i scored a smoking deal on an 86 with a 302, 6" kit and 36" TSL's but im having a problem getting it to fire. the fuel pumps are both working and wired to a toggle switch. i have great spark and it set pretty much where it needs to be to atleast start. i think i have in narrowed down to the injectors are not firing. i have fuel pressure all the way to the schader valve in the fuel rail but when i pulled a plug to check they are not wet and i can get it to fire on starting fluid. is there anyone out there that can offer me any help or ideas before get really pissed and put on a holley. i coudnt pass it up for $500 but i am not very familiar with the Ford EFI. thanks.

 

Why are the pumps wired to a toggle switch? If they will not start/run on their own, you have a problem elsewhere. The computer must see ignition pulses in order for the pumps to start.

It sounds as if there was a problem no one could fix, and they patched it with the switches. jd

 

they were wired that way because the fuel pump relay was bad but has since been replaced and they just stayed wired that way.

 

Heres how it works.

Ignition on - EEC power relay closes supplying power to the pump relay and sensors.
Pin 22 of of the computer momentarily grounds closing the pump relay for a couple seconds priming the system, then it removes the ground waiting for ignition pulses from the distributor.

Starter engages spinning the engine supplying ignition pulses to the computer, grounding pin 22 once more supplying a steady supply of fuel to the injectors.

Pin 58 of the computer pulse grounds the injectors supplying fuel to the engine. The injectors are supplied by 12vdc. At ignition on with the engine not running/turning over, you should have 12vdc on both wires of the injectors.

I use a test light, and spin the engine over. If the injectors are working, you can see the light slightly dim as the injectors fire. You can also use what is called a "noid" light. This will tell you if the injectors are working. These are kind of expensive as you have to buy them in a set. Maybe you local auto parts have loaners.

However, the first thing I would do is get rid of the switches, and get the system working as designed. This kind of "rigging" will sometimes confuse the computer causing other problems. jd

 

You can get a noid light for about $10 @ AutoZone. Check all of the ECM and body grounds.

 

81TREKKER, I'm having the same problem with my 87 f350 351w, I switched from carb to efi motor will fire on starter fluid, but fuel pump will not run (i jumped to 12v bat to get it running) and fuel injectors will not fire. I'm going to work on the problem during holidays. Let me know if you come up with anything.

Could someone tell me where the pwr relay is?

philbax

 

ECM relay should be near the core support on the passenger side I believe on the 87 model. If not there, it should be under a cover near the master cylinder. It will say EEC and is grey. The Fuel pump relay is green.

 

If your truck came out with a carb I do not think you have an ECU Power relay. You should have installed one when you changed over to EFI. You will also need an ECU Computer and should get a wiring harness off an 87 EFI truck.

 

My replacement efi motor came from a 89 bronco, I've replaced all cab wiring and engine compartment wiring. The only relays I can find are on driver side by air filter, they are not labled one is green the other one is brown. I have nothing labled eec relay.I have one conn. labeled eec test

Thanks


Philbax

 

The brown one is the ECU (EEC/PCM) Power relay and the green one is the fuel pump relay.

The EEC test plug.


There should also be a one-wire plug near this one that runs (starts) the EEC system test (for pulling codes).
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Hey thanks, are there any other relays that supply voltage to the fuel system? I was going thru posts and came across somthing about a bk/grn wire in round connector located by batt should be connected to batt ground, this wire provides ground to the eec pin 40 and 60 I do remember this connector during swap just did'nt know where to con it.

 

It goes to Negative Post of the battery. The Fuel Pump Relay activation coil is grounded through the computer and the computer is ground through this wire to the Negative post of the battery by way of pin 40 & 60.


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Thanks for the help! I really appreciate all the helpful tips that are on this site and for the experienced people willing to help out. I think that wire not being grounded is my problem (or one of my problems) I'll check first thing in the morning. Have a great nite and holiday