Liftpump final chapter ,Hopefully!

[DNunemacher]

Just picked truck up from dealer they installed a new lift pump #5080885AA, After 4 months of waiting they determined the lift pump was only working sometimes. They stated the fuel pressure was as low as 5psi and 10psi at idle, aopsi and 15 psi at red line. You guys solved the problem with my first post maybe the dealer should join. You peoplereally know what you are talking about look foreward to more help when needed. Will take truck for a good drive tonight and really check it. I am still trying to figure how to check the fuel pressure myself. I have a gauge that I threaded onto the fitting with the black cover on and got no reading any help would be appriciated.

 

[JEMOORE]

Easy fuel pressure gauge

You may have already seen this post but if not here it is again. I am still happy with this set up and will probably keep it this way from now on. Hope this helps.





JEMOORE





Registered: Aug 2001

Location: Kentucky

Posts: 18

Easy and Cheap Fuel Pressure Gauge

Get a 30psi gauge with the pipe thread coming out the bottom of the gauge. Get the tubing kit that is for hooking up mechanical oil pressure gauges, etc. ( I saw these at NAPA for around $5, gauge can be found for around $10-$20 mine was priced $8. 49 but I'd had it for awhile. ) If you have a standard transmission you can lift up the boot around the four wheel drive shift lever. Drill a small hole thru the floor pan at this location. Be sure it is in a position not to hit anything underneath. Be sure to use a rubber gromet. (This is also a good place to run a CB coax to the outside) Use wire ties to route the small hose up the fuel line, and dip-stick tube, to the fuel filter top. The gauge can be velcroed to be held in place on the carpet just in front of the shift lever. Nothing is seen but the gauge. Be sure to check for fuel leaks after all connections are made. This was meant to be temporary, but as good as it seems to be working I may just leave it that way. Just won't be able to see gauge at night. I don't much like the plastic hose but I've used it in other apps. for years with no problems. This is only an idea and the way I did mine. Use it for what it is worth.



I also checked the voltage to the bottom of the stock lift-pump. When you first turn on the key the voltage GOES TO 12 VOLTS. The pump runs a few seconds , builds up pressure, and stops. When the truck starts, the pump voltage goes back to 12-13 -14 volts, what ever the Alt. is putting out. What am I reading about the duty cycle and different voltages going to the pump? Am I missing something? If I am right seems this would eliminate low voltage as a cause for the failures. Also it would be possible to eliminate the stock pump altogether, install a more reliable pump closer to the tank, use the stock Red wire to run the new pump and not have to use a relay or run two pumps.



What do you guys think, am I on the right track? I still say anyone who has a failed pump needs to take it apart to see what actually is failing. Please post what you find. Also, remember, a zero reading WTO POST-filter doesn't necessarily mean a failed pump, could just be a dirty filter. I'd sure like to get this figured out to restore my confidence in my truck's reliability.





__________________

"99 3500 Quadcab, 4WD, 5 SP, 3. 55, BD Ex. Brake, All Factory Opts. Coachman Slide-in Camper.



Last edited by JEMOORE on 08-07-2001 at 10:24 PM

 

[Valkyrie99]

I've been reading all the posts and feeling a little lucky, not having a lift pump problem. Well I have to join the ranks of the many. Changed the fuel filter this last weekend. When I went to prime the canister, no pump action at all. Lots of noise from the pump but no fuel. Actually took the shop vac and got it primed.



I called Cummins in my area and they have -6 in stock and the warehouse in Irvine CA has -32 in stock. Could be years before I get one from them. TST in Indiana had one and is on its way. Eventually I will change it to a frame mounted aftermarket pump when I have the time to play.

 

[Big P]

What are the chances that these new pumps will show up on the early 2002 Cummins motors?

 

[Steve St.Laurent]

My guess (HOPE) is that the latest rev lift pump is the one on the lines now. Whether that will solve the problems with them or not is another question - the lift pump has been revised approximately 10 times since 1998 and they're still unreliable thus far! That's why MANY of us are researching alternative solutions to this problem .