1990 Spider Motronic ECU 261 200 124 - Alfa Romeo Bulletin Board & Forums
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post #1 of 16 (permalink) Old 03-18-2019, 01:46 PM Thread Starter
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1990 Spider Motronic ECU 261 200 124

Trying to get this spider back to life after previous owner let it sit outside for 12 years.

Got it to run but have to apply separate power to fuel pumps. Thought is was in the relays but not so. The fuel pump relay gets power from the aux relay and the Motronic relay but the coil is never energized. It appears to get that circuit completion from pin 20 on the Motronic ECU. Terminal 85 of the relay goes to pin 20 of the ECU harness. If I pull the relay and jump across terminals 87 and 86 or 87 and 30, the fuel pumps run.

Is this only model ECU that works in these cars?

Does anyone in the Atlanta Georgia area have one that I can plug in to test my theory before sinking a bunch of money in a rebuild?

Any other ideas?

Thanks
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post #2 of 16 (permalink) Old 03-19-2019, 01:04 AM
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Originally Posted by pantera928 View Post
Is this only model ECU that works in these cars?
yes, 'fraid so, it needs to be the Bosch # 261 200 124

Greg,
one little thought, are you certain the 4 relays are in their correct positions? Perhaps a PO took them all out whilst troubleshooting and mixed one up...

Check the wiring colors in the diagram to each relay socket to confirm correct positions.

you are getting direct battery power in at pin #30 of BOTH the motronic diode relay and the aux. motronic relay...correct?
Check also the 12v power post (G137) on the side of the ECU frame is tight and secure.

I'd have loaned you my good spare ECU to try, except I am about 4500 miles away!
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Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.

Last edited by spiderserie4; 03-19-2019 at 07:03 AM.
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post #3 of 16 (permalink) Old 03-19-2019, 08:57 AM Thread Starter
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Three of the 4 relays are the same type. One is a special relay with a stripe for the ECU.

12 VDC is present and I also checked the wire continuity from pin 20 of the Motronic to 85 on the fuel pump relay.

Thanks
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post #4 of 16 (permalink) Old 03-20-2019, 10:23 AM
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Three of the 4 relays are the same type. One is a special relay with a stripe for the ECU.
yes, but is the red stripe one in the correct socket?

It is the only relay socket that has a 3 thickish reds going to it (and a solid orange)
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Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #5 of 16 (permalink) Old 03-20-2019, 01:33 PM Thread Starter
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I think it is but the interesting thing is that on 2 different wiring diagrams I have seen, the order of the 4 relays is different. I will check the wiring later today.
Did I mention that the tachometer doesnt ever move either. Been meaning to check that out also
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post #6 of 16 (permalink) Old 03-20-2019, 02:03 PM
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Originally Posted by pantera928 View Post
I think it is but the interesting thing is that on 2 different wiring diagrams I have seen, the order of the 4 relays is different. I will check the wiring later today.
Did I mention that the tachometer doesnt ever move either. Been meaning to check that out also
The relays can be in different locations, seen that often!...depends how the guy at the factory was feeling that day

when you say the tach needle does not move...you mean even when you got it to run? It should jump (very slightly) even when you crank the starter.

does your S3.5 have this connector like the S4 (top one, G133b), if so check its connections. check also fuse #7 & #8 for speedo and tach.
https://www.alfabb.com/bb/forums/7134426-post3.html

Otherwise you probably need to remove the instrument cluster and have it sent out for refurb.

But lets try get it started first
btw. the motronic needs min. 11.5V 'whilst cranking' to wake the computor...I presume that's the case here?

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #7 of 16 (permalink) Old 03-20-2019, 06:39 PM Thread Starter
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Fuses all good. No time yet to check the connector for the tach.

The special relay actually has a different colored socket to plug it into so hard to mess up unless color blind.

Replaced the faulty fuel regulator today and the car started and ran well with the fuel pump being fed from the battery.
Tried removing the ECU and then grounding pin 20 on the connector and the pumps picked up like they should.

Replaced oil sending unit and now see great oil pressure.
Not running it very long until I go through the cooling system. Hoses look ready to pop any time.

FYI, I disconnected something and then tried the fault code reader and it gave me what I expected so somethings are working.
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post #8 of 16 (permalink) Old 03-20-2019, 07:18 PM
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You need to check that the relays are in the right terminals blocks by the wiring color going to the blocks. When the cars were built the blocks were not always put in the places shown in the manual.

Its all about the wire color.

1969 1750 Spider Veloce w/dual webers, 1969 1750 Berlina, 1971 1750 Spider Veloce w/ dual webers, 1985 Spider Veloce 23,000 orig. miles, {Two} 1986 Spider Veloces, 1987 Spider Veloce bought new, 1988 Quadrifoglio, 1991 164S, Plus several more. I think they are breeding.
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post #9 of 16 (permalink) Old 03-21-2019, 01:57 AM
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OK so car started and ran well with new FPR and the pumps directly powered...That's already something positive!
so somewhere along the line power is not getting to the pumps.

check voltage at pin #87 of fuel relay socket (orange/black and pink/white wires) whilst cranking

check for continuity between fuel relay pin# 87 via connection G107 and the fuel pump.

This shows G107 on a 1990:
https://www.alfabb.com/bb/forums/961434-post12.html

lastly remove and visually check your fuel relay and the other 2 identical ones have correct pin designations, not only that they have pins 30/85/86 but also that the two 87 pins are parallel to one another.

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #10 of 16 (permalink) Old 03-21-2019, 06:23 AM Thread Starter
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Dom
All good advice and appreciated but mostly already done.

The Aux relay and the Motronic relay are getting power from the battery on terminal 30.

The fuel pump relay is getting power on term 30 from term 87 on the aux relay

The fuel pump relay is also getting power on term 86 from term 87 on the Motronic relay.

If you ground term 85 on the fuel pump relay, it is energized and the fuel pumps come on.

If you jump terminal 30 to 87 on the fuel pump relay, the pumps will run.

All that proves the wiring to the pumps is good.

FYI, if you rev up the motor the VVT relay engages and disengages when you back off.

Now you mentioned checking power at term87 ofthe fuel pump relay while cranking. Why is that? it should have power once the key is turned on without cranking to prime the system.
That is the only thing you mentioned that I have not done.
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post #11 of 16 (permalink) Old 03-21-2019, 06:39 AM
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Motronic doesn’t prime the system. Fuel pumps only start up when cranking.

If you’re expecting the pumps to come on when you first turn on the ignition, that’s not what happens.
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1963 Giulia Spider (1750 engine)
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post #12 of 16 (permalink) Old 03-21-2019, 06:45 AM
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Now you mentioned checking power at term87 ofthe fuel pump relay while cranking. Why is that? it should have power once the key is turned on without cranking to prime the system.
That is the only thing you mentioned that I have not done.
....it was something Papajam recommended doing on a similar thread I was reading.

the solution in that thread turned out to be another problem, an incorrect fuel relay - the relay looked correct, but the two #87 pins were not in the same positions (parallel) as they should be.

edit: ok so you have tested continuity on the pink/white from relay socket to pumps it seems.

I really am suspecting your fuel relay, because if you jumped the pins and the pumps worked, then the relay is (at least) suspect. Swop it out with your old horn relay, just for fun
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Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.

Last edited by spiderserie4; 03-21-2019 at 06:49 AM.
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post #13 of 16 (permalink) Old 03-21-2019, 06:53 AM Thread Starter
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Okay Gubi and spiderserie4, I am gobsmacked! An old dog can learn new tricks.

Following Dom's advice, I tried cranking the car and watching term 87 of the fuel relay for power and it did indeed have power and the car started right up and ran fine. This is what Gubi just confirmed as well.

This is quite different from the S3 series cars and never in all my years have I seen an electronic injection that did not at least have something like a 3 second prime timer or have the pumps run continuously with the key on.

So, I have been chasing my tail over nothing. Guess it is time to change out the thermostat and cooling hoses and clutch hydraulics and see how this thing drives. But not today. It is raining.

At least I did not send the ECU out for an unneeded repair for a few hundred USD. $$ I might look to buy a spare now that I saved that money.

Thanks for all the advice and patience.

Greg
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post #14 of 16 (permalink) Old 03-21-2019, 07:16 AM Thread Starter
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Dom
Did I mention that the horn doesn't work either! LOL. No bets on that relay.
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post #15 of 16 (permalink) Old 03-21-2019, 12:47 PM
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Hi Greg,
great its running!

However, I haven't quite understood what exactly you did to make it run again...
you said: "I tried cranking the car and watching term 87 of the fuel relay for power and it did indeed have power and the car started right up and ran fine"

did you swop out a relay, find a bad connection...something else?

Oh, and if you want to test the horn relay (top row, far left in the drop down fuse box), just put the fuel relay or another of those 3 identical ones from under the rear parcel shelf in its place and see if the horn works....if not, then check the ground wire that enters the steering box, up through the steering shaft to the horn push, there is a connector and this might have come loose behind the steering wheel.

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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