Does the alternator need to send power to the dash to start?

[e30onBBSs]

I swapped the head and it cranks very well but I just took a video of the crank pulley and noticed the alternator belt doesn't spin. A new smaller belt is necessary but would the alternator not spinning cause a no start? I know on some newer cars its like b+ or whatever and it won't work without it. Just a thought. I have spark, fuel at the rail (maybe not at the injectors) and everything is hooked up. Need a buddy to help me check for injector pulse.

Just checked for fuel at the FPR return and when it cranks there is lots of fuel and the car ran well before the swap. Checked spark and it was a nice blue spark. My guess is the injector rail isn't getting power I need to check that later.

Used a screwdriver as a stethoscope and didnt hear any injector ticking

[Ether-D]

I beleive it does not need anything from the alternator. Check to make sure that your CPS and spark pulse connectors aren't switched. Or maybe timing related.

[e30onBBSs]

Spark and fuel wouldn't work if they were wrong no?

Since fuel is going through the rail I think it's either out of time or the rail is broken and not sending power to the injectors

[TobyB]

Alternator shouldn't matter...

If the belt's not turning, has the front engine pulley fallen off?

That'll do it- the ecu's not getting a timing pulse...

also, swapping the 2 connectors for crank sensor and (whatever it is) on the left front
of the head does that, too

thinking with the keyboard,
t



t

[e30onBBSs]

Does the alternator need to send power to the dash to start?

Just in case someone else has this problem this is the diagnoses so far (only had time for cylinder one)
Compression was 125 for cylinder one (seems fine because eta bottom end? Spec was like 140 in the bentley idk for which engine), I have spark, and fuel goes in and out of the rail with good pressure- but no injector pulse and the spark plug does not smell like fuel. So I'm going to test the c191 for power and also power each injector with the 9v alligator clip trick to see if they spray and then rule out injectors.

To test power for the c191 I assume it's positive in each of the banks for the injectors to ground? One bank at a time?

Think I need to delete the c191 =0

[nando]

I don't think you even need to bother testing it, that connector is obviously corroded.

it should have been a sealed connector, but AMP/Tyco hadn't come up with those designs yet when these things were made. you could actually rebuild it with new pins (& seals this time) and it would probably last another 30 years.

[e30onBBSs]

Does the alternator need to send power to the dash to start?

I don't think you even need to bother testing it, that connector is obviously corroded.



it should have been a sealed connector, but AMP/Tyco hadn't come up with those designs yet when these things were made. you could actually rebuild it with new pins (& seals this time) and it would probably last another 30 years.

That's what I concluded once I opened it up and looked at it too. I ordered a deutsch connector like this one and it's going to be good. I am pretty sure it's going to start- power at the injectors is the only thing that's missing



Thanks Nando :)




The deutsch plug was too small for some wires and a general pain in the ass so I said f this and just crimped the wires for the first round and got the car to start!

It ran like poop above idle, only half the injectors were getting power- a poorly crimped crimp. Using butt crimps was really tough after a few were done so I opted for snap connectors and it's great now. Still need to tape the connection but I haven't driven it a lot because the coolant temp sender is broken (gauge jumps to red when grounding the pin).
Lengethened the wires and labeled them