So I have recently did a body swap on my 7.3 I rolled. Put a body from another one this one. Before I took the old body off the engine ran fine. Nothing wrong at all.

Now that I have the new body on, I am stuck with a fuel shutoff switch. I read that it is suppose to be pressed down, but when it is pressed down, I turn the key and 4 relays under the hood click rapidly, 2 under the dash, and the drive side blinker blinks? Anyway, when I push it up, and turn the key, all the lights come on normally, wait to start light comes on. It'll crank good, the battery's are good, had them tested and fully charged. Checked ando triple check all battery connections and grounds. Anyway, it'll crank and want to start it fire up for a second and die. The low pressure oil gauge on the dash doesn't go up, but I think I broke the sensor connector for that. The fuel pump doesn't make any noise, the fuel bowl has fuel in it, but does fill up with fuel. So I'm thinking the fuel pump is somehow shorted out, so when I depress the fuel shutoff switch it makes everything go crazy. But even then the fuel pump doesn't make any noise?

Anyways, it's a lot to read but any advice on this would help, kinda stuck waiting for my brother to bring me my AE and computer back.

 

Test the fuel pump with a multimeter to see if you have 12 volts to the pump. If the pump is not making any noise that may indicate that a fuse is blown or there is a problem in the rollover safety circuit. The meter will tell you if you have power. If you have power but no fuel pressure, and no noise, the pump is bad.

 

Well I've figure this much out.

I am not getting any power to the pump. When the inertia switch is pressed in like it's supposed to be, that creates some kind of short and makes everything that's connected in that circuit go haywire. And the fuel pump still doesn't get any power. Now if the inertia switch is popped up, everything that was going haywire is working correctly. Except in fact the fuel pump. Okay now, when the inertia switch is pressed in and everything is going haywire. If I get lucky, it'll act normal for a minute when I turn the key on and the pump will work. But once as I start to crank, everything goes back to clicking and all that good stuff.

So tonight I will try and ground the pump to the battery directly. I'm pretty sure there is some sort of short between the inertia switch and the fuel pump. Because if I removed the relay behind the stereo with the inertia switch pressed in, everything goes back to normal but yet again, no power to the pump. But anyway, Ive triple checked fuses, relays, and swapped out the inertia switch with another one I had. All that is all fine and dandy though.


Also another thing off topic, my 4wd. The new cab came off a truck with a shift on the floor. Transfer case on new truck is a electric. The pigtail for the electric switch is on the new cab. But doesn't work when I hook it up. Thoughts? I've checked fuses, every fuse I could find. It has to be cab related, because everything on chassis and engine worked fine even after I rolled the truck.

 

I figured it out, I took a wire, grounded the fuel pump straight to the battery and now she roars like a lion!

 

Good job. That has to be exciting to see the light at the end of a very long tunnel. Congratulations on taking on a complicated job. Now one more thing.

You should check to make sure that the cab, the frame, the bed and the engine is grounded to the battery. The fuel pump draws a fair amount of current, so a missing cab ground would make the fuel pump not run. A missing ground can kill your electronic modules when blower motors etc send current the wrong way through the modules trying to get back to the battery. Do not confuse the small ground connections from various harnesses with the main battery grounds.

 

Yeah I feel as if I am missing a ground somewhere. As if the new cab never had one, because it was on a nonrunning truck I could never get to start.

 

Try disconnecting the power wire to the fuel pump and the inertia switch pressed down or in and see if everything goes crazy. If everything goes crazy you have a short from the inertia switch to fuel pump. if everything is good with only the pump disconnected and when you reconnect the pump everything is back to the crazy then I would look for the power source that feeds power to that part of the circuit. maybe the pump is pulling down the voltage due to it has a high current load. The load of the pump can pull the 12 volts down and drive everything on that circuit crazy.