No Start 85

[moto773]

No start car. Traced it down to the fuel pump relay under seat not getting ground controlled by I would assume the computor? Can jump leads, make pump run for prime but does not cut back off after supplying prime with key just in on. Can start engine after manual pump prime with jumper, but pump does not start or come on to maintain running engine, so engine dies. Is there a ground point for computor that someone knows of tied to fuel pump circuit, or is my computor probably sick. And if it is sick, is it simple to upgrade to newer box for the added horsepower. Or, will upgrade work with stock 85 engine. Thanks for any info.

[GAboySVO]

I believe there are two relays that click on when you turn the key to the ryn position. One is the EEC power relay and the other is the fuel pump relay.

Normally, you should here a relay click that sounds like it is coming from under the hood and the fuel relay click that you hear in the cabin followed by a short humming sound of the fuel pump priming the system. If you are not hearing the relay clicks, replace the relays.

I haven't done the swap to the LA3 but from what I read it seemed fairly straight foward and there is plenty of info on the web to assist you. You will need a set of 35 lbs injectors (brown tops) and a manual boost controller to replace the factory controller.

Do a search here to find more info.

Also, reset your inertia switch before you do anything else and see if that makes a difference. A little back ground about your situation before the symptons occured would be helpful.

[moto773]

The cabin relay is the fuel pump relay under seat. That is the one controlled by computor through ground contact. It is what I can manually jump to ground to make fuel pump run. This indicates relay good. Its designed to run for second or two when key is turned on, to "prime" engine. If manually primed the engine will fire but die when prime is consumed. Normally the computor would sense engine turning above cranking speed after releasing switch from start back to on, and turn pump back on as soon as it runs. With engine trying to start and run, I can assume computor has power, but the ground that is required for pump "run" is not making. Inertia swith has been checked and is in a make position. There should be several grounding pts. for computor shown on a wire schematic, just do not have one, and don't want to unwrap whole harness to trace them down. Hoping someone can direct me to those. If they are making good contact, then switching circuits in computor are fried. Thank you for reminding me of inertia switch. I had pushed button, but not checked continuity.

[GAboySVO]

My Haynes manual diagram shows that there are 4 grounds and 3 fuseable links. There is a ground on the fuel pump, battery ground, line off of battery ground to chassis, and the ground for the O2 sensor which is the one mounted to the front of the compressor housing.

My diagram also shows that the EEC relay must be energized first before power flows through the enertia switch then to the fuel pump relay coil.

You should be getting 12 volts on the red w/black stripe wire at the fuel pump relay when the key is turned on. The diagram shows that the orange w/ light blue is hot all the time. The switched line out to the fuel pump is pink w/ black. The tan w/ light green goes to the EEC pin 22.

Hope this helps.

[moto773]

Thank you, exactly what I was searching. I will be at parts store tomorrow to get a haynes. Would not have believed a good diagram would be in it. The tan wire is what is missing function. I will check pin at ecu tomorrow. Hoping a fault between relay and ecu, or one of the ground points you list is corroded. Once again thank you for looking.(Might not find book tomorrow). Gonna be a great day here and am hoping to go scuff a tire or two.

[AT6svo]

Re: No Start 85

Originally posted by moto773
No start car. Traced it down to the fuel pump relay under seat not getting ground controlled by I would assume the computor? Can jump leads, make pump run for prime but does not cut back off after supplying prime with key just in on. Can start engine after manual pump prime with jumper, but pump does not start or come on to maintain running engine, so engine dies. Is there a ground point for computor that someone knows of tied to fuel pump circuit, or is my computor probably sick. And if it is sick, is it simple to upgrade to newer box for the added horsepower. Or, will upgrade work with stock 85 engine. Thanks for any info.

I thought I'd comment on this. While GAboySVO is right on about the relays, keep this in mind. When you insert the key in the ign and turn the kep to the ON position, that activates the FP relay and you'll hear the pump prime. After that initial 1-2 second pump prime the ECM will NOT send the signal to the pump to continue delivery UNLESS it is recieving the signal from the TFI/PIP. The TFI is a known source of failure occuring at random (as well as wire insulation corrosion is fairly high in that area also).

So if you can turn the key and it primes, the relays are not the problem, more likely than not, the TFI is. I'm guessing when you ground out the connection the pump runs continously? The is the same thing that occurs when you ground out the proper terminal at STI connector.

hth,

[moto773]

Okay, no prime either, but what is a PIP/TFI? And I thought I might know something. I can find it though. Thanks.

[Pat_in_L.A.]

Originally posted by moto773
Okay, no prime either, but what is a PIP/TFI? And I thought I might know something. I can find it though. Thanks.

TFI: the module on the outside of the distributor.

PIP: the "hall effect" signal generator inside the distributor.

[AT6svo]

No prime either? Huh?

When you ground out the connection at the FP relay (at least thats what I though you said) the pump would prime, run continiously or do nothing?

And for further definition:

TFI: Thick Film Ignition. As Pat said, the TFI module is the grey "box" on the distributor. It "processes" the Hall effect signal created by the Vane and PIP sensor IN the distributor.

PIP: Profile Ignition Pickup. The PIP sensor basically tells the ECM (via the TFI) where the motor is at in its timing cycle so it knows when to fire the injectors and advance the timing depending on RPM.

If ya really wanna become a guru, like Mike Flemming ('cept he's gotta whole lotta real world knowledge), the book, Ford Fuel Injection by Probst (pretty sure thats his name) is an awesome insight in how the EEC-IV system works.

-mike

[moto773]

Yes when I ground fuel pump relay at the tan lead, it runs continuously. I did check to see if it would run, by letting it prime for a second or two, and then tried starting. It did kick over(fired), but it only took a few revolutions of running before it died from lack of fuel. I took that to mean it didn't start pump once the ecm could've sensed it running. Sooo, I'll check connections at the pip and other thing tomorrow. Maybe there needs to be continuty in that area to set original priming. Gotta go, beepers beeping, work calls. Thanks for continued help. Mike.