Well I took it back today and said it "was broken." They just kinda looked it over and gave me a new pump. Took one hell of a load off my mind!
If you guys don't mind giving me a little more help in a technical sense I have a couple questions:
I'm trying to get my '86 running. It's a 4x4 standard cab (dual tank) with a 2.9/manual trans. A friend of mine hit a Suburban with it and evidently that pooched the fuel pump(s).
I have replaced the high pressure pump, the fuel filter, the pump relay, and checked the inertia switch. All test OK. Front tank doesn't have much gas in it, rear tank has about 1/4 tank. Battery is good.
My problem is that I'm hardly getting any pressure at the fuel rail. If I blow air through the return line (blue one/passenger side of the tank, right?) on the rear tank, I get gas out of the supply line right at the FPR, so the lines aren't plugged. However, when I ground out the high pressure pump with a gauge on the fuel rail (all lines connected,) I'll get somewhere between 0 and 15 PSI. The pressure also rises very slowly. Testing the pressure in my '88 2.9 yields almost instant 40 PSI. After the pressure gets up to about 15 PSI the truck will start and idle for a few seconds before starving for fuel and then stalls.
This indicates to me that the pump in the rear tank isn't working, or something else. Maybe the tank check valves? the grommets in both aren't great, but don't leak unless I blow quite a bit of air into the tank with an air compressor.
Voltage at the tank pump will jump up to about 6 volts and then drop down to around zero, every time, in about 5 seconds. According to Chilton's it should stay steady around battery voltage. I don't really want to mess with the wiring harness and am considering just putting the pump on a toggle switch in the cab.
Any suggestions/comments? If my ideas are crap let me know. Also keep in mind for the toggle switch idea that inertia swtich safety thing isn't my first concern...this thing is going to be trail driven only, very rarely in town and probably never on the highway.