Engine/Transmission (1998.5 - 2002) Changed Fuel filter-fuel pressure dropped?

[FClanton]

I have a 2001 2500 2 wheel drive. I had my transmission serviced and had the mechanic replace the fuel filter that I got from Genos as well. When I took the truck in it was reading 10 psi on my electric fuel guage attached to the top of the billet fuel filter canister top sold by Genos. When I got the truck back the fuel pressure was 5 psi with no fluctuation. The mechanic pulled the filter and noted a difference between the two filters, both from Genos. They got another filter from auto zone and installed it. My fuel pressure was 7 but climed to around 9 as I returned home. The next morning I drove about 25 miles with the pressure starting around 9 and it increased to 10 and stayed there for the duration. In the afternoon I made the return trip. The initial reading was 4 psi which did not change. I have tried restarting the truck several times but the pressure remains at 4 psi. When I first cranked the truck in the afternoon I noticed the guage needle went backwards instead of the intiial jump it usually makes? The lift pump makes the same sound it usually makes when first turning on the key. Any ideas???

 

[JLandry]

Before you go any further, get a "second opinion" on the fuel pressure by connecting a fuel pressure test gauge to the fuel inlet port (Shraeder valve) on the VP44. Geno's sells as nice high quality unit in the correct pressure range, but inexpensive (though less accurate) kits can be purchased from places like Harbor Freight Tools and your favorite local auto supply store.

Many times fuel pressure behavior such as you're describing is simply caused by a failing fuel pressure sender (if electric) or a leak in the line between the isolator and the gauge (if mechanical). If the later, be sure and reset the diaphragm (push back toward the fuel filter) inside the isolator after you repair the leak and before you refill the line with antifreeze.

If you get the same readings with a fuel pressure test gauge, then the lift pump should be replaced next. If that doesn't cure the problem, then next you'll probably want to examine the fuel lines for damage and also the inlet screen inside the tank for possible restrictions.

Best regards,

John L.

 

[mwilson]

If you gauge passes the test you may have caught the lift pump in the early stages of failure.



I am not so lucky as a rule... ... . :-laf



Mike.

 

[SnoKing]

You sure that where you have the gauge connected is post filter? Sounds like it is pri-filter. Is the port in the center of the billet cap, getting pressure reading for the inside/center of the filter? Did you bleed the air out of the line to the sender?



Having a test gauge that screws on the VP44 is handy at times like this. SNOKING

 

[CAPTPHIL]

I have been using the billet cap for the last 200000 mil. The pressure sender is mounted in the cap. To change filter, I unplug wire harness and unscrew cap. The early model of the cap which I have does require trimming a SMALL amount off the edge of the top filter on the new model filters. The newer billet tops are a hair larger inside and do not have this problem. I only use Fleet Guard Filters. I would check the fit of the filter by inserting it in cap before putting it in the canister.
Good Luck Capt Phil TDR since 98 over 1mil. mi. on 24v

 

[FClanton]

Thanks for the info. Sorry I am so tardy in responding. I had to go out of town and did not have access to an internet connection.



I returned this evening and cranked the truck. The pressure reading was 1 PSI. When I turned the key to initiate the lift pump I noticed the needle to the guage moved left lower than the lowest mark on the Westach electric gauge. I am not sure if this indicates a failing sender or not but it has not done this in the past.



It could be that when the top of the filter canister was removed one of the wires was not resecured properly, I will check that in the morning. I will get the aux pressure gauge and double check the pressure before I move the truck.



I have had the billet top for several years and have never had to shave the top of fuel filters before so I guess I have one of the newer billet tops.



The pressure reading is from the center of the billet cap which I guess means the pressure reading is from the center. The gauge is electric and I do not think there is any way to bleed the air from the line. Unfortunately, I am not that competent with the mechanics of the engine or it's components.



Thanks for the replies... .

 

[FClanton]

Thanks again for the information. I got the fuel pressure test guage from Genos. When I checked the pressure it read a steady 12 PSI. I have a new guage on the way.

 

[RustyJC]

When I turned the key to initiate the lift pump I noticed the needle to the guage moved left lower than the lowest mark on the Westach electric gauge. I am not sure if this indicates a failing sender or not but it has not done this in the past.

I ran a dual combo (pre-filter and post-filter) Westach fuel pressure gauge in my 2002 ETH/DEE dually. Fuel senders are the weak point of this gauge package. I'll bet I changed over a half dozen while I owned the truck. It finally got to the point where I always carried a couple of spares and could change out a sender in 10-15 minutes in a service station driveway. I've had senders go straight to zero, others that jump all over the gauge, others that indicate fuel pressure changes in steps (15 PSIG for awhile, then 8 PSIG, then 2 PSIG, then 15 PSIG again) - the readings straightened out on all of them after the sender was changed out.



If you have your sender mounted with the electrical terminals facing down, many times you'll find a bad sender (ruptured diaphragm) when fuel starts dripping off the terminal bolts - you'll also get a strong smell of diesel fuel in the truck along with a puddle on the ground.



Rusty

 

[FClanton]

Thanks Rusty, based on other observation by TDR members I got a test guage from Genos and checked the pressure at the vP44. It read 12 psi while the guage read 3-4. I have ordered a new guage and pressure sender from Genos but it is back ordered. I plan to check the pressure periodically with the test guage until the guage kit is off back order. Now, my transmission is on the fritz. I have a new post related to the trans any assistance on that would be greatly appreciated as well.

 

[RustyJC]

I have ordered a new guage and pressure sender from Genos but it is back ordered.

If you're staying with the Westach, there's a 99% chance that all you need is a new sender. I never had a problem with the dual combo Westach gauge. I had 2 senders in the truck as spares when I sold it to a friend when I took delivery of my 2011.



Rusty