Hi there. I'm new to this forum as of yesterday and to diesel pickups.
I've recently purchased a 2001 2500 SLT 5.9 TD. When cruising at 80km/hour, my rpms jump up a bit but then drop right back down. Friend of mine was having a similar problem in a gas powered pickup and it turned out to be a fuel pump. Could this be my problem?
Fuel filter had already been replaced, checked for water in the fuel, there
is none. I've done a seach here but have been unable to find anything like it. It seems llike I have 2 pumps on my truck?
A lift pump and a fuel pump. How can I determine which pump is causing me grief. Any help would be greatly appreciated.
Thanks
/Guy

 

One of the first things to check, is codes. Cycle the key to the "on position only" dont start it. Just cycle the key three times, the third time just leave it at the on position. Now look at the odometer, it will read a PXXXX code or simular.


You probably need to monitor your fuel pressure from the LP.

What I would do, install a fuel pressure gauge, either at the inlet to the VP44 (that's were I put mine) or right off of the LP OUTLET port.

You never want to let the VP44 go dry. It that happens you just might be spending big bucks on a new VP44.

And your next question would probably be, which fuel pressure gauge? There's plenty out there. It took me a couple of months to find the one I wanted. Started with Danin electrical gauge, which was very nice. But the response from the sending unit was too slow for me. I sent that back and picked up the fuel pressure gauge with the isolator. That one is a bit of a pain. But is most responesive. "Responesive", meaning, when you first turn the key on, "wait to start" light comes on, which turns on the LP for about 2 seconds. The electric fuel gauged did not responed to this. Too where the fuel gauge with isolator does responed. Oh , I stayed with Danin/Optix. There gauges are the best looking in my opinon. You can purchase them from: Danin from Jegs, Glaicer Diesel, Geno's Garage, Extreme Diesel performance etc.....

Just some food for thought there.

Hope this helps a little.

 

Thanks very much for the reply. I'll give it a try. I'll probably be back for more help. Just curious, I managed to speak with the fellow I purchased the truck from, he had changed both pumps about 12000km ago. Is it common for these pumps needing to be replaced frequently?

/Guy

 

Since I got my truck last December, I had the lift pump go out 2 times so I put in a big line setup and a FASS type system to get the pump closer to the tank to help reduce the strain on it and since then, I haven't had a problem with it since. As for the injection pump, I have heard of people with 300,000+ miles on their trucks and have never had to replace them, but then I have heard of people having to replace them after 50,000 miles. The best thing that I have heard of to help with the injection pump is to add some 50:1 oil to each tank of fuel to help lubricate it and make sure that you always have good pressure and volume to it as well.

 

Glade to help.

Yes it is common for these pumps to go out unexpectedly. It took me two years to get out of that. The big fuel line kit, with fitting to match, 3/8s inch fuel line from my AUX pump mounted back by the tank to the LP on the egnine. I have not lost a LP or AUX pump since 2005. Just pure luck if luck has anything to do with it.

Stock engines are almost in the same boat. Lots of places/forums in here to read up on. That's were I started a few years back.

That's why its so importent to get the gauges installed, at least fuel pressure, exhuast gas temp and manifold pressure. Even if its a stock engine. It is always good to know whats going on inside that engine.


Glade to help.

 

I'm not very smart on these trucks, so I could be wrong but it doesn't sound like a fuel pump problem to me. Is the truck an auto or stick? Mine did that but it was my clutch/pressure plate were pretty much gone. Somebody that knows a lot more than me will chime in I'm sure, but it seems to me if the truck bogged down it could be fuel related.. a short increase in rpm's leads me to believe it's something else?... I would take the recommendation of gauges to heart though. Very very important to have. Especially the fuel gauge even on a stock truck. They can save you lots of money and misery.

 

Very first thing to do: Get a fuel pressue gauge, reading between the FF and VP44 IP. By monitoring your FP, you can save your VP44. Without FP, the VP44 will certainly fail over time. This is $1,000 replace.
Look at a Big line kit from Vulcan and also at an AirTex pump. Their are considerably less than a FASS set up. Lots of options there, so do some research.
The FP gauge is a MUST!

 

I'm back. Not having the skill set or equipment, truck was brought in to the dealer yesterday. According to their tests, both fuel pumps are fine. The problem is easily replicated when driving and they did actually make it happen when they went for a road test. Mechanic and shop foreman both suspect it's an APPS(?) sensor but were not 100% on it. Cost of sensor is somewhere near $700 so they did not want to even suggest it without knowing for sure. No error codes are being generated. Hope to have this fixed before long. Oh yeah, it's an automatic. (4sp)
Thanks
/Guy

 

Try an APPS reset.
This procedure has shown to help 24 valve ISB engines. It is basically teaching the fly by wire accelerator on these trucks to reread the position of the pedal and it's limits. Most complaints this will help with is poor acceleration, improper shifting, bucking in 5 and 6 speeds. Has been known to increase fuel mileage in some instances.

1. Set parking brake
2. Disconnect negative battery cables on both batteries
3. Turn ignition key to run(to drain any remaining capacitors)
4. Let truck sit for 30 minutes( this is the recommended minimum)
5. Return ignition to OFF position
6. Reconnect both batteries and secure, not a timed event
7. Turn key to run position(not start) and depress accelerator pedal slowly all the way to the floor
8. Allow pedal to return to top position slowly
9. Turn ignition switch OFF
10.Release parking brake

If that doesn't fix it do a search on here for TIMBOs fix for the APPS, its a fraction of the price.

 

Busboy, I did as you suggested, and it does appear as though the problem has gone away. Not sure for how long...
Thanks very much.
/Guy

 

I'm back. Problem is back. I'm trying to find TImbo's post but am having problems. Does anybody have his email so I can ping him an email off line.
Thanks
/Guy

 

Timbom1976@aol.com, 717-577-1464