Archived replaced lift pump - STILL DEAD

[akline]

My brother in law has a 1999 24v with the Edge Comp box usually set on #2. Three weeks ago it began to lose power as if a fuel gelling problem, and finally left him sit that afternoon. Fuel filter replacement and lots of additive and back on the road.

Left sit again a few days later. Fuel filter, ether (don't try this at home), and still no go. We finally used an air nozzle to blow back through the fuel supply to the filter, and flow with the lift pump running and a banjo fitting open improved from what had seemed weak. Test pressure at the filter (before and after were similar) showed around 10 at the most, with a sharp drop under quick throttle action. The truck sounded as if it would skip a beat every so often when idling, and finally just died. The air nozzle trick again got us running for three or four days. Finally it just died right on a spot, and we noticed the lift pump was not making any noise at all even after bumping the starter. Convinced it was the pump, we went for a trailer to bring it in (with my truck ).

We needed a way to load it, so decided to try starting it, and suprisingly got it to run enough to easily load, unload, and pulll in the shop. After replacing the lift pump

(we found this is done reasonably easily by removing the plastic wheel well liner and bending the wheel well sheet metal partially out of the way so as to access the lift pump from the side)

we started the truck after cycling the lift pump a few times, and it ran! After about a minute the fuel pressure jumped from too low for our guage to read to a solid 15, sometimes 20 pounds.

When the test run out of the shop resulted in the engine stalling 3 minutes later, we were dumbfounded. Now again, the lift pump makes no noise at all.

What in the world is wrong?

is there a way to verify the lift pump is receiving proper if any voltage, and what controls when the lift pump runs? Any help would be much appreciated

 

[Sticks]

Odd, usually the VP44 has enough gusto to keep the truck running even with a basted LP.



The LP should have a constant 12 volts to it while the truck is running, and the first 20 - 30 seconds after you bump the starter.



I wonder if the tank has some algae in it and has clogged the fuel pickup.



Try giving the truck an IV. Run a hose from a 5 gallon fuel can to the inlet of the LP and run the truck that way to see if that helps. If the tank has goo in it, it may have clogged the LP. You can if you are very careful, remove the top of the LP (3 studs) and lift the cover to inspect the pump vanes. Careful, the screen will want to come up with the cover.



Have you checked for codes?



Uninformed guess, your VP44 got baked (Edge Comp - tapped fuel wire)

 

[blacksheepdiesel]

Does the 24V have a fuel strainer on it like the 12V? If so, have you checked it for blockage?



Also, have you tried these things with a full tank of fuel?



Trent

 

[Michael Hughes]

If I remember right, if the engine was running and dies, you have to turn the key to the off possition and the bump the starter to get the LP to run.

 

[Steve Campbell]

I am going to chime in with sticks....

I feel the problem is with the pickup module strainer/membrane. The idea about a remote supply of fuel hooked up to the lift pump should answer that question.

 

[scotty1]

Also, clean the connections for the lift pump power.



Check for codes on the odometer by cycling the key forward but not starting three times.

 

[RankRam]

Originally posted by scott1

Also, clean the connections for the lift pump power.



Check for codes on the odometer by cycling the key forward but not starting three times.

There is not a code checker on the odometer on a 99.

 

[MCummings]

Probably a dirty fuel pickup. Maybe have algae in the tank?



I would search for "algae" here on TDR. You should get some good info.



Merrick

 

[akline]

some responses/further questions

One important thing I want to mention is that the lift pump makes no sound of running at all. (we need to check the supply voltage to the lift pump) Also thanks for the info about the screen in the LP. Maybe a suction guage on the tank side of the LP would be something to try. The next question is what feeds power to the lift pump? There must be a relay somewhere. So, how then do you check for codes on a 99? Would there be a light or anything to indicate if a code is there to be read? At what point do we give up and head for somebody's shop? Thanks

 

[Sticks]

Auto Zone will check your codes for free. Just because the MIL lamp (check engine) is not lit, that does not mean there are no codes.



Do your own diagnosis, it's a helluva lot cheaper than a shop. Find the problem and then if it too much for you to handle, take it to the shop.



The PDC in the engine compartment behind the drivers battery should have the relay for the LP. If I remember correctly, they are all the same type, so swap them around and see if that gets the LP running.