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I've been losing prime below a quarter of a tank. So I rebuilt the filter head and it was all fine. I also installed a lift pump and put in a new fuel filter. The problem continues to happen, but only below a quarter of a tank. I can get it to run if i reprime the system and the low fuel light does not come on. I can go about 2.5 miles before it does it all over again. I dont have any fuel leaks because i would've found them by now. I get a p0087 and p1093. Both are low fuel rail pressure. I am at a loss. I haven't found any threads on this. Anybody have suggestions or experience with this problem. Do I need to rebuild the frpv or install a shim? Would the fprv effect my mileage, too? Because I am getting horrible mileage (14mpg).
 

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I am have had the same problem also but noe mine now does it if the truck sits for more then 8 hours or so without running and with or without low fuel. I actually got on here to see if i could find some insight into this problem. Let me know if you come up with anything and ill do the same.
 

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I had a prime loss and it was the high pressure fuel sensor in the valley. Rebuilt fuel filter housing and blah blah blah and finally fixed it after the damn thing blew out and shot fuel all over the place!
 

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I get a p0087 and p1093. Both are low fuel rail pressure. I am at a loss. I haven't found any threads on this. Anybody have suggestions or experience with this problem. Do I need to rebuild the frpv or install a shim? Would the fprv effect my mileage, too? Because I am getting horrible mileage (14mpg).
When my truck started to act up I thought it was lossing it's prime also. Each time I reprimed it it seems to be OK. So I rebuilt the fuel prime pump (o-ring kit). Then it ran fine for awhile. To make a looong story short it ended up being the FPRV. Do the bottle test, this will tell you if it is your FPRV. It's a simple test that takes about 10 minutes to set up.

I also had the same codes as you have. Do the bottle test!
 

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yeah try the bottle test.. i was pulling up the same codes and my truck went into limp mode. I bought the shim kit from the dmax store and my truck runs good now, not too sure if this is the problem but its a easy fix!
 

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look at the bleeder screw on top of filter housing they are plastic and if tightened to much they will crack mine did the exact same thing i bought a new bleeder screw and problem was solved
 

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^ mine just did the same thing
 

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Discussion Starter #9
sorry to sound like a noob but what is the bottle test and how do i do it?
 

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Just my own 2 cents worth. I had the same exact problem as you did for the last 3 months. This is what I did:
1. Replaced fuel filter housing (brand new housing) - No fix.

2. Replaced rubber fuel lines from housing to FICM - No fix.

3. Found could not attain and hold fuel pressure above 21k psi. Replaced fuel injection pump - could attain full fuel rail pressure but still loose prime over time and hard start. - No fix

4. Finally lifted the bed to find a SEVERELY rusted fuel tank sending unit. Replaced sending unit, fuel cooler, and lines to underneath front door.

FIXED!

Trucks starts on one revolution like it used to and has all kinds of power again.

Noticed your signature picture has snow in it - might be worth a peek at the sending unit....
 
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I had a prime loss and it was the high pressure fuel sensor in the valley. Rebuilt fuel filter housing and blah blah blah and finally fixed it after the damn thing blew out and shot fuel all over the place!
Whats is the actual name of the high fuel pressure sensor? I can not find it anywhere, the only thing that comes out is the fuel pressure sensor but I think that one goes on top of the fuel tank. Also where is the valley?
 

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I have 2004 Duramax Diesel that keeps loosing prime. sometimes it will start okay for several months with out a problem. It seems to be happening more often lately. It does not matter how much fuel I have in the tank. It usually stalls within a few seconds of starting. It also seems to be worst in hot weather like we have had the last few weeks. I have also noticed a little fuel leakage lately by the wire to the left of the primer pump. The bleed off valve appears to be okay no fuel leakage around it.
 

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That's a common seal fail leak area, that's the wires for your fuel heater, inside the filter base. The rebuild kit includes those two O-rings, or just replace the whole fuel filter base with new (more $$, but less labor and hassle of a rebuild).
 
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lereeves42 - loosing prime

Truck always starts okay but stalls after a few seconds and when I re prime it, it usually starts and runs fine. I have never had it stall after re-priming it and it continues to run fine until I shut it off. Sometimes it will be okay for a month or so and lately it has gotten worse. I replace the fuel filter which did not help my problem. I can't seem to find any leaks except the one noted above by the wire coming out of the top of the pump primer. I am not familiar with all the new electronics on the newer vehicles as I retired from working on them in the early 90's. I took it to a local shop that is supposed to be good on the Duramax diesel and they couldn't figure it out.
 

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You're losing prime...it's leaking off. When you start it and it dies, you're burning the small amount of fuel in the line aft of the filter, then you get to the air pocket and it dies. Sharp changes to ambient air temps can trigger the seal failure event (too hot, too cold). It won't get better, it'll continue in decline and get worse.

Before you try to start in the morning, check that primer button. It should be firm. If not, prime it up to firm and then start. It won't die at that point and you'll be gtg.

I took it to a local shop that is supposed to be good on the Duramax diesel and they couldn't figure it out.
Since the introduction of ULSD fuel (10 years ago), It's the most common fuel system failure item on a Dmax. So common it is, the price of the complete fuel filter head (including a new filter, heater, WIF sensor, and new wire harnesses) has dropped to roughly 25% of what it once was. (supply, demand, higher mfrg levels,.....ah, capitalism) :laugh:

If they don't know and couldn't figure it out, maybe a Fjord shop could do better? haha:
It's literally as simple as removing two hoses/clamps and two mounting bolts to replace....15 minutes? Easier than replacing just the fuel filter itself. If you replaced the fuel filter, you can do this.

A bit more time involved; if those two hoses attached to the filter base are the original shaped rubber lines, those too should be replaced using bulk 1/2" bio-fuel compatible fuel line. With age, they crack and deteriorate.
 

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The problem is usually the o-ring at the fuel heater connection, or the seals in the primer pump. These get hot from the engine heat in that part of the engine compartment, and do not seal- The fuel pulls negative pressure in the lines, as it tries to drain back into the fuel tank, so any small leak in the housing or hoses, and the lines will be empty of fuel. Usually resealing the filter housing and replacing the hoses will fix the problem. A new filter housing, or seals and hoses are available from many of the Forum Supporting vendors- see the list at the bottom of the Forum.
 

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I had a very small leak at the fuel heater wire connection that would cause me to have to prime the truck 1-2 times a month. Little epoxy around the wire/fitting fixed it.
 
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