jhennager

‘97 will only start when manually primed. The gas in the tank was bad so I dumped that, refilled, cracked the line and cranked it to ensure the pump was working well. That rules out the inertia switch I believe. I replaced the pressure switch and blew out the fuel line but there’s still no pressure at the fuel rail. Any ideas?

BareBonesXL

Clogged filter. Kinked line. Stuck open fuel pressure regulator.

Jimboy

I am with BareBonesXL, you need to change the fuel filter. It is probably filled with rusty water.
Let us know what you find.

jhennager

already blew out the line, replaced the regulator and the filter

jhennager

I changed that already, checked the emergency shut off, and I don’t believe this truck has a switch valve but I could be wrong.

jhennager

im going to quickly recap to make it clear what’s been done now:

rear tank and pump are new, front tank and pump checked and ok

emergency shut off good

fuel filter changed

line blown out

pressure regulator changed

pressure checked at rail- negative

16IngotFX4

Hate to state something so simple.
Is your pressure gauge working?
You should have a spray of fuel at the Schrader valve if the line is primed -you probably know that though?
Disconnect the filter again to check that you still have fuel. If possible, watch the pressure change at the now broken fitting while somebody else turns the key. Of course practice safety such as eye protection and put out the cigarette.

BareBonesXL

Had a discussion recently about the pressure regulator. I called it a "relief valve" and started some conflict. But, regardless of terminology, the pressure regulator blocks fuel flow back to the fuel tank until a certain pressure is achieved. No offense intended but you seem to be replacing parts without really understanding what they do.

Have you pressed the Schrader valve, the thing that looks like a tire inflation valve on the fuel rail, to see if fuel comes out? You say that there's no "pressure" but it's not clear how you determined that.

There's really not much to the older fuel systems. A pump, some hoses and tubes, a pressure regulator that blocks flow back to the tank. No fancy pump power modulation. Just pump, flow, block it until it pushes its way past the spring pressure at the FPR. The only other place for fuel to go would be straight through an injector into a cylinder.

Jimboy

jhennager,

Your statement "pressure checked at rail - negative" points to the issue. I assume you are using a pressure gauge attached to the fuel rail Schrader valve.

Three pumps??
First check all fuses and relays (take a picture before removing any fuses) by pulling and reinserting to refresh electrical contact surfaces. Look for corroded ground connections.
I beleive (others please confirm) that in your dual tank system you have three fuel pumps, a boost pump for front tank, a boost pump for rear tank and a high pressure pump that pressurizes the fuel going to the injectors. This system also includes a switching valve that gives you the option of front or rear tank. Assuming you have the three pump system please confirm (you will need an assistant) that;
1) Trace fuel lines (look for kinks in the hoses or tubing) from each tank and find the switching valve and confirm you can hear it switch as in cab selector is moved from Front to Rear
2) Confirm Rear tank pump runs when selected to Rear
3) Confirm Front tank pump runs when selected to Front
4) Trace fuel lines forward and confirm you have a three pump system - If you have a three pump system confirm high pressure pump operates when ignition switch is placed in RUN and fuel rail is depressurized.
Others please chime in so that we can get jhennager back on the road.

Jimboy