CHRISCARGUY

On my way home on Tuesday, my CEL came on w/ the dreaded "reducing engine power" on the display. Kept downshifting until it got to 20mph then the engine just shut off. Coasted to a stop and called Onstar for a remote dx. They said I had 4 codes all relating to low fuel pressure. Got roadside to tow me to the dealership that I work at- I'm the body shop manager. They replaced a sensor to see if it would be a simple fix- no luck. Now they're waiting for the high pressure fuel pump to arrive and try that. They don't think its the low pressure pump in the tank b/c it idles fine. Only has problems w/ starvation once under load. I am PISSED. 13XXX MILES, barely 1 year old and this.

northvibe

iTrader: (1)

stage 1 kit?

CHRISCARGUY

No stage kit yet. Just bone stock. And I wasn't even thrashing the car at the time. I had gotten up to 55 or so and settling into a cruise when it happened.

army_greywolf

iTrader: (2)

It can happen bust the spring inside the pump certainly would cause this issue, as it wouldn't be able to get up to correct pressure.

That said, CHECK YOUR LOW SIDE FUEL PRESSURE, before you do the pump replacement, as if the pump wasn't the root cause, it will destroy an otherwise perfectly good HPFP. And be sure never to run this car out of gas. Supposedly there is a sensor to prevent you from actually running it out of gas where the car will be "out of fuel" electronically but not actually. Good luck

CHRISCARGUY

Well, they replaced the high pressure pump- not the issue. There is some type of fuel bypass to allow fuel to go back to the tank in case of too much pressure. At half or greater throttle, it is opening wide open, sending all fuel back to the tank and starving the motor. They now are ordering a new engine computer!

CHRISCARGUY

New computer installed and programmed. The tech took it out, no codes thrown and drove fine for him. I took it out a few minutes later and floored it. Would accelerate strong, but the fuel pressure went up to over 2000psi and then felt like it hit the rev limiter even though I was only at about 4k rpm. The fuel cutoff is coming on too early and they think it has too high of fuel pressure. This is the first LNF motor they've delt w/ other than oil changes. I hate being the guinea pig. I can't take it anywhere else b/c I work at the dealership. Any ideas on what they could check out?

HyperMuffin

Try a different dealership?

army_greywolf

iTrader: (2)

I'll check into this tomorrow, the pressure is supposed to be regulated electronically, if it's reaching 2000 psi that's normal. The obvious things to look at are your fuel trims when your hitting that imaginary ceiling, it sounds like boost leak more than anything else. The motor trims out to a certain percentage beyond that it will set a code and reduce your power.

CHRISCARGUY

I'm the body shop manager at the dealership and if I just brought a tow truck in and had it moved to a competitor, they would NOT be happy. Grey Wolf, thanks for looking into this. I was thinking electronics as well. The master tech was on the phone on a conference call w/ 4 GM reps bouncing ideas. Now they have ordered all 4 fuel injectors and they won't be put in until Monday.

They thought they fixed it after the computer, but now at WOT it feels like it hits the fuel cutoff such as it would at the rev limiter, but at 3-4k rpm instead. They say they have the computer programmed correctly. If it's too much fuel causing a by-pass, its not a clogged injector b/c that would limit the pressure. Am I wrong here?

CHRISCARGUY

UPDATE: The tech got the fuel rail off and noticed gunk in the rail and in the new high pressure pump they just put in 2 weeks ago. It had only been driven about 2 miles since that pump was installed. At first he was going to pass it off as bad gas, but he finally dropped the gas tank and pulled the low pressure pump. The low pump has a filter and that filter was disintegrating and bits were being sucked into the pump! He took the pump and shook it upside down and black flecks resembing the filter material fell out! The gas was perfectly clean in the tank. So this **** was sucked throughout the fuel system and clogged the high pump, fuel rail, injectors, etc. Now they are replacing the low pump, high pump, a valve, fuel rail, and all injectors. They are flushing the bigger lines. And there are only 3 low pressure pumps in the US right now for sale. So maybe light at the end of the tunnel, if parts ever show.

umrdyldo

iTrader: (1)

That's depressing for the rest of us.

Josh Leverington

I have the same issue. GM had my car for a week couldnt find the issue. Car is in my car-port with a tarp over it.

ronn

iTrader: (3)

Found this discussion:

why no in-line fuel filter? - Chevy HHR Network

GM has stopped putting inline filters in some models since 2004. Other manufacturers have been doing it longer. The fuel sender assembly (pump/regualtor/sock/level sensor) inside the tank has a container on the bottom of it about the size of 1/2 coffee can. All the fuel pick up components are inside of this container. It has a small intake port in the very bottom that filters the bigger debris so that the fuel that is filling the container is fairly clean. The fuel fills the container and a sock(filter) is used at the end of the fuel pumps pick-up tube. Smaller debris that makes it to the sock is then filtered by the sock before entering the fuel pump and simply falls to the bottom of the container.

Todays pumps are much more robust then pumps of old also. We still see more failures of the old style pumps with inline fuel filters then we do of the newer style.

GM calls this a self cleaning system. Any debris that does not go into the canister of the fuel pump assembly falls to the bottom of the tank and any debris that the sock stops falls to the bottom of the canister when the fuel pump is shut off. We are talking very small amounts of debris here too.



all the more reason NOT to run your tank too low on fuel.
1)the in-tank fuel acts as a cooler for the electric pump
2)the debris will be "at the bottom of the tank", so the pick-up wont be!


Not sure if that applies to your situation though, since you say the FILTER desintegrated?
Have you ever run the tank real low..several times? Is there any chance you got gas that was contaminated with something?


Do you fuel up in a rural area where gas might have been contaminated?
Any additives?

On *Out of the way* gas stations:
You can definitely get "bad" gas, although what "bad" means can differ. There was an independent gas station in my small hometown that eventually got shut down for not taking care of their tanks--they were infamous for years before that for selling gas that would mess up your car.

As I understand it, newer regulations and requirements make it a lot harder for stations to sell gas with _sediment_ in it, or at least, if they do it nowadays, they're committing a much worse infraction. Used to be you would get a small fine, but now you could get driven out of business quickly, so it's less of a risk.

ronn

iTrader: (3)

I found this pic from the Duramax Diesel, but I think it's the same, since it uses High Pressure pump along with unit in the trunk. You can see the filter (*sock*) attatched:

Inform the customer about not using fuel additives, except for manufacturer-recommended products, such as ACDelco Fuel System Treatment Plus. Remember that any additive that is put into the fuel tank, such as to clean the fuel injectors, must first go through the fuel pump.

Corrosion and Contamination

The sulfur contaminants found in some of today's gasoline can have corrosive effects on the fuel system sending unit, disrupting electrical continuity and leading to erratic or false fuel gauge readings
.
ACDelco Fuel System Treatment Plus -- 20 ounce bottle part number 10-3003 (88861013); 12 ounce bottle part number 10-3004 (88861262) -- has a filmer additive that, when used regularly, helps protect the sending unit by cleaning sulfur corrosion and coating the metallic surfaces of the fuel system. It's recommended to use ACDelco Fuel System Treatment Plus at each oil change.

CHRISCARGUY

That looks very close! The issue is now fixed and running like a top. The "sock" filter in the bottom of the in-tank pump was the culprit. But you cannot see this filter w/o taking the pump apart b/c it is inside the assembly. I do run my tank down sometimes until the "low fuel" indicator comes on--- I WILL NEVER GO BELOW 1/3 TANK EVER AGAIN! I had no idea that we do not have an inline filter. I'm going to print this and give it to the service dept because there will be a LOT of direct injected models coming.

ronn

iTrader: (3)

Glad to hear it. Ya never answered my question though....
aside from running the tank low..did ya ever use an *out of the way* station (contaminated tank at station). Have you used a lot of an *additive*..if so, which one?
I don't think the filter disintegrated.. **** getting into your tank would be my best guess here.

army_greywolf

iTrader: (2)

To the OP, good that the tech opened up the rail and had a look. Because of injector design they will require replacement once they've been contaminated, that or you will chase the problem until you finally break down to change them. I honestly had no idea there was no in line filter, but for some reason as many times as I've been under the car I thought I saw one...it's bugging me now.

FRSTGRDEDROPOUT

What kind of gas were you using?

08SSTCRD

Doesn't anyone diagnose anything anymore??

I would never order a high pressure pump for a car unless I was 99% sure it was the problem. GM is paying for all these guesses, and the dealership is probably going to get a nasty chargeback.

CHRISCARGUY

No out-of-the-way gas stations- all my regulars. In fact, most of the time it's the one right across from the dealership-the same one 3 different dealerships use. No additives added ever.

" Doesn't anyone diagnose anything anymore??

I would never order a high pressure pump for a car unless I was 99% sure it was the problem. GM is paying for all these guesses, and the dealership is probably going to get a nasty chargeback. "

No chargebacks here. The tech was on the phone a few hours a couple times w/ GM's help line and had all auth'd before doing any work. That is one reason why it took so long to repair.