Standalone ECU A610

You beat me to it, I was going to say sounds more like a relay dropping out because of heat. Are relays heat rated as they are just screwed onto that backplate. I get this in my job as it is a common fault which causes intermittent breakdowns. They work but once they have been running for a long time they get too hot it seems like they have lost there heat range and then they just drop out.

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On that logic, the relays would drop out whether they were controlled by the ecu or not... the fuel relay doesn't drop out when a hard 0V return is fitted a la le strap-on, but do when the 0V return is via the darlington in the ecu.

Martin

Yes that has removed that theory, The only other thing I can think of is what happens when the car has a crash there must be some sort of fuel cut off built-in somewhere maybe it is motion and heat sensitive.

....... The only other thing I can think of is what happens when the car has a crash there must be some sort of fuel cut off built-in somewhere maybe it is motion and heat sensitive.

See below :-

The fuel pump relay is controlled by the ECU when the engine starts to turn by cranking or engine running.
The reason this happens in this way is that the ECU uses the crank sensors pulses to firstly trigger the ignition, and also control the circuit to energize the the fuel pump relay.

I have just had another look at the cct diag of the 610 ECU wiring in connection with the fuel pump, and contrary to popular belief, I still believe the fault lies within the ECU ..... rightly or wrongly.
The only thing that will convince me otherwise, is for an owner with a 610 that has this fuel pump fault, to try and locate an owner of a 610 that does not have the fault ...... there are a very few of these, I understand ...... and with their cooperation, arrange to meet and swap the ECU's from Alp to Alp, and see if the fault follows the ECU or the Alp.
I still think that we have a batch of ECU's with possibly a rogue component within that is giving trouble.
One other thing ..... if two members do get together on this, it would be very interesting to compare any numbers that may signify a different batch manufacturing number, or any numbers that may be different.

Martin F ...... I was hop[ng to meet up with you last year in Macon to discuss this, unfortunately you were not able to attend, so an opportunity missed sadly. But I would like to hear of your views on this fault.

[simontaylor]

Could some one with a car displaying the faults, install a manual Fuel pump over-ride switch to provide direct power to the fuel pump relay rather than allow the ECU to control it. If the fault disappears......it could help point to an ECU fault.

Or maybe 2 owners could swap ECUs and see if the fault moves with the ECU, or not?

My 610 didn't have this problem at all, no strap, nothing. Even in the heat at Macon, never missed a beat...after I had an injector overhaul...but that's a different hot running story.
I don't know how it's behaved since Tom has had it, in the intermediate time Clee has had the engine out so the loom will have had a bit of a shake up.
Orbit12 (jamie) bought his 610 at the same time as mine and cured its cutting out by going over the engine loom and removing all high resistance connections. His theory (if I remember correctly) is the 610 ECU, being later than the GTA one, has some kind of cumulative fault counter and cuts the pump when it gets to that point. Turn off and on and you start the counter from zero.
Heat will make the loom less reliable I guess and start to log improbable values.
I guess a scope/logging of the state of the fuel pump control line will tell you if it's a deliberate act of cutting off, or the relay?
Someone on here also said the ecu upgrade makes the engine less lumpy at idle, so there advantages of more modern ecus anyway.
That said my only concern about the strap option is a crash....it really ought to be wired through some kind of safety cut out, plenty available in old fords, and that really would eliminate the only downside of the bodge.
I suspect this fault will keep us all therorising until the value of 610s starts to fall due to the lack of availability of owners....

Here's the wiring diagram 1992 .You can see an antitheft switch to fuel pump relay + remember we also have another computer in the mix controlling this switch.Central control ECU.236,238,104.
Anyway,here's both circuits for ref.

WP_20161220_001.jpg

WP_20161220_002.jpg

You can see an antitheft switch to fuel pump relay

Lee ..... Can you give me the number for the antitheift switch from the circuit please.

John

104

Not sure about the error count reset .I've had it where it's fine for a 2 hr drive,it then cuts,retarts,cuts again and again for half a dozen times then is OK for an hour and then cut again 2 mins from home.....Doesn't then do it again for weeks on end ..Was very hot day ...

104

Thanks Lee ....... Item 104 is actually the ign switch, which incorporates a steering lock switch that makes contact when the ign key is inserted in the lock. All it does is put an earth on pin 26 of the CPU for whatever reason I cannot say except that it has nothing to do with the fuel pump in my opinion.
The ign switch part of 104 takes 12v direct from the battery idolater switch/battery which in turn supplies the voltage for the fuel relay and the Injection Locking relay coils (amongst other things) when the switch is turned to both ign and start solenoid positions.
In order for these two relays to energize, an earth is applied from pin 6 for the fuel relay, and pin 10 for the Injection relay. Both these earths are generated within the ECU.
My understanding is that once the engine starts turning by cranking, pulses are generated by a sensor on the flywheel. These pulses are processed by the ECU which in turn supply the earths via transistor switches to both relays ... I suspect separately, as they come out of two different pins.
If you look at the fuel pump relay circuit, you will see that it is a very simple circuit apart from the controlling earth from within the ECU.
As part of my process of elimination, I did wonder if by fitting an external earth .... as Martin shows in his pic above .... this could be creating an earth for the whole ECU as if there was an earthing problem for the ECU. But I have rejected that as the external earth strap cannot connect to the ECU general earth backwards through the transistor switches.

John

ahaha !! anti theft switch !

I had a mate who's car ( some old thing)would suddenly cut out randomly ...Turns out the weight of his keys.....work,home ,shed,car would sometimes turn off the ignition .

Well mour cooked electrical equipment, looking through under the inlet manifold both knock seniors the outer plastic is all cracked. My auto electrician is coming to do the wireing and I am going to run a new earth from the battery to the engine and a new live from the isolator to the terminal by the oli filter at the rear.

[BIG_MVS]

JohnC - I also tried a "working" A610 ECU in my car from J456 JTP which according to John Law didn't cut out. There was no earth strap fitted when I took it to bits.

In fact I tried 4 A610 ECU's and they all cut out...

The straps the way forward in my case it honestly is. With that baby fitted I have had no cut outs ever at all, none, zero, zilch. If we ever did get to the stage where we thought we had found the answer I would not be able to enjoy the car from fear of it cutting out again. Yes my glass is half empty.

Never had anything but a key ring on my 610 keys....no others. Could this be the magic a610 cut out problem, cut off the dangly or heavy other keys and see if the problem goes away....
Can't be that simple can it?

Nah...nice thought though.