Hi guys, looking for some help here.....working on restoring my 89 convertible. Engine wiring harness was pretty hacked up by PO so I replaced the complete engine harness with a good one from a donor truck. After installing it, I have everything working as it should except it won't start. It cranks strong as ever but no start. I do not hear the fuel pump kick on when I turn the key and do not get a spark. I verified all grounds are good. When I jump the ASD relay contact I hear the fuel pump kick in, so I know it still works. I verified that the SMEC has power on pin 41 constantly. Wondering if SMEC could be shot. Truck ran ok before wiring was replaced so I'm certain it is my wiring. I have the FSM and going through wiring diagrams it looks like the fuel pump and ignition are fed from the SMEC so I'm suspecting it at the moment but not understanding the circuit completely. Appreciate any help while I pick away at it.

 

Fuel pump and ignition should both be switched through the ASD; so if it's not switching, you won't get spark OR fuel.

You may need to check the wiring to the ASD and make sure it's in good shape.

Also, one person here found that the round recepticals in the 60 pin connector were getting loose due to age; might need to remove each one, tighten it up, and put it back in (again, check the FSM on how to do this).

That's where I'd be checking, anyway.

RwP

 

I just looked over the system again. Took apart the 60 pin receptacle but not seeing anything obvious. I have 12V at the input to the SMEC on pin 41. Should I be getting 12V output on pin 10- Ignition Coil Feed Fuel Pump to allow the engine to Start? Got to be an open wire here somewhere. What pin or pins should have voltage output from the SMEC to allow the engine to start. I also noticed that the -12V wire to the ignition coil has some cracked insulation. It doesn't appear to be the root cause but maybe I should be looking deeper at it?

 

You'll get a short pulse, then it will not turn back on until you're cranking it.

RwP

 

Thanks for your help! Found that the ignition terminal from the previous wiring harness was burned off which must have led to the hack job wiring the PO did. Ran a new wire inside the cab to terminal 47 at the 50 way plug. Back up and running!