I have a stock 2002 (old body style) that began showing erratic fuel pressure this morning and once again this evening during the commute home. I have a Westach electric gauge that I installed 6 months ago and it has consistently showed 14 at idle, 12 at cruise, hard to pull it below 10 with aggressive throttle. This morning was different as it would begin to bounce between 4 and 14. It was cruising at about 6-8 on the commute home and occasionaly it would come up to 14 when sitting at a light. It was also a little strange that when I got home I played around with the lift pump by bumping the starter to see if it was even working or what it sounded like. There were a few times after bumping the starter that the lift pump would not sound like it was working. I just checked the fuel filter and it is clean. I have a 1/4 tank of fuel treated with PS. There are 50K miles on the truck. I will be leaving the truck at home until I figure out what my options are. Thanks for any advice on what to do next.

Edited to add that the creepy thing about this is that the truck drives great and I would not have even known that my fuel pressure was bouncing around so much without an in-the-cab gauge.

 

Your lift pump is on its way out. Say your goodbyes and go get a new one.

 

What type of pump should I get? I have heard some reports that the in-tank dealer conversion is less than ideal. Should I just use the same type of lift pump at the same location under the hood? The local NAPA dealer has a in line lift pump for $220.

Thanks!!

 

I was also curious how I would diagnose an electrical problem since it appears that the pump activity is intermittent. I just want to rule out a problem in the wiring before I yank out the old pump.

 

Your symptoms are exactly the same as mine when my lift pump died. I even had the in tank pump from Dodge installed and it only lasted about 10 months!! I personally have a Holley Blue on the frame in front of the tank. For the price of the pump from Dodge you can get a better aftermarket pump with bigger fuel lines.

 

Could very well be sucking air. Mine did the same thing. I found the connection between the steel line from the tank and the transition to rubber for the lift pump was loose and sloppy. Pushed them back together and used two small hose clamps. Stock pump has been fine for 20k miles. In my humble opinion the Carter pump is pretty good.
The second part of the TSB on the fuel pump is to check for air bubbles in the suction line. I would wager that most of the lift pumps are replaced due to this poor connection. Every time the engine "twists" due to it's torque it pulls this connection apart just a little.
Crawl under the truck by the drivers door and look at the lines and you will see what I mean

 

Mine had erratic readings, but the pump was working (I tested it where I could hear the pump and the readings were jumping around). Eventually turned out that the sender wasn't grounded properly. First check to ensure the sending unit for your gauge still has a good ground and signal path (and the gauge as well).

I used the Holley Blue mounted on the frame rail and get good pressure now. And you can pick up a replacement Holley at almost any AutoZone for less than $100. I'll probably just buy a spare to keep under the seat as an emergency replacement. If you don't want to worry about replacing it, go for a FASS. Much more expensive, but they have a great warranty and lots of folks on here use them and love them. But where I have the Holley mounted I could likely change it out in WAY less than an hour with a few basic hand tools so I'm okay with that instead of the FASS. To each their own.

 

Your problem sounds just like a lift pump failure. If the gauge was reading before, I would start with the lift pump. I have the Carter pump with the Vulcan relo/big line kit. I can change the fuel pump out in about 10 min. on the side of the road if needed.

 

Forgot to say. Listen for the fuel pump noise to change pitch. Mine went to a higher pitch when the pressure tanked. Do the 25 second bump to hear it as you can't hear the pump with the engine running. I have heard this is the pressure regulator/relief taking a crap on the pump.

 

I need some clarification:

Will the lift pump run every time the starter is bumped? I bumped the starter about 8 times in a row and 3 times the lift pump did not activate.....

 

Great Question. I noticed the same thing with mine, but I am also experiencing some FP problems. Anyone?????

 

Since you have an elec. gage, it could could be your sending unit. Make sure your ground for the gage is good, clean and tight.

The best way to test your pump is to unscrew the elec gage sending unit and screw in a mech. gage. You can leave it as temporary for a while by running it up by your windshield where ever it reaches to by you wiper blade.

 

Finally found some time today to check out some connections:

1. No loose fuel line fittings.
2. No loose wires to the gauge.
3. Sending unit ground wire attached to firewall was loose.
4. Pressure line from VP44 test port was just finger tight.

So I disconnected the pressure line, re-applied gasline teflon tape to both ends, bled off air from sending unit end. Tightened the ground screw connection point and went for a test drive. Test drive went without event and everything worked "normal."

I exepct the lift pump to fail (as do many of us here do) and I need a list of tools that I will require to change out the pump while on the road. I will start carrying a spare pump in the tool box as this little event has been a good lesson that the stock lift pump can fail at any time.

Thanks for every one's help and advice!!

 

Just your basic assortment of hand tools is sufficient to change a pump. Wrenches and sockets in particular.

 

Now you can plan a pump relocation at your convience but don't wait too long...winter's a comin'.
I bought my Carter 4601HP from Summit for $98 a little over 3 years ago and it's doing just fine.
The Vulcan lift pump relocate kit get's you the wiring extension and hoses.