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Discussion Starter · #1 ·
i have an 82 Spider with Bosch L-jetronic. got this as a project for me and my son. replaced both fuel pumps, main and fi relay, new ignition switch and been thru the l-jet diagnotistics already and replaced a few things.

Car cranks, but cannot get a spark.

Coil was wired backwards, but have corrected that already.
from another post, here is what i have checked.

When you turn the key to ON, do you get 12v at:
• the fused side of fuse 7 -YES
• the (+) terminal of the coil -YES
• the fused side of fuse 8 -YES
• ignition ECU connector terminal 10, green/black wire to/from Drive relay terminal 15, via connector G121 -YES
• ignition ECU connector terminal 4, violet wire from igniton switch terminal 50, via connector G121 -NO

I have pulled both flywheel sensors and both are clean and undamaged. all other Ljetronic component checks show successful.

Coil has been tested, and shows appropriate spec values on primary and secondary.

Also have swapped ignition ECU for a known good unit, and still same results.

with voltage at coil, i am trying to determine why coil will not fire. how do i test to see if the pulse is being sent to the coil?? etc.

i know we are close here, and likely something simple. HELP!?

Thanks
Tim
 

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I just solved the exact same problem.
Instead of relying on ohms to test your crank position sensors, set your volt meter to a very low setting, like 1.5V and hook your leads like you were testing for ohms on the diagnostic page. When cranking with the starter, you should detect an intermittent signal of inducted voltage produced by the position sender. Mine seemed to ohm OK, but one failed to produce the voltage signal. I replaced and the car started instantly.
 

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• ignition ECU connector terminal 4, violet wire from igniton switch terminal 50, via connector G121 -NO

I also had this issue until someone wrote that the #4 is only hot with the key on.
 

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#4 while cranking?

• ignition ECU connector terminal 4, violet wire from igniton switch terminal 50, via connector G121 -NO

I also had this issue until someone wrote that the #4 is only hot with the key on.
Since the procedure said to test with the key on, perhaps I misspoke and #4 only has voltage while starting. I do remember having to hook up some test leads to allow me to see the meter while in the drivers seat.
 

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Discussion Starter · #6 ·
Alfa spider- no spark yet.

oaky, thanks for all the help from Papajam and responses so far.

i have checked every sensor, and ALL wiring for continuity throughout the car. everything works correctly. replaced TPS that was intermittent, but that was the only gremlin i coudl find.

i am getting a pulse from both flywheel sensors, and voltage at all points it appears it shoudl have, including 12 volts at the coil with key on. however i still dont seem to get any pulse from the coil to the distributor. i have 12volts at + side of coil (between + side of coil and ground) at all times with key on.

i also checked from (-) side of coil to ground, and i get 12 volts there too. however the coil doesnt seem to pulse. shoudlnt the negative side of the coil change voltage while cranking?

help, i know we are close, but need your help still.!!!!

Thanks
Tim
 

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Discussion Starter · #7 ·
update

okay, tested the coil, and by grounding it to a KGG, and breaking that contact, spark is sent thru high tension lead. Coil is Good!

however, the ECU is not sending the 'fire' signal, or breaking the ground.

we tested both crank sensors. and both are putting out very small voltage (like 4-7 millivolts). is that enough to trigger the ECU to fire? sounds like a very small amount of voltage, although one of these is a newer sensore and both seem to sending something! cranking voltage is still at or close to 12 volts so we are getting voltage, and coil is working.

already swapped for an allegedly good ECU, but coudl it be bad? (2 of them?)
Thanks
Tim
 

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Same problem here

Did you get this resolved?

I have an '82 that just shut down on my while driving yesterday, I have performed the same checks as you but I'm stumped.

10.7v while cranking.

Does the drive relay supply power to the fuel pumps while cranking? Mine turns on briefly with the key, then clicks off the fuel pump. It doesn't run any more after that.

Sorry for the hijack, I was about to start a thread on this, but yours is the same issue exactly!
 

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try a new or different rotor

If you haven't tried a different rotor yet, I would. I know it seems implausible, but I've had that resolve problems like yours in the past.
 

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It turned out to be the lower crank position sensor. Troubleshooting with the multimeter produced ambiguous results, but after trying everything else, left no other option. Replaced the sensor and it started instantly.
 
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