94 Lightning.When I purchased the truck only the rear pump was working. Drove it on the rear tank for the first year. The rear tank developed a small leak, so I decided to replace both pumps and tanks. All was well for 5 years. The other day I went to start the truck, and it wouldn't start. I was on the front tank, and noticed there was no fuel pump noise. Switched to the rear tank, heard the pump, and it started up. Yesterday the truck wouldn't start. I heard the pump running, so I assumed it was an ignition issue. Spark was good. Checked fuel pressure, and it was zero, but pump would run. I try to keep at least half tank of fuel, so I should have enough gas, but I added a couple more gallons just to make sure. Still no fuel pressure. I have read thru Steves articles on the fuel pumps. I see one where it states you need to close off the tubes on the disabled pump, to run on just one pump. I don't have a transfer valve, just the two pumps on their own, and have been driving the truck on just one pump. Some confusion on my part. Could the fuel from the rear tank be going into the front tank, instead of going thru the filter to the engine? It seems like with the pump running I should have some sort of pressure even if it is low. I haven't disconnected any lines yet, but I guess I will remove the line to the filter next. Any other ideas before I pull the bed off? Thanks

 

Unless something happened to the pickup tube and the pump is sucking air.

 

Copy that. Just seems odd. It started a couple days prior, and I haven't driven it.

 

Probably pumping into other tank. There was a recall back then that added check valves to both pumps' return lines from fuel rail. The check valves will eventually seep through and no longer seal and will have to be replaced. Pretty simple, pull bed and pumps are accessible. If pump motor is out you probably cannot find replacement that fits properly (except in junkyard) but it's possible to move new motor to original frame. Available from LMC and other parts companies. Some times when both tanks are full the gas will run out of the filler tube and down the side of the truck from the idle tank. Good Luck!

 

If you have aftermarket pumps then the check valve shouldn't be an issue. Even then, the crossover issue was a problem with the 93 models anyway. Another known fuel type issue is the factory Fuel Pressure Regulator failing and/or leaking by, and causing low/no pressure issues. Some of the late 93'a and 94's had faulty regulators that would cause low/no fuel pressure issues.

 

Haven't gotten back to it yet. I planned on driving it on the lift when the front pump went out. That aint happenin now that both pumps are inop. Getting ready to pull the box, and see what is going on. Will update with results. Thanks for the inputs.