This was another tough project for me. I have been fighting fuel pump issues for a several years, and have probably changed six fuel pumps on my truck in the past five or six years. At least one fuel pump was defective out of the box… the internal fuel pump check valve was not functioning. Do not buy cheap fuel pumps. The access panel that has saved me from delays, tow bills, and mechanic bills caused by failed fuel pumps, and is shown in the photo below.
Initially on this repair, the truck had little or fuel pressure at the rail. The substitution of the Walbro fuel pump did not resolve this issue, but the Walbro fuel pump was clearly “priming” with the ignition. I was measuring fuel pressure, without a fuel pressure gauge, by checking the shraeder valve at the rail with a small screw driver. There was sometimes pressure, and sometimes no pressure- “on” or “off”. This primitive method was adequate for all of my previous fuel pump replacements. But the lack of a fuel pressure gauge and primitive reading almost surely led to confusion later in this troubleshooting effort.
When I was finished with the fuel pressure regulator project, the system still did not seem to be building fuel pressure consistently. But it was discharging fuel through the fuel return line. Per the suggestions in this thread, I crimped/corked off the soft return fuel line above the tank. I did this with vice grips and a pair of paint can screw drivers, making every effort to protect the fuel line. This did “deadhead” the fuel pump, but did NOT cause any other problems.
But when I was done, I still had no-start. I communicated with
@donalds, who gave me several insightful suggestions (1j. next time, get a fuel pressure gauge. The existing fuel pressure is quickly discharged from the fuel rail at the shraeder valve, does not have compression characteristics like tire pressure, and is tough to monitor. (2). The fuel pressure that was currently squirting rapidly from the shraeder valve was probably an indication of adequate pressure at the rail. (3). Re-check fuel pump hose connections and the assembly in the tank. (4). Check crank shaft position sensor, as this would shut down fuel pressure and spark during engine cranking and would contribute to my confusion.
I did all of these things that Donald suggested, and the truck fired to life! The truck seemed alive. Yay.
I followed this wisdom, and many of the suggestions and thoughts in this thread and from this Forum. I am sure that most of the ideas that did not help me here were based on inaccurate information I provided. I was humbled, and grateful for everyone’s help. Part of this final comment is an apology for my lack of mechanical expertise. But I did want to complete this thread with a conclusion, as the threads that vanish into nothing do not seem very helpful.
As always, I want to thank everyone for the help and ideas on this Forum. Without this support, it is almost certain that my truck would have been mashed into a beer can at a salvage yard years ago. Thanks again.
Drive safe and have fun.
