When I put the SECOND LP in a month into the Truck, I noticed that when I disconnected the pressure side fuel line, the fuel contents of the pump spilled out. When I disconnected the supply line from the pump, not much diesel from the tank / Fuel Sock / Fuel line. leaked out. Am I going to have to drop the tank, replace the sock, and blow out the fuel line before trying to start the truck again??

 

Fuel socks do get plugged and aftermarket socks have too fine a mesh.

Often though,a hole in the line lets in air that breaks the suction of the siphon effect that prevents the supply side from leaking a lot of fuel when you disconnect it from the LP.

 

I bought another AC Delco Fuel filter from Auto Zone, and will install it, and an AC Delco OPS later today. (It's only 6:30 AM, and I haven't even had my coffee yet). The mechanic at Crawford GMC in El Paso, SNAPPED the black plastic bleed screw on the filter that I had installed three weeks earlier, but the told me that I could pick up the truck for free, and not pay them for the work, (DEMOLITION??), that they did to it, troubleshooting the system as needing ANOTHER lift pump, the one that was in there was three weeks old.
I have a new inline blade fuse holder, and some 30 Amp blade fuses, so I am going to hot wire the lift pump into a hot when switch on circuit, or if I can't find a suitable one, straight off the positive terminal of one of the batteries, through a dash mounted switch. (As a Pilot, I am very used to turning on and off, boost pumps on Aircraft). If I blow another lift pump, for 400 dollars, I can but a NEW Bed mounted 96 gallon fuel tank, with a bottom of tank feed, that will have NO sock, but an external, screw on canister filter with water drain in the feed line to the pump. I won't even NEED a pump, where I am going to mount the tank, if I use it, the pressure head will be in excess of 3 to 7 PSI, so in can Gravity feed the main injector pump.

 

first off why are changing lp?, if you put a second lift pump in and still having original problem, check voltage at lp, if it works than, what i did was bought a fuel pressure gauge, and mounted it on the outside of my drivers sideplastic grate and ran a fuel line to a T at the bleeder valve by youre oil filler tube. this way i can watch my lp pressure at all times, i love it there! No guessing about fuel from youre tank to youre fuel filter canister, when you turn key at start up i typically have about 6lbs when running around 4-5lbs, i wish i would have done this before dropping the tank (twice) but at least it was comforting knowing it was clean and no leaks at tank, GOOD LUCK

 

The T-valve is unfiltered fuel pressure.

Might be better to connect the gauge between the fuel manager and the IP to add the ability to monitor filter condition?

 

The reason that I changed the lift pump, was that the pump that I put in quit running. The people at Crawford GMC in El Paso told me that the pump was bad, and I wasn't going to pay them the 360 dollars that they wanted to replace it, so I and a trucker friend of ours took his pickup to the dealer with a tow dolly, and brought the truck home, where I put the SECOND replacement pump in. I think that the OPS is screwing thincs up, when the engine is running, the needle will fluctuate between whatever valur it is readinf and a different reading either ten to fifteen pounds above or below the other reading depending on WHICH reading is correct. these fluctuations are constant every second or so. I would LOVE to take the power wire to the lift pump, and run it not from the OPS or Realy, but from a hot when ign is on or start. Problem IS that these 1998's are SO computerized, that I CAN'T find WHERE to tap from. I WAS going to tap the powered side of the Air conditioner blower fan, because the AC doesn't work anyway, but I CAN'T figure out how to access it through all the plastic in the way inside the truck. I don't know how long THID pump is going to go before IT breaks.
Brie

 

True that would give u a precise lowside fp after canister but this was a easier location to install and to inspect for any fuel leaks, Easier to remove filter and inspect canister for debris than it is too crawl around under the truck

 

AC Delco ONLY for OPS on these trucks-BWD are often bad right out of the box.

That said the OPS is only backup/secondary power for the LP in OBDII trucks,it should only work when you shut the truck off and oil pressure bleeds off,the rest of the time the ECM activates the LP relay to run the LP and that system works very well.

 

Do u have the old lp? if u do take some some 14 gauge or so wire and hook the leads directly to the battery and the push harness, that old pump might not have ever been a issue, as far as the ops, i have replaced mine because i was fixing a fuel line at the inlet to the filter canister, its a simple swap and i think it was 40$ and the ops is in that same lp circuit might be a good way to go, i would still put in a lp fuel gauge

 

always do a series of tests when replacing a lift pump. Once I get to the point of having the lift pump hotwired and the outlet disconnected, I put a hose on the outlet and run to a container. If I have No fuel I disconnect the lift pump, add another hose and try running fuel from container to container. If the pump is working I try blowing the lines with air. Make sure the fuel cap is OFF. Check the fuel line for leaks while your down there.
If that doesn't solve the problem, it's time to drop the tank.

I once had green oak leaves in my tank covering the sock. I think some youngster installed the leaves