Engine/Transmission (1998.5 - 2002) Looking for opinions on erratic lift pump pressures I'm seeing.

[Coalsmoke]

Hey guys, I'd appreciate some thoughts from some of you who have had lift pump issues in the past. I bought my latest truck, the 01. 5 a few months back (said I'd never own a vp-44 truck but look how well that went ). There is evidence that the injection pump has been replaced by a previous owner and it has an Edge Juice with Attitude with a fuel pressure gauge on the input of the vp-44. The lift pump is in the stock position and appears to not be an upgraded aftermarket type.



Over the last few months the fuel pressure has been reliably 14-16psi at idle, and 10-12psi when driving. A few days back I changed the fuel filter, cleaned out the filter canister, etc and bled the air from the system, put 150kms on it and everything was good for a day or two. Yesterday, I noticed a very slight stumble, and driving around the fuel gauge was bouncing around the 7psi range. Today I'm seeing 20-21 psi, up until now I've never seen these extremes. I know that 5psi is considered the minimum safe vp-44 threshold, but for those of you that have been down this road before, would you suspect the lift pump may be on its last legs? Not a lot of spare money these days, but I'm thinking of maybe biting the bullet and buying the FASS HPFP kit before I have to head into a mountain trip planned for next week. I don't have the money for the dual filter FASS setups. Thoughts or suggestions?

 

[GHerrmann]

About 5 years ago my oem pump went south and had it replaced with another stocker. It lasted about a 1. 5 years then it took a crap. Had another put in, it lasted 1 month and was still under warr. I bit the bullet and put in a Fass95 and have had no problems since, been about 2. 5 years now and no problems. I say go for an aftermarket cause another oem won't last.

 

[rjrkihap]

Coalsmoke,

If the LP is in the original possition, chances are it's a Carter pump and therefore would not be capable of 20-21psi. My guess (assuming you have an electric gauge) is that you have a loose ground wire on the sending unit (as a missing ground wire will cause the gauge to peg at the maximum level). I would suggest you check your wires and continue to watch the gauge. Also, a FASS HPFP when your current pump fails.

Good Luck.

Ron

 

[Curious Dave]

Another FASS customer up and coming.



Don't be bashful... Go with the FASS and do it right. You won't be disappinted and the relief on your mind alone will be worth the money.

 

[Coalsmoke]

I took a better look at the lift pump, looks like a stock unit, and was hitting 21psi again last night. It could be a bad fuel pressure sender, but its not really acting like one. The sender is part of the Edge system and doesn't have a separate ground wire, it all goes back into the Edge unit and is a sealed harness. I'm thinking like Dave says to go with the FASS and just do it right. Just wanted to make sure I was chasing the right bird here.

 

[dresslered]

"... but for those of you that have been down this road before, would you suspect the lift pump may be on its last legs?"

Coalsmoke, first I have to ask about your fuel pressure gauge--electric or mechanical? Unless an electrical sender is properly 'snubbed', the input to the injection pump is a very harsh environment due to the injection pulses (creates kind of a water hammer effect). With this exception, I would bet almost anything that it is your lift pump going bad. I am on my 5th lift pump now, and only the very first one died a slow death (pressure gradually dropped to the 5-psi level). All the others experienced huge fluctuations in pressure from time to time which I believe is due to a sticking vane. Usually this would occur when the engine (fuel) was cold and it would go away after driving for awhile. However, I've also seen it start fluctuating in the middle of my drive for no apparent reason. Almost every time I suspected the fuel pressure sender was going bad, but the problem was always rectified with a new lift pump. My latest lift pump (Carter has gone thru many revisions) has been the mother-of-all pumps. I have seen nearly 15-psi at idle for over 40k-miles. It has slowly lossed a few psi off the idle, but still performing stronger than any other I've had before. Every time I replace one, I always think that I will relocate next time but have never gotten around to it. I'm sticking with the OEM for now as I still have several spares under the seat and the other pumps have had their share of problems and unique parts. Good luck.

 

[Coalsmoke]

Thanks Dresslered, its an electronic sender, don't know if its snubbed or not, is an air pocket the accepted method? It seems to work in a logical manner. Hearing your experience makes me think that a this one is going out the same way. When I've been hitting 20-21 psi it has been at low throttle applications or when just coming off of heavy throttle. I have 1000km round trip in a few days so hopefully Peak Diesel will have the FASS upgrade in stock for me.

 

[dresslered]

You might be alright if you are using a rubber hose as this will dampen the pulses by itself. I connected to the outlet side of the fuel filter with a rubber grease gun hose. The combination of the EOM rubber connection between the injection pump and the filter and the grease gun hose seems to dampen the pulses adequately for me and I have never had any problems. If you go back to the archives, you will see many electric sensors died when connecting directly to the injection pump. Also, try to mount the sender on something off of the engine like the firewall to dampen the engine vibration as well. Good luck with the FASS.

 

[Coalsmoke]

I'll take a look at those sending unit posts, it is mounted right on the VP-44 intake. Thanks for the head's up.



I stopped by Peak Diesel today and Harry and Louise (sp?) took great care of me as usual and sent me on my way with a FASS Platinum system with FASS's new Parker Racor filter setup which is rated for 2 micron filtration at 90GPH. I like the clear sediment bowl, have always like this type of setup on heavy equipment, now the truck will have it too.

 

[Coalsmoke]

I've got 1,500 kms on the new FASS now and like it very much. I would recommend giving Peak Diesel a call or email if you are looking at a FASS, they are nice units.