EMan 928

First time tried to start from winter storage. Crank but will not start.

Checked for spark with timing light. There is spark
Have fuel pressure and can hear pump when cranking
Car will start with starter fluid, then dies
Swapped LH and that didn't solve problem
replaced fuel pump relay and swapped LH relay, didn't help

Worked fine before putting into storage.

Other than Crank sensor, anything else to check? Would the sensor just die like that?

Hilton

Are you sure the pump noise you're hearing is it actually running?

Fuel is your problem - crank sensor would kill spark.

Rather than listening to the fuel pump while cranking, make a jumper lead for the fuel pump relay and jump pins 30 to 87 (see Tony's page for pics in an '87 S4 - http://members.rennlist.com/v1uhoh/jumping.htm).

Then go listen to the fuel pump with the rear cover off. If its humming but not whirring, try tapping the pump lightly with a small hammer. Your '87 has no in-tank pump, just a strainer, so if the pump's jammed, odds are you need a new pump.

If the pump is definitely working, then use a noid light or similar to check there's a pulse at the injectors.

Have you checked for mice nests around/under the airbox? The injector harness is attached to the ground points under the airbox, so rodents nesting in the V under the intake might do damage there.

John Speake

How did you test for fuel pressure ?

AO

Hey guys... I'm resurfacing for a bit to help Eric out on this car.

I've changed the CPS.\, but it still refuses to run.

The fuel pump will not run unless jumpered, but even then it will not fire. Spark is confirmed.

Clearly the injectors are not firing, but I cannot tell why. I have a jumper on the FP relay and it whirs away and we put a fuel pressure gage on and it has pressure. I want to jumper the LH and EZK relays. Do I just connect 30 to 87, right? Been way too long...

The tach needle didn't move, so I will investigate W11 (I think).

I had another thought. What about the factory alarm? Is there a way to make sure that is disabled?

I'll be diving into this again tomorrow. So any help today would be greatly appreciated.

Mrmerlin

spray the front and back of the CE panel with deoxit after you have removed the fuses and relays.
Spray the 14 pin connector under the hood and clean the battery connections and ground strap,
and the ground under the rear quarter liner, and the grounds in the spare tire well
I think you have a corrosion issue here for the no start, so do the simple things first

AO

Thanks Stan. I'll give it a whirl.

John Speake

You should get a 12v square wave at pin 1 of the LH ECU connector while cranking. This signal comes from the EZK ECU.

It's safer to use a known good 53 relay to substitute for suspect LH relay. If you have spark then there's no need to swap the EZK relay.

Have you a spare LH ECU to can use for testing ?

worf928

Obvious questions: condition of battery? Are you sure that the second LH actually works?

From the symptoms, this is an LH power or ground issue. Either the LH has no or low-voltage power, or no ground, or it can't switch the ground for current sunk to one or more of the chassis grounds, or It's Dead Jim.

Here's what I would be looking for: LH harness damage at block ground points, dead LH, dead relays.

Tools of choice are a noid light, multi-meter and Mark I Eyeball...

... and the LH/EZK troubleshooting guide on the CDs.

AO

Thanks guys. I have two spare LH ECUs. I will try checking grounds and look for square wave now that I have a digital multi meter with me.

Battery is good. Also brought noid lights.

AO

It's alive!

Wow! What a journey though.

We checked to make sure the block was grounded. We jumpered the LH relay and installed a noid light. Cranked... nothing.

We checked for a square wave on pin 1 of the LH, we saw some activity, so we decided it was probably good. When I went to plug the LH back in, one of the guys saw the noid light flash. I disconnected teh LH, noid light flashed again. So, we now knew the harness was good.

Some where along the way, DaveK9 found a writeup on how a bad tach can disrupt/corrupt the signal to the LH. This signal goes through pin W11. We didn't have a pin extractor, and tried ever combination of tools to try and get that pin extracted. Finally, after about two hours of fudging around, we just cut the wire.

VROOM!

Had this been an auto, we would have also inspected the kickdown relay, as I believe this same signal travel through or is in the same circuit as the kickdown relay.

So for now, at least the car runs (first time in three years). The tach doesn't work, but it runs and runs strong.

We will have to figure out what the exact cause is, but that can wait.

Next on the agenda is to SharkTune the Pizza-mobile.

EMan 928

A huge thanks to Andrew and DaveK9 for getting this car running again!

Does anyone know if this automatically means that I need a new instrument cluster? Or, is there still a possibility the tach can be repaired, or is there a way to fix the circuit that Andrew needed to cut to get the car to run?

worf928

Eric, that's a question for Alan. In the meantime, AO? Post the link to the write-up Davek9 found.

EMan 928

Thanks, Dave.

Which Alan are you referring to?

Mrmerlin

I would still suggest to follow the instructions in post 5, we had a car with the same issue where the tach wire shorted out the injectors, if the car was running then parked then it wont run chances are very good that sitting had created a situation where moisture has gotten into the CE panel and the resultant corrosion takes place,
NOTE the corrosion may also be in the pod connections.
The deoxit should restore the connections you will usually see where the pod lights are brighter and other systems seem to work better.

worf928

https://rennlist.com/forums/members/6055-alan.html