87 mustang wiring
Asked by 72TorinoBrunswickGa Sep 24, 2016 at 11:49 AM about the 1987 Ford Mustang GT
Question type: Maintenance & Repair
We have an 87 mustang 302.
We pulled the engine for over haul and had all of
the wires mark so we believe that we have all back
correct even followed a wiring diagram to verify.
Problem is when we try to start it will turn over but
not fire.
We switched the (fuel pump relay wire) on the (3
prong oil pressure sender) (fuel pump relay/starter
tie in/fuse panel) with the center wire (starter wire
tie in) and fires immediately, but the starter
continues to spin.
Any ideas what might be wrong?
3 Answers
Hard to guess/troubleshoot with so little info - maybe call the shop I work at (Prestige Mustang) and one of the boys can try to talk you through a few scenarios? They have seen it all! Shop hours are m-f 9-6 Sat 9-2 est 770-207-PONY(7669)
I know this question is two years old,but just in case someone has this same/similar question or finds this post through a google search,I thought an answer to this might help them. From the posters wording (confusing as it is) it sounds like the fender mounted starter solenoid was wired incorrectly.The solenoid wiring was different between the 86-91 & 92-95 5.0 Mustangs,because early models used a standard starter while later models used a mini starter. ** This wiring difference must be applied to early models that have upgraded to a mini starter too ** It sounds like the poster connected the O/LB fuel pump relay wire (which should be hot at all times) to the wrong solenoid post,which would have caused the no start issue he had. Therefore this wire must be connected to the same solenoid post that the (+) battery cable is connected to,since every wire on this post will be hot at all times.If its connected to the opposite large solenoid post or the small post,the FP relay wire will only be hot when the key is turned to the start/ crank position and as soon as its released to the run position,the wire will go to ground and the fuel pump will not run.This wire must remain hot at all times,regardless of key position. It sounds like the poster had this wire on the wrong post (on his 1st attempt) & he had the starter cable/wire on the right post (on his 1st attempt) & upon his 2nd attempt placed the fp relay wire on the right post,but placed the starter cable/wire on the wrong post. If the relay wire would've been moved and the starter wire would've been left where it was at,the engine would've started and ran and the starter would've shutoff like it was supposed to do.This site format only allows for one photo,so Im posting a diagram for the 86-91 or standard starter solenoid wiring in this post and a diagram for the 92-95 or mini starter solenoid wiring in a 2nd post.Use the appropriate diagram for your starter type,regardless of year model. (Standard Starter Solenoid Wiring Dia)
