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87 GT w/ 347 problems

SpeedDman360

New Member
Spring I decided to buy a 347 Stroker SB from TRE Performance. I built the block up a tad (Budget build) had it installed by a local Mechanic it ran with the speed Density pcm but barely Cause you all know that speed Density don't play nice with mods. I ended up buying a MAF Conversion kit from fiveology racing (A9P PCM, MAF harness, meter calibrated to my throttle body & injectors, directions on how to rewire the stock harness. ) followed directions Correctly. When I go to turn the key, I don't hear my fuel pump prime and out of Curiosity, I tried to Crank my car and nothing. I have dash Lights (Check Engine &Brights indicator ) but nothing else
Thought I messed up somewhere I decided to get an 89 Harness and run that, same issue
So... I thought the PCM was the issue, I sent that back to Fiveology and got a replacement. We tested it in my friends 90 GT and it worked without issue. Tried to install it in my 87 and same problem: No pump or Crank but all dash lights. The Mechanic put his Scan Tool to it and he said he can't read the PCM...

I'm at a loss for what to do. An ASE certified Mechanic is "Confused as F*ck " And the Local Ford Dealership Service department won't touch it. Any help would be appreciated. What should have been a easy swap is costing me a butt ton of cash...
 

Blown347

Moderator
Staff member
Start with the ignition switch. If there is no fuel pump AND no crank that tells me you aren't getting power to those two things at all. Check the tech sticky with wiring diagrams. That will show you which wires to check. Check the key on power source at the switch. If there's no power when you turn the key then the switch is the problem (10 dollar part) if there is power then you need to check power at the fuel pump. If no power at fuel pump, check the ignition lead on the fuel pump relay. If power at the relay then the relay is bad.

No crank there are a ton of checklists online to follow to trace the problem. But a few places to start, check starter solenoid power on the starter side on crank. If no power, then replace solenoid. If power on starter side, check power at starter. If power to starter and no crank then starter is bad.

A good multi meter that at the minimum can check voltage, resistance and continuity is a must for any electrical work. Foxbody systems are really pretty simple with a good diagram and a good multimeter. Let me know if any of the above helps. My gut tells me ignition switch though.
 

SpeedDman360

New Member
I can go back to Speed Density and it fires up rather crappy though. Right now the 89 Mass Air harness is inside it with the correct pins and it has all the symptoms above
Wouldn't that eliminate the ignition switch being bad?
I have power at the pump relay & inertia switch.
 

Blown347

Moderator
Staff member
Well if that's the case then it has to be a continuity issue with the mass air harness. You will have to trace it down the harness to figure out where power isn't going. There's no reason it shouldn't fire if the harness is installed and pinned properly and nothing is broken.
 

Blown347

Moderator
Staff member
With the mass air harness have you tested power at the starter solenoid and the ignition side (not the continuous side) of the FP relay?
 

Blown347

Moderator
Staff member
Something else, have you checked continuity on the fuel pump relay fusible link and the ECU power relay fusible links? they are both on the starter solenoid, the one for the FP is brown and the one for the ECU power relay is blue.
 

SpeedDman360

New Member
The ecu one...what shade of blue because I have a wire that is light blue that looked burnt I have taped off near the brake master cylinder.

Edit: bought car with that wire exposed so I taped it off.
 

Blown347

Moderator
Staff member
it's a dark blue, but it's probably either greased close to black by now or can be faded light blue as well. fusible links aren't just regular wires, there usually really soft on the outside, it'll only be the end at the solenoid, about 3-4 inches on the end of the wire. The actual wire feeding into the ECU fusible link should be yellow.
 

Blown347

Moderator
Staff member
Here are the diagrams. I'm following them and should find a couple more potential problem areas. but if none of it works out then this will help tremendously in tracking down the problem in the harness. If all else fails a last alternative would be to pull the harness and check continuity on the entire thing. It's always a good idea to do this before a used harness goes in a car (although it is extremely time consuming.)
 

SpeedDman360

New Member
How much of a difference is the between the 89 & 90 gt other than airbag? Worse case scenario, I'll turn my car 87/90 GT...winter project anyone?
 

Blown347

Moderator
Staff member
It shouldn't be much. I couldn't tell you exactly but all the major component wiring should be the same
 
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