Hey everyone, I really need some help with this one. A friend of had her 1995 7.3 F-350SD tire truck stolen by her ex-husband. He tore the ignition lock out of the column and got the ignition switch into run, but didn't know how to get it to start, not a bright guy I guess. So he added a ON/OFF switch to the starting solenoid to start the truck. To turn off the truck, he would unhook the batteries. At some point he must have blown the 30Amp Mega fuss under the hood that controls the PCM and didn't know why it wouldn't start anymore and burnt up the starter. 3 months later the owner has got the truck back and I have been working on it in my free time to rebuild the steering column and found the fuse #22 blown. The truck started right up and ran for a few minutes, then quit running like you turned the key off and relay#2 is now chattering when the key is on. That relay is for the fuel pump from what I have found, but I thought this model truck had a mechanical fuel pump? What happened and why is the relay chattering now, did I miss something?

Thanks in Advance for all your help as her other truck is now having issues and she needs this truck for her tire business.

 

Is the #22 fuse still blowing? If so, I think that powers the PCM as well. If it's bowing it could be the fuel heater on the bowl, most recommend unplugging that.

Also, make sure all yours grounds are good. I had the clicking delay and it turned out to be the ground by the E brake

 

Thanks, I'll look at the grounds.

Fuse #22 fuse does supply power to the PCM, but it hasn't blown again.

Relay #2 says from what I've read is for the fuel pump? It's the relay that's chattering and now the truck wont run link the fuel is shut off again?

 

do you have efuel? if not then there is no relay for a mechanical pump

 

My manual says relay #2 is for the IDM on a diesel. On a gasser, it is for the fuel pump. You must be looking at a gasser manual.

 

swap that relay 2 out with horn relay and see if it stops chattering

 

I had this same issue.......it wasn't the relay rather a bad ground. Swap the relays as knotty said but i got $8.50 it does the same.

+1 to farmert, you are prob looking at the gasser

 

here was mine:

 

^^^^^^ +1; Chattering relay is almost never a relay problem. It's just the symptom. Typical voltage/ground issue. Turn the key, the relay closes, whatever it powers energizes, but with the connection issue, that draw pulls the circuit voltage down. This causes the relay to open. Open relay, no more load on that circuit, the voltage can recover. This allows the relay to close again and the load to power up again. Lather, rinse, repeat (several times a second).

Check main battery connections, connections to PCM / IDM, GP circuit and all grounds.