On my dad's 2001 Duramax with Allison..............

Yesterday it developed the sudden problem of needing to pump (the fuel primer) every 15 or so minutes to keep it running. It is in the garage right now (literally) because we need that truck!

Just wonder what to expect. Though I don't know the configuration of a chevy diesel, I'd _guess_ the fuel pump in the tank is bad/going bad and the high pressure pump can siphon the fuel out of the filter to a point. Therefore requiring the pumping of the primer.

Any logic to this?
Sorry I don't have any more info.

Andy

There is no fuel pump in the tank. There is no lift pump at all.

Did you recently change the fuel filter? Perhaps you have a leak.

Other then that it could be injectors. One of the first sign of injectors going bad is hard starting.

No pump in the tank.....crap.
FF was changed 2-ish months ago.
As far as I know, it runs fine, except he needs to pump the primer every so often (15 minutes, which would be 15-ish miles).

Injector issues scare me. Way out of warranty, I'd guess. When one goes, do they all go? how much are they? Now that you mention it, it seems like it had to crank longer than normal to start, though it always did start and seemed to run fine after that..

Like I said though, its dad's truck, otherwise I'd know more details.
Thanks for the info.

Does he have over 200k miles on the truck if not there covered. dave

Right around 100K. Sweet, they're covered!
GM must be eatin' the big one on injectors, man.....

I still hope it is something simple though. We need to haul the tractor this weekend. =)

If you got to prime it to keep it running, I would think Low Pressure Pump.

Hi aeblank,

Had the same problem in the first 3500 miles with a LB7, when truck was new.
Go to the other site and look for my thread, that I posted about mid June, 2004
for the whole story.

dyindmax,

Couldn't find your post. Don't know if it was too old, or what... Only found one thread you started (VIN lookup). A few others you posted to, but nothing seemed to line up.

Can you post a quick summary/solution?

Low pressure fuel pump? Where is it?! Not in the tank, as I have been told. =)
I guessed there must be 2 pumps. I just assumed GM would keep putting it in the tank.

There's only one fuel pump on the Dmax, in the front center of the engine valley. It does contain 2 stages in the one unit, a gear-type low pressure pump that pulls the fuel by suction from the tank and a triple-plunger high pressure pump that pressurizes the fuel rails to 20,000 psig plus. The low pressure pump pulls vacuum on a long fuel line. The fuel line runs from the sending unit on top of the tank along the inside of the driver's side of the frame all the way to the engine compartment. There it comes up near the brake master cylinder and runs through the two Fuel Injection Control Modules (FICM) on each valve cover to cool the electronics before going to the filter head and then the pump. There are some disconnects where the line comes into the engine and between the FICMs (silver boxes on the valve covers with "do not pressure wash" decals) and hoses and clamps on the filter head and between it and the pump. These could all be an air leak source. The filter mounting, some bad filters and things like leaving the old center post gasket on the head when changing filters have caused air leaks in the past. I would suspect an air leak that is keeping the low pressure pump from maintaining prime and would look carefully for this sort of problem first. Good luck.

Hi aeblank,

Sorry I gave you the wrong date for my thread on the GM site,
It's still on page 30, and dated July 21, 2004.

It reads: "Bought a Duramax, bought the best rode 3750 kilometers and got towed the rest"

As others have stated there is no fuel pump in the tank.
My Silverado 3500 Cab& Chassis came factory equipped with two fuel tanks and there was a electric fuel transfer pump between the front and rear tank.
All this pump did was transfer fuel out of the rear tank and into the front tank as required.

I think the post by "idle chatter" is pretty close to hitting the nail on the head. Look for the air leaks at the fuel module or fuel block or possibly thru the injection pump shaft seal.

The best way I know to test for this is with a hand operated Vacumn pump and a clear plactic fuel line or sight glass connected to the bleeder port at the fuel filter, if air bubbles are present, move back to the fuel block and try the line coming from the fuel tank. if no air bubbles are present, block the tank port and try again on the other side of the fuel block. Eventually you will be able to isolate where the air is getting into the fuel system.

My research has shown that air in fuel has been occuring in the fuel block connection seals. Several mechanic friends who are GM Tecs have provided me with information that they have eliminated the air in fuel problem when they changed these seals.
Though I am a certified Heavy Duty mechanic, I have never attempted to troubleshoot my duramax air in fuel system problems.
Because of the dealer fraud involved, I elected to take GM and the dealer to court instead.

Ok, I know a little more now, dad is here (helping me with my garage!).

With no load on the truck, it doesn't seem to do it. The vacuum is 1-2lbs under no load (empty) no matter what the speed. Vacuum is measured via a quick disconnect in the front passengers side of the engine.

Under load, (5K pound trailer), the vacuum is 5lbs @ 60 mph, on acceleration it is up to 10-ish.

It threw code DTC P0093.

We checked the fuel temperature, and it was less than 250 F (per the error code sheet), it was actually more like 120 F.

The system was pressure tested by the dealer @25 psi from the filter to the pump and from the filter to the tank, and it tested OK, per the stealer (er, dealer).
The fuel filter casting and the water drain check valve were both tested and OK per the pressure test.

It will run at 25 forever. Try to go faster, and it boggs. The fuel filter was changed as soon as this problem showed up, to no benefit.

Any ideas guys? The truck wants to go on a week+ long trip (on Monday) a few hundred miles away. If we can't come up with something by then, the 5.3L gasser will have to do the job.. =(

Well, a little more info....

Drove the truck tonight. Seems to run fine for 30-ish minutes, then the 'service engine soon' light comes on. I assume that is when it throws the code mentioned above.

After it starts to bog under load, you can hold 65 for 15-ish miles by babying it. Tried pulling the fuel heater fuse (no fuel heater, no glow plugs, and no air heater---all on a 15A fuse too!). Did not help.

Basically, it runs out of fuel. If you idle it, it catches back up (fills the filter again). It seems we don't have the correct amount of vacuum (10 psi under hard acceleration, 5 or less under constant speed).

I have heard of issues with a seal in the low-pressure side of the fuel pump. Anybody have any experince? Other than that, it can only be an air leak (supposedly tested and passed by dealer) or a restriction (doesn't seem likely, but maybe a piece of crap got jammed in the line somewhere?).

Just trying to keep the dealer out of the truck and save $ while doing it.....

Anybody?

FYI the dealer has done the full diagnostics. Says it is the fuel pump (all $824 worth). Still waiting on seals, so we'll see.

With that much vacuum I would say you are plugged up and not pulling air in. With a stock or slightly modified engine with two filters you should not see over 10 inches HG of vacuum at WOT. There are some guys here with real world numbers. My figure came from a GM TSB. Later! Frank

Check fuel tank cap vent maybe pulling vacuum on fuel tank.

Thanks for the replies. We'll try out both.

Unfortunatly, the problem is still there. FINALLY got the truck back (over a week to get stupid seals). Used it for a week, then went to tow the boat. Started the same BS again. Again we used a different truck and left the 'good' one at home. Going back to the dealer Tuesday. Will have to try out those things first.

Our best guess is that the screen in the fuel tank is plugged. That or the vacuum would do it, I guess. Frustrating, to say the least.

There is no fuel pump in the tank. There is no lift pump at all.

Did you recently change the fuel filter? Perhaps you have a leak.

Other then that it could be injectors. One of the first sign of injectors going bad is hard starting.

Does it make sense to add a "lift pump" as mentioned in many of this forum and other forum's threads? I've also heard that if you have a "pre-OEM" fuel filter kit installed, that this extra filter places undue stress (significant extra workload) on the OEM fuel pump. :confused:

Does that sound likely? :help2:

If so, what brand of lift pump is the best and can it be installed in the fuel line between the "pre-OEM" fuel filter and the OEM filter?
:help:

I am new to this board but guess what?? My 2003 Duramax is in the shop here in South Florida for the same problem. The truck will not hold prime. It started out driving fine with out a tow but soon as weight was added the truck failed now the problem has gotten worse. The truck will not go 8 to 10 miles empty without losing prime. The truck has 35,800 miles. The truck has been in the shop for a month. Now the factory is envolved. They have replaced all 8 injectors, the fuel pump, a lot of fuel lines, filter. As of last friday the dealer says he is lost.

crap, that doesn't sound good.

'ours' is in the shop right now. Don't know the status, but they have another week and a half before we 'need' to use it again. Sucks pulling stuff with 1/2 the truck you're used to. Please post if you learn ANYTHING. I check this thread once in a while. I will do my best to do the same. We got the factory to go halvesies on the fuel pump replacement. Too bad it didn't fix it. The fuel cap trick didn't do it. We're at a loss, hopefully the dealer isn't.

Wer'e at 105,000 miles, so condsider yourself lucky (well, sort of).

edit:
BTW: I don't think a lift pump is required. In my case, it is a half-ass fix at best. In most cases, if it ain't broke........ The electric pump would be pushing against a 'brick wall' all the time. Unless it has a built in pressure regulator, you'd just burn it up, I would think.

Mine is still at the shop. Now at 45 days. The dealer still cannot solve this problem. The engine runs 20 to 30 minutes at idile and dies. Loses prime every time. All injectors replaced, Injector pump, ALL fuel lines, Fuel cap, computer, filter and housing. I would hate to know how much money they have in this repair which started out as just needing injectors.

Bob

Not liking this.......

Mine did the some of the same things. vacuum leak in the fuel pump and replaced head gaskets also.

Ours is getting new injectors, I guess. Pump has already been replaced.

Head gaskets? You must have had fuel in your oil, no?

WOW, as much work as they have put into it and still no fix. I would ask them for a new truck even up. Or see if they will put a whole new engine and tranny in so you can get your truck back. I would be PI$$ed if they had mine that long and couldn't fix it and couldn't tell me what is wrong.

Jeff

I am new to this board but guess what?? My 2003 Duramax is in the shop here in South Florida for the same problem. The truck will not hold prime. It started out driving fine with out a tow but soon as weight was added the truck failed now the problem has gotten worse. The truck will not go 8 to 10 miles empty without losing prime. The truck has 35,800 miles. The truck has been in the shop for a month. Now the factory is envolved. They have replaced all 8 injectors, the fuel pump, a lot of fuel lines, filter. As of last friday the dealer says he is lost.

Hope you get it figured out soon and get your truck back. The only "plus" I see here is 35,800 miles. Good luck.

Ours is fixed!!!!!!!!!!!!

Ended up that there was dirt in the injectors (and lines, and pump).
Not sure what happened there. I'm going to see if we still have the old fuel filter kicking around, but I doubt it. Dealer couldn't give any hints as to what the heck.

It isn't my truck, but I'm going to try to convince dad to run a prefilter. I sure would.

So, this last time around was injectors (which were covered) and a fuel line flush, which normally isn't covered, but my dealer managed to get it covered.

I'm heading up north with it tomorrow. Yipee.

Good luck to you Goldwing Bob. I'm with the other guys, after 4 months they owe you something. Start nice, escalate to a lawyer. My uncle did that with dodge (cummins). If you have the same problem 4 times in a year (I think) you qualify for the lemon law (in MI anyway). He got a new truck for $1500 (the depreciation of the original truck). Ha, his name is Bob and he used to have a Goldwing. Seriously.

There have been a few cases of the bottom of the OEM filter coming unglued. Check out these photos. Later! Frank

http://pg.photos.yahoo.com/ph/fnsblum2004/album?.dir=ae1b&.src=ph&store=&prodid=&.done=http%3a//pg.photos.yahoo.com/ph/fnsblum2004/my_photos

Good to know.
Any recourse on something like that?

another question......

can anyone explain how dirt in the injectors would cause the truck to run fine, but make it run out of fuel (then we'd turn it off, pump the fuel filter pump, and we'd be good for a while).

UPDATE::: Truck is still in the shop. They have put in three sets of injectors, two fuel pumps, more fuel lines. Also tryed running from a fuel can to eliminate the tank and guess what??? It still will not idle for more than fifteen minutes. Yes there is air in the system as they have hooked up clear lines and can see air bubbles. Now hear the kicker. I have a case number with GM. My customer service rep will not return my calls. The truck has been in the shop since memorial day weekend. Anyone have any sugestions? The hole thing started when the truck hit the injector failure codes. The current response from the dealer is "we are working on it. Be pateint" Dealer also admits having more than $11,000 invested in this repair as of now. Lemon law does not apply for me as I am over the miles.

Bob

Just another quick thought. Should I request a new engine??

Bob

I have a 01 duramax that did the exact same thing. Would not hold fuel preasure, could pump the preasure up manualy and it would run for a few seconds. Turned out to be a bad check valve in the fuel filter housing. Replaced it and its fine. All of this started when I go a bad tank of fuel in NC. The check engine light came on, and then the truck lost power and wouldn't go over 25 mph or so. Somehow the water in the fuel got passed the filter and ruined the injector pump. Dealer replaced injector pump and filter and the truck ran fine for a week. Thats when it wouldn't hold fuel preasure and the dealer found it to be the check valve. I figured the bad fuel caused all these problems. Truck has been great for about 50,000 miles since.

Darryl Cross

I will ask the dealer to check this out. I think he told me he replaced the whole filter housing with a new one. Thanks any advise is better than none.

Bob

What is with 'fuel getting by the filter'. It happened to us, and several others here. Are the OEM filters that crappy? Will a prefilter solve these issues?

Again, good luck Bob.

Had to give you guy's the update. My truck is fixed. 68 days in the shop. The factory tech found and solved the problem. The "power commander" or ECM was bad. Now I know what your thinking. Why did they not check that before? They did. They borrowed one from another truck but the mech did not change the information in it before starting the vehicle. Or so they say. Anyway GM customer service gave me a free three year "GM Gaurd Warranty" no deduct for my troubles. Check this out. The shops charge back to GM is over $13,000. I wonder if they will get paid.

Thanks for all the help

Bob

Awesome news! Enjoy the truck.

The warranty seems a bit weak to me, but so goes it.
I don't know the deal between the dealerships and the factory. All I know is that when I bring something in, like say for this injector thing. It comes back and the AC doesn't work right.... Guess who gets to pay for it? AC worked fine before they tore down the top of the engine, but doesn't matter.

Dealers always seem to get paid.

Now, go burn some rubber off those tyres!