I have a 2001 3500 that I bought new and initialy had problems with the fuel rails which the dealer finally fixed and no problems untill recently. While cruising on the highway doing about 75-80 mph the service engine light comes on and I loose power and it wont go faster than 65 mph. I changed the fuel filter and put 2 stroke oil in the tank and it still does it. It never occurs while driving in the city and sometimes on the highway it will drive two hours or so before it happens. any ideas or suggestions? Anybody know of a good mechanic in Miami, FL That can help?

Thanks guys,
Lou.

if oyu are losing power 2 stroke oil isn't going to help, it sounds like maybe fuel pump problems or fpr is not suppling the correct amount of pressure

It sounds like fuel starvation. What is the code set? If it's vacuum draw too high, that means your fuel filter is clogged up.

Mine does that when it starts to gel up in the winter.....

jb

got an 01 that just started doing the same thing when the service engine soon light comes on it wont tack over 2000 rpm you can mash on it and it still has power then it hits about 2000 and just quits pulling put a new fuel filter on it it didnt help

Mine had the exact same issue, and it's at the dealer this very moment getting a new Fuel Pressure Regulator. It seems that the diagnosis is that the return valve located within the FPR is intermittenly getting stuck open and causing a portion of fuel to be sent back to the tank. A problem that only arrises when I mash quite spirited on the pedal. Driving miss daisy around town there is no problem.

just got my truck back last wed from dealer for exact same thing,was setting code p0093.only happened after about 70 miles of interstate speed,turned out that my injectors were bad,got new injectors and took it out and turned edje all the way up to 6 and ran the hell out of it,never happened again even drove 200 miles non stop at 85mph,its perfect,fuel mileage is even running 22.5 mpg on interstate

My story with P0093 was new injectors, fuel pressure regulator, fuel pressure sensor, tried shimming the fuel pressure relief valve, tried adding a lift pump, finally replaced the CP3 and that is what fixed the problem. Good luck!

so the dealer called last night and it turns out that it's not the FPR. i was pissed! this is now the 3rd part that they have replaced that has not fixed the problem. they said that now it was the CP3 and that they want $1500 for that work. I'm making them eat the $900 for the FPR, but they got me for $750 already for the fuel pressure sensor and the turbo overboost sensor. i didn't really call anyone names like "parts changer" or anything like that but i got pretty vocal about how they failed to properly diagnose the problem. i personally don't think it is the fuel pump itself like they are saying. i think they are guessing. i mean, if it were the CP3 then i should get low or no fuel pressure all the time. my problem is that when i accelerate the fuel pressure drops and the engine flattens out. it's fine driving around normal. about half a second after i initialize a spirited throttle action, the pressure drops. i think that 's some other faulty part or/and some of the fuel is getting returned to the tank. i'll let them buy me a new CP3 if that doesn't fix the problem.

Thanks for all the info, keep it coming. It sounds like you guys deal with first class parts changers like I do!

yeah, i just get depressed because it seemed like there was a time when every swingin dick that worked in a shop was good and can diagnose and repair instead of guessing with throwing parts at it, etc. i feel the same way about radio shack.

[quote=Lastplace;2857922]so the dealer called last night and it turns out that it's not the FPR. i was pissed! this is now the 3rd part that they have replaced that has not fixed the problem.

WOW :eek:... looks like you have to find another dealer...

My Truck ('01 GMC Crew Dually @ +/- 89,000miles) was doing the same thing, initially it would throw a P0093 code during pulling a trailer. Then it started doing it on the hi-way @ 70-80.

Took it to my dealer... they had it for 3 days for diagnostics. They finally said it was the return rates for the 4 injectors on the left bank! they were @ 34 ml. Normal 16?

Then they said the truck was 2 months out of the "Special Policy Warranty" and quoted $2,200 to replace the 4 or $4,200 for all 8! :mad:

So I went & talked to the manager, he reviewed the case with the GM Rep and decided it was possible to do it under the "SP".

Just changing parts until the problem is found is BS!!! not to mention costly.

Oh, I forgot to mention it helps to have a good name in the community ;).

Good Luck,

Raymond
Hover-Shuttle

well, that was the problem. CP3

got the truck back today to the tune of $1653. Runs good.

what is a cp3

it is the mechanical pump that pressurizes the fuel rails to the desired 23,000 psi, it sits down in the bowl of the engine between the heads dead center in the front, pita to get in and out but can be done by anyone that can turn a wrench, you have to take off most of the parts on the front of the engine to get to it, if you look at the duel fuelers for instance ppe or others they show a picture of the pump itself, same pump that is installed on the engine.
Hope that answers your question.

I agree with everyone else, mine went bad on my 02, was commanding 23,000 psi and at wide open throttle with a hot tune, would drop clear down to 13000 psi, the pump was the culprit.

I have a 01 3500 that runs great normal but as soon as I hook to my trailer and try to run it about 60 to 65 it will go in limp and set a p0093 code replaced the frp and pressure sensor and fuel filter but the filter the dealer sold me was white

My Truck started to do the exact same thing about a month ago. The parts changers say that it is the injectors but it never smokes. The code is a large fuel leak, but there is no fuel in the oil. Buddy thinks it is the CP3. I guess I will find out.

It is the cp3!

Buy a new one for $504 at gmpartsdirect.com.

You could get a used one with low mile car-part.com. 01-04

Sloppy, is there a specific parts description other that just cp3? And also does any one know where I can find a repair manual for the duramax?

Thanks Guys,
Lou.

Cp3 is the fuel injection pump.

Helms makes a good set of manuals.

http://www.helminc.com/helm/homepage.asp?r=http://search.msn.com/results.aspx?q=helms+manuals&form=QBRE3