I have a no start condition on a 1986 F-700 w/ 370 4V I have momentary current on the fuel pump while cranking and then lose it, I'm assuming it has a relay and also a pressure switch? would anyone know of the location on this model ? I see it has a "T" where the oil sending unit and a 3 term pressure switch screw in.

Thanks,
Ross

 

back in the 80s (on the cars that i know) ford fuel pump relays had a green cover on them. and they were usually under the drivers seat.
Now remember this info is from my car knowledge.
I'd bet you are looking for a green relay but where??
and usually a relay that works anytime works right. I'd say your truck is not triggering it properly.

 

That 3 terminal pressure switch is an oil pressure cut off switch and if it's bad the engine will not start. I would bet that is what your problem is.

 

Ditto. They used to use the oil pressure switch as a way to shut the pump down if the engine stalled for some reason, like a fuel line was cut or started to leak. Or, if the engine lost oil pressure, it would help to save the engine by cutting the fuel.

The key here is "current when cranking". The start position of the key overrides the oil pressure cutoff.

Oh, and to make things a little more complicated, I once had an ignition module go bad in such a way that it would fire when the key was in "start" but not in "run" - it turned out the module on the distributor was bad.

 

Thanks ! that gives me something to get started on! (pun intended!)