Hi guys and gals , my 1991 f150 shutoff yesterday and now it wont start engine cranks over(300-6) but relays arent kicking in . relays are all getting power to the main side but nothing to the activation side with the key cranking. if I wire around the relays I can activate the fuel pumps etc. Not sure were to go next possibly bad Computer ? dont want to spend the 200 dollars on a computer to find out it is something simple.
also tested all fusees and checked the relays they test good. any help would be greatly appreciated.

 

check fuel shutoff switch.

i think on a 91 up by brake pedal or near center of dash.

on 92 up it is behind pass. kick panel.

 

Forgot to mention I checked that it is good also tried a blast of starting fluid no luck there so im assuming there is no spark either thanks for the reply, just noticed i listed it as a 91 it is actually a 92

 

There has been some talk on another thread about the ignition switches in these trucks

 

hmmm never thought to test it. would it allow the starter to crank without allowing the relays to open the fuel pumps ? thanks for the reply 60F100

 

you have a (300-6) and no spark...., my brother had that problem on the work truck .... he changed the modual on the bottom of the distributer (about $100) (and you need to buy a special socket) and it started......

 

joewaldner did it keep the fuel pumps from running also ?

 

no ... the fuel pump still ran ....

 

thats whats strange no fuel pumps no spark but everything else works ,lights ,radio,horn. I'm lost on this one . thanks for the reply

 

if no start with starting fluid than you have a spark problem.

 

pumps arent kicking on at all unless i bypass the relay (relays all tested good) and no spark.

 

if it doesnt pump unless you bypass the relay..... I would imagine the relay if no good

 

Ok checked relays again they function still wont activate when the key is on also no spark I think I might have to buy a computer

 

oops forgot to state the relays work out of the truck when you put them in the truck they dont work tested the pumps by hot wiring them to the battery with a long wire

 

check the connector on the computer.

could be loose or corroded.

go to junkyard and buy a computer that will match yours.

check under power distribution box where relays are, they have been know to corrode and cause problems.