Posted:** Thu Sep 17, 2015 11:22 pm

MicroBruin wrote:

I'm planning on replacing the supply line to the pump, since it has a little chafing from rubbing on the water in fuel sensor connector. If that doesn't solve, I'm tempted to buy another second gen fuel head for $130 and swap that in, since it's probably 8-9 years old and appears to have a reappearing film of diesel on it. The fuel filter is tight, and hoses are tight. I have noticed a little noise when the fuel pump is operating before starting...almost a buzzy sound....I don't remember hearing that before, and it seems maybe a little louder than it should be? I hope it's not the pump acting up...that doesn't sound cheap!

This "reappearing film of diesel" on the fuel head could be a major clue. On my first gen the bleed screw seat became galled and wouldn't seal, probably from repeated use. Took me a while to figure out why the rim of the filter was wet with fuel when it was good and tight because the seep went from the bleed screw around back where I never saw it. Try cranking down the bleed screw or better yet new filter head.

MicroBruin · **Posted:** Fri Sep 18, 2015 1:44 am

Well, I've got the second gen fuel head, but it's old. I wonder how tight I could crank the bleeder down before doing damage. :?:

Anyone familiar with the guts of those things?? Is there a washer or o-ring in there to damage??

95Z28A4 · **Joined:** Sun Mar 30, 2014 9:53 am **Posts:** 297

I attached a link below to a web page that shows the filter head partially disassembled. You can see a rubber gasket between the filter head and the heater puck.

http://liberty.eurekaboy.com/fuelfilter.htm

I purchased a 2nd gen fuel filter head in 7/2014. The priming pump failed in less than 1 year. I removed the heater puck from the 2nd gen filter head, installed it on my original first gen filter head and re-installed it on our CRD. The combination has been working OK for the past couple months. The next time I replace the fuel filter, I am replacing the entire filter head with a Racor unit. I have read on this site that the export models were factory fitted with Racor filter heads. I attached links below to Racor installations.

http://www.auerbach.ca/kj/racor/

http://liberty.eurekaboy.com/racor.htm

http://liberty.eurekaboy.com/fuelpressuregauge.htm

CATCRD · **Posted:** Fri Sep 18, 2015 11:18 pm

MicroBruin wrote:

Well, I've got the second gen fuel head, but it's old. I wonder how tight I could crank the bleeder down before doing damage. :?:

Anyone familiar with the guts of those things?? Is there a washer or o-ring in there to damage??

There is a tapered metal to metal seat. No o-ring. Try to snug it down a little more.

Rixram · **Posted:** Sun Sep 20, 2015 11:58 am

Rixram wrote:

I found two different problems on my CRD.
the first was a kinked hose leading to the fuel filter.
the second was a broken warm gear leading to the high pressure fuel pump.

I just ffixed up both of these, & I am hoping that this takes care of the problem.

Update: Nope.

A couple "air in fuel" questions...

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