Fuel pump priming circuit

Capacitors in the original A9L for the black LX are toast for sure.

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I slapped the donor ecu in and the priming event was correct. Couple of seconds run time of pump and then off. Cranked it over and it fired and ran smooth. I don’t have the SCT chip on the donor ecu yet so I only ran it for 30 seconds or so.

The capacitors in the donor ecu also show signs of slight corrosion at the connections although they haven’t failed yet. Either way I’m not gonna run the donor without replacing the caps. I’ll also replace the caps in the original. That way I’ll have a spare ecu for a quick swap if needed.
 
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I ordered capacitors for both ECU's. Although I already have a soldering iron, it's kinda bulky for this type of work so I ordered another soldering kit more suited to delicate work like this. The new kit includes a solder sucker to help clean things up. I also ordered acrylic conformal coating to put a layer of protection over the works areas when done. I'll post back with results.
 
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Here’s the donor A9L. Is there any way to tell by the numbers what year car it came from?

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E9ZF - 1989 Mustang
E = 1980's
9 = Year number
Z = Vehicle Type (Z = Mustang)
F = General Parts/Electrical and Electronics Division
 
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well, replacing all three capacitors on that ecu did not solve the problem. The light blue/ orange wire is not grounded so thats not it either.. There must be something else wrong with this ecu. Ill use the spare ecu although those capacitors have the beginnings of leakage and corrosion so Ill replace them too. First im gonna install the spare a9l with the tuned sct chip and test drive. If all seems good Ill pull it back out and swap out the capacitors then put it back in and test again.

I also want to get a backup ecu to keep on hand so Ill trade the bad one in on a reman. I have two foxbody cars, one an automatic trans aod and one a manual t5. Id like to get a spare ecu that would work in either car without repinning o2 harness. If i get an a9p, which was originally designed for auto application, can I run it in the manual trans car without repinning o2 harness? The goal is to have a spare that can be slapped into either car on a moments notice without repinning o2
 
I have learned I can run an A9p in a 5sp car without issue. So I wanted to get a reman one and keep it on hand since it could be a spare for either the T5 or the AOD car without having to change either O2 harness.

Crappy thing is, I've also learned that all the parts suppliers list A9P and A9L as "not available" Used on ebay they're running average $250. There's a repair service available for $120 and I may send my A9L out if I cant fix it myself. I did the capacitor change but it still does not work. Gonna double check my soldering work first and look for any other obvious issues. If I have no success, Ill send it out. The service claims they will repair it, or, if its not repairable, they refund your money. I'm guessing that is minus their cost of shipping the bad unit back to you.
 
To follow up on this post I have installed a replacement ECM A9L in my 92. I inspected the capacitors that the vendor had installed and they were a different rating than stock. Stock would have two 47uf 16v and one 10uf 63v.

In past research I had seen it mentioned that you can increase the voltage of these caps but the uf ratings should stay the same. Upon receiving the replacement A9L, I opened the cover to see the work inside before installing the ECM in the car. What I discovered was that all three new caps were 47uf 35v. Since the uf rating had been raised on the one, from 10uf to 47uf, I thought maybe a mistake had been made in the refurbish process of this ECM. So, I contacted the vendor to question them. They told me the change from 10uf to 47uf on the cap in question was intentional. They said Ford had originally under rated this particular capacitor. They said that on some of the ECM's that were returned to Ford for repair, Ford itself was changing the 10uf to 47uf. They ensured me the ECM was ready to go and insisted I would be happy with its performance. It's been working good since I installed it thus far.

Anyway, I wanted to report this to see if any of you have opinions on this change of uf rating on one cap because I've seen it mentioned that the uf rating should not be changed. Again, I was clear in my questioning to the vendor and they insisted what was done is an improvement. There was a thread at Corral where a poster mentioned he had found all three caps in his ECM to be of the 47uf rating too.