Bad Computer?

[bouchermb]

I have an 86 convert manual with a supercharged 347 and have a crank but no start situation. The fuel pump primes continuously, instead of brief 5 secs with key in the "on" position.

There is no injector pulse and no vehicle reference voltage at TP sensor and I went through the checklist provided by jricher before and haven't gotten around to it this time around. The car has been converted to mass air and has a chip on the ecu. Last time I was stupid, throwing parts at it, such as a new tps, MSD box, coil, even a new FP regulator and it ended up being a bad distributor.

My question is what are my options in terms of ECU replacements with the part numbers and does anything special need to be done with the chip if it does end up being a bad computer? The current computer is part # E9ZF12A650AA

Thanks in advance.

[Jack Hidley]

The part number you posted is for the hardware. It doesn't tell much about the strategy that the computer uses. The chip must be compatible with the strategy. For an EEC-IV the catch code is a three digit alphanumeric code. Examples are A9L, A9P, A9S. This code will be somewhere on the EEC-IV. Some strategies are compatible with each other.

I would start by unplugging the chip and see if it starts. The fuel pump continuing to run is a symptom of a bad chip or messed up communications between the chip and EEC-IV over the J3 port.

Also check to make sure that the EEC power relay is not bad. I think it is just to the right of the glove box on your car. Not fun to get to.

[bouchermb]

The part number you posted is for the hardware. It doesn't tell much about the strategy that the computer uses. The chip must be compatible with the strategy. For an EEC-IV the strategy is a three digit alphanumeric code. Examples are A9L, A9P, A9S. This code will be somewhere on the EEC-IV. Some strategies are compatible with each other.

I would start by unplugging the chip and see if it starts. The fuel pump continuing to run is a symptom of a bad chip or messed up communciations between the chip and EEC-IV over the J3 port.

Also check to make sure that the EEC power relay is not bad. I think it is just to the right of the glove box on your car. Not fun to get to.

Great info. to have and I actually have an extra EEC power relay from my last " no start" situation, but was told when I brought it, and another tps sensor, that they were both OK. I might end up having the car towed home and I'll go through everything step by step. The chip worked fine with the ECU up until now and are these just plugged into the top of the ECU?

It's an A9L and was curious what part numbers are replacements that will work.

Thanks again for your help.

[Jack Hidley]

A9L uses a GUFB strategy. Other EEC-IV that also use the GUFB strategy are listed below.

A9M (some of these are GUF1, some are GUFB. I don't know of a way to tell them apart. The ongoing theory is some A9Ms were mislabelled from the factory. I don't know which strategy A9Ms are supposed to be)
A3M
A3M1 (very popular)
A3M2
X3Z

A9S and A9P are both GUF1 strategy, so I don't think they will work with your existing chip.

[bouchermb]

I can't thank you enough for your help and I'll look for an A3M1 and hope/pray this does the trick.

[bouchermb]

Would this one be compatible with my setup?

https://www.ebay.com/itm/93-Mustang-...IAAOSwijhdL7Th

[Jack Hidley]

Just unplug the chip from the J3 port and see if the car starts before doing anything else. If the car starts or at least the fuel pump stops running after 5 seconds, that tells you that either the chip is bad or the J3 port is too dirty. You can clean the port contacts with an eraser.

That EEC should work, but it has no warranty, so I wouldn't buy it.

[bouchermb]

Got it and I’ll give this a shot/stay away from that one one e-bay. After reading more in the listing/seeing the pics, I wasn’t feeling overly confident in it working.

There are others out there with warranties.

Thanks again.

[ZEN50]

Will be following as I have a similar issue with my 86 Capri, no start but cranks with fuel pump running way past the regular prime time.

[bouchermb]

Got it and I’ll give this a shot/stay away from that one one e-bay. After reading more in the listing/seeing the pics, I wasn’t feeling overly confident in it working.

There are others out there with warranties.

Thanks again.

Tried pulling the chip out and the symptoms didn’t change. Any other ideas?

Thanks

[Jack Hidley]

Then something is wrong with the EEC. The most common failure is from the electrolytic capacitors in them drying up and failing. Any person experienced in electronics repair should be able test them and change them as needed. Make sure that they follow proper ESD procedures when doing this.

http://support.moates.net/capacitor-...-ford-a9l-ecm/

[4eyedblind]

You can visibly check the capacitors on the board by opening the EEC. If they are dried out they will have leaked, damaging the traces on the board right below them. There are three capacitors on the board, iirc.

[ZEN50]

Capacitors found on ebay…….
https://www.ebay.com/itm/89-93-Ford-...M/352446543989

[rodupr]

I can confirm that a continuously running fuel pump prime is indeed a bad computer. I had the same problem and swapped out the ECU with a known good one and the problems went away.

[ZEN50]

Just an update on my Capri...….. Pulled the A9P out to look at the capacitors and everything looked good there. Had no power to the injectors, ended up swapping the computer out and she fired right up!

[Zap's 85 GT]

I had an A9L with a bad misfire. Capacitors looked fine but I swapped them for good measure. Worked perfectly after new caps. Looking at the caps is not a good indicator of their well being.

[Jack Hidley]

I'll second that. Most bad electrolytic capacitors will never show any signs of the electrolyte leaking out of them.

[erratic50]

Best suggestion gang — get another ECU while you can, take it indoors, and tuck it away somewhere climate controlled. Hell even if it’s just your sock drawer

[erratic50]

Best suggestion gang — get another ECU while you can, take it indoors, and tuck it away somewhere climate controlled. Hell even if it’s just your sock drawer

[Zap's 85 GT]

Best suggestion gang — get another ECU while you can, take it indoors, and tuck it away somewhere climate controlled. Hell even if it’s just your sock drawer

The A9L that I repaired was in fact NOS. First time it was ever used is when I installed it last year into my car. I even picked up a NOS Ford Motorsports M-12071-H302 Harness and sensor package with it. Climate may play a factor but was not a factor in this instance. Some electronic components simply have a definitive life expectancy. Mass Air computers are now 30 years old. That's a long time for complicated electronics to remain in good order.

[erratic50]

Absolutely it is!