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Discussion Starter #1
Hi all,

I have an '83 S3 spider for about 15 years now, but it's taken a back seat to life for the last 6-7. I moved it out of the garage last October (in Houston), and now I'm about 10 hours into diagnosing a no-start that popped up last weekend. Why do I park it for 4 months? Why do I do anything stupid?

Last weekend I couldn't get it to fire at all. This weekend the cold start system is mysteriously working, but I can't get it to stay running, because the drive relay won't latch after start. I can hold it closed with my finger (I cracked it open long ago to see what was in there), and it will stay running. The main relay makes a loud click, so I think that's okay (is this just a normal relay, or is there something special about it?). The car runs if I hold the drive relay closed anyway, so I don't think there's a problem with the ignition system.

I've done a lot of the things on the L-jetronic checklist. Maybe not everything, but a lot. Flywheel sensors fine. Lubed up a lot of grounds (none seemed too bad). Have checked a lot of things.

About me: trained as a mechanical engineer, worked at Yazaki as a wire harness engineer for 2 years, lifelong car tinkerer, but usually in the "just enough to hang myself" category.

The tach started getting jumpy months ago, and now it doesn't move at all.

I CANNOT get the happy, reassuring main fuel pump prime sequence to happen with key-on. I know that sound well; I hear it in my dreams. I can't get it to happen now. So I start, will run 3-5 seconds off cold-start, and die, unless I pinch the tachy/drive relay contacts closed, in which case it will stay running.

I have checked continuity all the way from drive relay 31 (top left of the connector as depicted by the case which reads p/n 0 028 023 001, I think 31b in the book?) to white on the tach gauge to white on the coil (4 leads on driver side, one black/green on pass is that right)?

I removed the inertia sensor and jumped last year, but I didn't need to. It was okay. Anyway, it's jumped now.

Have continuity tested every fuse I can think of. I can twist the fuse box and cause things to go out of contact (like the flasher), which is worrisome, but not related. Just some of that charming antiquated engineering.

Oh, and BOTH fuel pumps were seized. I took each out, hammered with some compressed air, soaked in the ultrasonic cleaner (even ran them submersed, which seems really dangerous, but it's an old RC motor cleaning trick I learned and somehow it works okay - at least it didn't pop my power supply), and they're both running I gather. Maybe not the best pumps in the world, but they're working. This E10 is a scourge to these cars that don't get frequent use.

Anyway, appreciate anything thoughts. I hesitate to but the $89 drive relay, because I'm not sure that's the problem. I see no evidence the smoke was let out of it.

TIA,

Matt
 

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The drive relay needs to get a tachymetric signal via a sense wire on the coil to 'know' the engine is running. The jumpy tachometer might also be a clue that the connections at the coil are iffy. Try cleaning those. The sense wire is either white or yellow (I forget which) and it runs inside a shield wrap (like a cable TV wire). The shielding wrap is grounded so check that, too.

If all that checks out OK I think you are left with a faulty drive relay. There is a bypass circuit that sends power to the fuel pumps during cranking to ensure fuel is delivered for starting. Once the engine starts & the key is released to the run position the drive relay is supposed to take over keeping the fuel pumps operating. Bypassing the drive relay could be a safety hazard - in the event of an accident the fuel pumps would remain powered on even if the engine stalled.
 

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Discussion Starter #3
Thanks. I did hit the 4 white wires on the coil with a steel brush and dielectric grease. I saw the shielding on one of the flywheel sensors. I thought it was a horrendous fray at first, but then I realized it was an EMI shield. It still appears to be connected, although I suppose I could hit it with a continuity test.

Do the coils ever fail? The tach going from jumpy to dead seems like a clue, but I can't decode the darn wire diagrams well enough (and I used to draw the things). There's a lot left unsaid in the service manual. I'll try tracing back from the tach to see if I can get to some weak-point that could be shared by the drive relay and the tach.

Probably have to buy a drive relay, though. I suppose it may be the problem. Or I'll go guerrilla and wire my own fuel pump relay for the big pump, as it seems to run fine once that's going.
 

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I can't decode the darn wire diagrams well enough (and I used to draw the things). There's a lot left unsaid in the service manual.
Check your 'conversations' (aka Private Message) - click on your mini avatar in the top right corner of the page.
 

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Discussion Starter #5
Note to myself - I've checked all the wires per PapaJam's notorious post #31, including even putting a dwell meter on 1 (31b on some tachymetric signal input). I'm getting a tach signal at 1/31b. I ordered a drive relay from Centerline Int'l. Also found one for sale on eBay for a few dollars less, but I guess keeping Centerline in business is good for US Alfas. I think I'll let it alone and see if the relay does the trick.

I am still stumped as to why I don't get the pump-on sequence when I key on. I guess possibly because the relay is broken!
 

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Discussion Starter #6
Sure enough, it was the drive (tachymetric) relay. I got the replacement from Centerline, and it fired right up. Upside is it forced me to ultrasonic clean both pump, and they're both running now. I'm not sure I ever hear the boost pump run before.
 

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Discussion Starter #8
Quick follow-up here. The relay from Centerline is not the original Bosch relay, and instead of running the pumps for 10 seconds with key-on, it runs them constantly with key-on. So if you own an Alfa that has constant-on pumps with key-on, it could have one of these aftermarket relays. Or it could be jury-rigged (which is where I was going to go if the drive relay didn't work). Wiring up fuel pumps isn't all that hard in a race-car, but can lose some of the safety built into it (e.g., killing the pumps when the tach signal disappears, which would theoretically be one way to turn off the pumps if the car were in an accident). Along those lines I'm actually going to put my inertia sense BACK IN. Why not? Was working find before I removed it.
 

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Quick follow-up here. The relay from Centerline is not the original Bosch relay, and instead of running the pumps for 10 seconds with key-on, it runs them constantly with key-on. So if you own an Alfa that has constant-on pumps with key-on, it could have one of these aftermarket relays. Or it could be jury-rigged (which is where I was going to go if the drive relay didn't work). Wiring up fuel pumps isn't all that hard in a race-car, but can lose some of the safety built into it (e.g., killing the pumps when the tach signal disappears, which would theoretically be one way to turn off the pumps if the car were in an accident). Along those lines I'm actually going to put my inertia sense BACK IN. Why not? Was working find before I removed it.
yes, Centerline doesn't deliver the orig. Bosch.
Till not too long ago they photographed the expensice Bosch on their site, and then sent out the much cheaper KAE
KAE relay is one of those that "could" let the pumps run all the time with KO...I say "could" because some people have fitted a KAE that does actually shut off after the few seconds with KO

at least now they photograph an aftermarket no name relay.
although still advertising , "Relay may be Bosch or good quality aftermarket depending on availability", you can bet it'll be a KAE (or similar), and the KAE 3.304.500 that is out there for like 25 bucks.

Anyway glad it is running again!
 

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Discussion Starter #10
Interesting. I don't have any problem with running all the time with KO. It will kill the battery rather quick I suppose. If you're not going to drive-ins (we're not anymore), it's not such a big issue. If it ever becomes an issue I'll wire up a hidden toggle. Great theft deterrent as well. Hmm. Maybe I should just do that while I have it apart. Good idea! Maybe there's an accessory key position so even the drive-in isn't an issue. Been so long since I drove it I can't remember.

I have terminal push-out with the main relay. I bent the little tab up but no click. The plastic must be gone. Little time bomb right there. Tempted to wire in a new relay connector.

The main relay seems like just your garden relay, but when I swapped in a super China relay I got the weirdest chatter from the fuel injectors with KO before start. So I put the ancient Bosch one back in and it's working fine. Do you think the metal case on the Bosch has anything to do with shielding against field effects, or was that just state of the art back then?
 

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doubt whether a relay is metal or plastic has any influence on anything.
the chatter was probably just a cheaply manufactured item gone nuts:)
 
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