raven564

So, driving to work today truck died. I've been seeing inconsistent lift pump pressures, so had one on order (It's coming tomorrow... go figure *sigh*). However, this didn't really seem like a lift pump failure... or something that would be caused by inconsistent lift pressure. One second truck was running, next second... truck was dead. I pulled the schrader at the VP44, and there is fuel... I put a container under it and I would say I had a quart of foamy fuel in 10 seconds. Not ideal, but not nothing either. Anyway, no codes... no nothing.

My (stock) lift pump recently started fluctuating between 12-15 at times, then would drop down to 5-8. It was intermittent... If I would kill the engine, restart, it would go back up to 12-15.

Did I lose my VP44? It almost seems like something electrical... ECM? Wire? Truck was running... then dead. No roughness, no sputtering... however, the lift pump is now acting differently. It seems to rarely reach 12 lbs in the driveway after a tow home.

I'm going to replace the lift pump tomorrow (was already planning to do that proactively) but if that doesn't cure it, I thought I would get this thread started. What electrical things should I check? I'm handy with a multimeter, just don't know where to check. Also, once I get known good fuel pressure, with no codes, how can I diagnose if it is the VP44? Truck just spins over, no "fire" at all.


Oh, one more thing to add... the truck sat for 3 years. Just went back on the road again about a month ago.

s-cube

Have you cracked open the injector lines to see if you are getting fuel to the injectors? Did you possibly run out of fuel. The fuel gauge on my 01 hasn’t worked for several years, just reset the trip meter each time I fill up. My lift pump was doing the same thing and the new one fluctuated too. After cleaning all of the neg ground connections it worked fine. What are you using to check codes?

raven564

Nope. But at the banjo inlet to the vp44 there is fuel. Pulled the schrader and I get flow out of the port. Not out of fuel. Fuel gauge works as expected. About 1/4 tank in there, and it's been fluctuating in pressure since completely full.

Ordered an aftermarket pump from Rock Auto and the damned thing came in the mail without the 90 degree adapter fitting. I'm actually considering going buy another one from Napa or AutoZone to get the adpater, then once i get the replacement from RockAuto returning one or the other to RockAuto. Pisses me off when parts come without required pieces... So, unless I go spend more money at least temporarily unless I just keep it on the shelf as a spare, I'm SOL until Rock Auto sends the missing component... and considering it would be Friday before it would ship, I may still be down until Monday. I was going to install it tonight as step one of troubleshooting.

As for cleaning the grounds, which grounds are you referring to? There's a lot of grounds in the harness... if you mean at the lift pump itself, I've pulled the connector and at least visually inspected it.

Lary Ellis (Top)

2nd gen trucks are well known for the fuel gauge to be off....I know you think there is plenty of fuel in it but I would add some just to be certain....cheapest fix it I am right

Foamy fuel sounds like a lot of air involved like it is sucking off the bottom what little it can get.

raven564

Well, I ran several quarts out of the tank. I seriously doubt it is the fuel sender. Besides that, the truck never bucked, sputtered, or anything when it quit. One second running fine, next second completely dead and never fired a cylinder again. The gauge never read inaccurately before, and I know I filled it up to the top less than 400 miles ago. Unless I also developed a leak at the same time, it is not lack of fuel.... Additionally...


I managed to get the new pump mounted even without the right angle fitting, at least enough to troubleshoot. With 14 lbs steady pressure going at the vp44, still nothing. Gave it plenty of time to purge air. notta. Not even one firing cylinder or attempt to start. Had to stop to put the batteries on a charge. I've done quite a bit of spinning her over last two days, so before I run the batteries down too much stopped to charge. Plus the batteries are at least 5 years old.

I'm guessing right now that my vp44 bit the bullet unless it's electrical? I'll figure out how to pull the connector on the back of the vp44 and hit it with a multimeter to see if I have a good 12v going to it this weekend per this guide: https://www.bluechipdiesel.com/vp44_diagnostics.html , but I'm expecting the worst. Checked all the fuses, swapped relays, etc.

raven564

To answer an earlier question, I am reading the codes by doing the key trick. on and off three times... no codes thrown.

Desert5600

What did you find out?

Busboy

Plug in a code reader to see if it can communicate with the ECM. Often when a computer says there is nothing wrong... it's the computer.