Another 3.2 start then dies

[nb6179505]

Did a lot more of research, may be time to admit defeat...

So got a new DME after horrible soldering job left circuit board burned. This was seeking more go and driveability from a SW chip in my 1984 3.2, 993 heat exchangers,2in 2out magnaflow

Starts then dies, tried swapping 4 different DME relays, nothing

If I jump terminal 85b on the dme relay to terminal 30 12v battery power I can acctuate the fuel pump, audibly, and the icv hums...I turn over, it ignites then dies, so I think it moves terminal 87

Fuel delivery issue? I'm thinking factory anti theft is cutting fuel at terminal 86

Any thoughts guys? Otherwise AAA comes Monday and tows it to the shop...ugh

Thanks in advance

Noel

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[nb6179505]

Anyone have any ideas?

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[FrankM_]

If there is a factory alarm, it indeed can cut power to the dme relay. Did you only bridge the fuel pump part or also the dme power part ?

On the dme socket : 30 -> 87 and 30 -> 87b will provide power to the dme, injectors, o2 sensor, fuel pump,... always. So use it only for testing as 30 is always hot and unfused in this case!
Always hot = even when the car is shut down (key out).

But non-start can be so much more.

- ground connections
- no power to ecu or fuel pump (check the above bridges)
- reference sensor signal failing - ecu will not allow engine to start
- spark issues: coil, wiring, plugs, dizzy rotor/cap
- fuel pressure
- CHT sensor not working
- fuel injectors failing/clogged
- large vacuum leaks throwing mixture seriously off
- system voltage / battery power too low


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[gomezoneill]

A very bad air leak? Has it backfired could of blown a hose off somewhere.
How long after starting does it die?

[nb6179505]

Got it guys!

Frank s suggestion on taking a look at the anti theft worked out

Horn wasn't going off but jumped wires on the anti theft harness per older threads, now with ignition key on icv hums and fuel pump primes!

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[gomezoneill]

I know it's overused but AWESOME !

[FrankM_]

Originally Posted by nb6179505

Got it guys!

Frank s suggestion on taking a look at the anti theft worked out

Horn wasn't going off but jumped wires on the anti theft harness per older threads, now with ignition key on icv hums and fuel pump primes!

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Great !
I had the reverse, my dme relay was sticky and kept the icv on/humming even after car shutdown (key out). Had some flat batteries and that’s when I checked the circuits around the relay !


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