Bear with me here as this is a lengthy post. I recently bought a 1991 Formula (5.7 TPI) and the guy I bought it from wasn’t honest about its issue, he said it needed a fuel pump. Fast forward to today the car is in my driveway and after weeks of trial and error, I believe I have no power to the injectors as I’m getting no flash with the noid test light. The previous owner bypassed the Vats and from what I see, has gone through everything trying to chase the issue down. Looks like he pulled the distributor to chase down any issues there, injector plugs have recently been removed/re-installed, new fuel pump etc.. I first changed the chip to one made by Tuned Port Induction specialists but all that did was enable the Vats again. I then ordered a new ecm and installed the original chip but still nothing. The car will crank and if I spray fuel into the plenum it will fire right up. I checked the OHM’s on the injectors and they all read 12 across the board. The relays all seem to be ok, fuel pressure seems good and I don’t see anything out of the ordinary. I’m going on a month now, still no luck and would love some feedback.

 

Have you taken a volt meter to the pink wires on the injector harness? See if you are even getting 12v there.

 

The injectors could have two reasons for not firing, no power or the ECM is not firing them. They should have constant power on the pink wire with ignition on. If there is power that means the ECM isn't pulsing, which would probably be a VATS problem. Changing the chip in the ECM will not re-enable VATS. It's either set or not in the chip. Tuned Performance made me a chip to disable VATS in my 91 TA and that worked perfectly.

 

I checked the fuse panel and with the key 3/4 over I’ve got power. Checking the injector harness I’ve got power at both female ends inside the plug.

 

I checked the female end of the injector plugs and I’ve got hot at both terminals. Regarding the chip, as soon as I put the Vats bypass chip in the security light came on and it wouldn’t crank. I put the original chip in and the security light went off and the car cranks again

 

Let Tuned know, he will make it right if it is a chip problem.

 

The passkey module is what controls the security light. If a bats bypass chip is used the starter enable relay will have to be bypassed. Jumpered or ground the passkey relay control wire. If I did a tune for you and it’s not working please send me a pm or email. I skimmed the thread but didn’t see if you have spark or if you have replaced the icm.

 

Howdy, I did the bypass on the relay when I used that chip but car still didn’t fire

 

A few things to check, injector grounds at the back of the passenger cylinder head. If you have a piggyback try hooking to the memcal but leave out the piggybacks chip. See if you have injector pulse. This would put the ecm in limp home mode.
have you replaced the icm ? You can have spark but still have a bad Icm.