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Discussion Starter #1
Hmmm... Just as up in Calgary, the Alfetta gremlin has struck in San Francisco, and I'm looking for advice.

Situation: My totally reliable (since I bought it in '93) '84 GTV6 with 132k on the odo quit running, a sudden cutout as I was driving it home in a pouring rain a couple of weeks ago. It started right back up, ran for a minute or so and quit again. And restarted. And died, and restarted, etc. I made my way toward home in this fashion until I got to the start of the freeway part of the journey where I called for the tow truck. After it came off the hook, I fired it up and drove it into the garage. A friend suggested it might be the (original) coil, so I replaced it and no change.

It doesn't matter whether it's running at high or low rpm, idling in the garage or under load accelerating uphill. After a minute or two it just quits. I can hear the fuel pump running after it quits, so I'm pretty sure it's not the inertia switch or the ignition switch (which I replaced about 10k miles ago anyway).

I'll take a look at the Hall effect connection, but doubt that the problem is the unit itself. I had a BMW motorcycle (an '82 R100) which had a Hall effect unit failure (pretty common for those bikes) and the failure was total.

BTW, where IS the ignition control module?

Thanks!
John
 

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Watch the tachometer the next time it quits when you are driving it. If the needle immediately drops to zero then you lost something on the low voltage part of the ignition. If the needle follows the engine rpm as it slows, then your problem is either in the high voltage side of the ignition or in the fuel supply/FI side.
 

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At the risk of sounding like the cop who immediately suspects the husband when the wifey croaks mysteriously, it would seem rain (water) is the key causal effect here. I'd pull the panel on the passenger side footwell and inspect the ECU and connections. Drop the fuse-box and inspect there too.
 

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Almost sounds like a dodgy fuse that once heats up breaks the circuit.
Well worth checking all fuses regularly, and not just a quick visual, i take each one out and have good look over it.
 

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There are two main methods of troubleshooting. One is to make an inspired guess as to the cause of the problem and swap out the suspected component. The other method is to make tests and observations and use them, along with your knowledge of the system to logically deduce the cause of the problem. The first method can be very effective if you have seen the problem many times before and you can play the percentages. The second method is usually the best for problems that you have not seen before or have seen only occasionally. I have been a maintenance engineer for over 40 years and I use both methods.
 

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I had a similar problem with my 86 GTV6. Problem turned out to be the airflow sensor unit. I found it by substitution. I opened the top and found moisture in the unit.

Good Luck!
 

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Discussion Starter #8
Thanks, guys! Lots to look at. I'm not sure what the tach was doing when it quit while driving-- a couple of years ago the tach started sticking and was stuck at 1800 rpm when the trouble started a couple of weeks ago. Dunno whether anyone else has had this happen:



Yep, the needle just started curling until it made contact with the tach face. I took it apart, cut off the curly bit and epoxied a bit of toothpick to the back of the stub. Works great now and tomorrow I'll run it around the block and see what happens. I'll check water and the contacts tonight.

Thanks!
 

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Apparently the bending needle problem is very common, luckily my car hasn't had that issue. There is another thread here on the BB where someone used some model train part (I think) to replace the needle and it looked great.

You've got a long list of things to check, in addition probably worthwhile to check the grounds while you are in there. When we had the hall sensor fail it killed the engine and let us restart a number of times before it died completely. In your case I also suspect the rain might have had something to do with it. As FSM72GTV says, check for moisture in all the wrong places.

Good luck.

Kevin
 

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I had a similar problem with my Milano, and it turned out to be a corroded coolant temp sensor plug. On L-Jet, the ECU requires this sensor to run.

good luck in your search
 

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Discussion Starter #11
I checked the ignition connections, no water to be seen, even under the dist. cap and ran it around the block.

Sure enough, when it quit at about 2500 rpm in 2nd gear, the tach dropped to zero while the car was still moving in gear.

Alfaparticle (as a high school chem teacher I really dig that name), it looks like I'm into method #2...

So it looks like the 12v supply into the ignition system is stopping. Possible spots for this break to occur? Oxidation on the ends of the related fuse? Would high resistance lead to a temp increase at that spot which breaks the circuit, only to cool and restore continuity-- if that's the case, shouldn't the ignition cut back in and out as the temp goes up and down as it goes on and off? Ignition switch gremlins? As you know, you have to turn everything off and remove the key before switching back on again, could this action 'reset' the failure. Are there relays involved in the ignition circuit? I don't have a wiring diagram for this car. I've got the Milano manual- are they similar enough for this to help?

Hmmmm...

Back to the garage!
 

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I have been in the Nuke business for 40+ years - hence the name.

So you are losing the ignition. The module under the coil has a bad reputation, although I have not had one fail. Could also be a flakey connection from the hall effect sensor in the dizzy or maybe the hall effect itself. It would be cool if you could borrow known good ones and swap them out.

Does anyone know if disconnecting the coolant temperature sender cuts out the ignition or just the FI?
 

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The only time my GTV6 left me stranded was when the Spark box went bad, but it was dead with no recovery. You might also take a look at the combo relay.
 
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