EFI - no start, need help!

[stangman16]

I've got a '66 Mustang EFI that I've tried two harnesses on and it has a new ECM. I have gone through jrichkers no-start checklist and I do have spark, but the injectors are NOT firing, as indicated by a noid light.

I have the 12v to the red wires on the injectors when the car is on the RUN position, but when it is in the START position the voltage drops to Zero.

TPS reads 1.0v with the veh in the RUN position, and in the START/cranking it reads Zero also.

I obviously have something hooked up wrong for there to be no power to both these in the START / cranking positions...

where did I foul up ?

 

[HISSIN50]

Assuming power comes back online after you release the key (from cranking to run): It sounds like a feed off the ignition switch is wired through the starter interlock (like how the radio and other circuits shut off while cranking so as to provide max power for the starter). Resource this feed so it's hot during cranking and in the run position and things might function better.

Good luck.

 

[stangman16]

Got the injectors to fire now & the TPS to have a reading while cranking, didn't have power to the TFI for one of the red wires there.

I had my dad check the color of the spark and he said it is yellow not a fat blue color as it should be - what could cause a yellow spark? The coil I have is practically brand new. The car has never run with the EFI and it's a Ford Racing High Energy coil. I have tried to start this car about 50 times maybe in this last year.

 

[jrichker]

Got the injectors to fire now & the TPS to have a reading while cranking, didn't have power to the TFI for one of the red wires there.

I had my dad check the color of the spark and he said it is yellow not a fat blue color as it should be - what could cause a yellow spark? The coil I have is practically brand new. The car has never run with the EFI and it's a Ford Racing High Energy coil. I have tried to start this car about 50 times maybe in this last year.

The red/blue wire gets power from the starter - remember the push on stud on the starter solenoid? That's where it gets power from for a start cycle.

The red/green wire gets power from the same red/green wire on the ignition coil or ignition switch

Diagram courtesy of Tmoss & Stang&2birds

See the following diagram for EFI wiring on a stock 87-90 Mustang - notice the red/green wire going to the ignition coil.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel pump, alternator, ignition & A/C wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Computer, actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Fuse panel layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

 

[stangman16]

The red/blue wire gets power from the starter - remember the push on stud on the starter solenoid? That's where it gets power from for a start cycle.

The red/green wire gets power from the same red/green wire on the ignition coil or ignition switch


See the following diagram for EFI wiring on a stock 87-90 Mustang - notice the red/green wire going to the ignition coil.

I just double-checked, and I do have the two red/green and red/blue wires hooked up as stated. I'm getting a fat yellow spark from coil and from distributor.

Could a bad chassis to engine ground cause a weak spark?

 

[HISSIN50]

In my experience it's a weak battery or bad coil that causes an off color spark.

Regarding the thought about the motor ground: You can throw a jumper cable from the engine to a grounding point on the chassis, but it would not be my first choice if your starter is able to crank the engine over just fine.

Jrichker very well might have differing thoughts on that.

Good luck.

 

[stangman16]

Could be the battery, I know I have to charge it up everyday after I try and start it. I've been working on this EFI conversion for a little over a year off and on, and it's not run once on its own yet.

Could the yellow spark keep the engine from running now that the injectors are firing?

I'm going to go down and have the battery tested at my friends oil change shop...

 

[jrichker]

Yes, I have had that happen to me.

 

[stangman16]

I picked up a new battery, the one I had was at 80 CCA but still had the 12v. Placed in the new one, and the spark is still yellow. Guess that means I need to go get another coil ?