Won't start after 17# injector swap. HELP!

[95///M3]

1989 325is. Ran well, swapped out stock injectors for 17# M50 injectors yesterday. Also replaced both coolant sensors that the injector harness plugs into.

Cranked, turns over, no start. Sprayed ether, it starts. Swapped back in stock injectors no start. Swapped to a different DME, still no start.

Pulled both fuel lines, fuel is pumping as it should.

Checked and double checked, fuses, injector harness pins are seated and plugged into engine harness.

Stumped, what next?!

Thanks,

Jim H.

[Jahman093]

Are you getting fuel? Spark?

[95///M3]

Are you getting fuel? Spark?

When I spray ether, it will start, indicating spark.

I am getting fuel to the rail, but haven't confirmed if they injectors are actually firing. My hypothesis is that they are NOT pulsing, will confirm with a noid tester tomorrow.

[lcoleman]

Feed/return lines get mixed up?

[jlevie]

Check C191 (underneath the intake).

[95///M3]

Feed/return lines get mixed up?

Only removed them to check for flow after the no start condition started.

So, no.

[95///M3]

Check C191 (underneath the intake).

I have checked for proper seating of C191 to injector harness several times. Is there a test procedure to probe pins?

[Balleristic31]

Are the coolant sensors hooked up correctly? (Not reversed?)

[95///M3]

Are the coolant sensors hooked up correctly? (Not reversed?)

Checked. Also swapped out sensors for known good sensors in the E30 that is parked beside it in the garage....

[Varinn]

I had this EXACT problem earlier this summer on my 325i. The car was running well and had all sorts of new parts so I swapped in a set of 17# injectors (rebuilt) and drove to work, after the work it refused to start and I found a massively leaking FPR o-ring I replaced the seal and the problem remained.

I swapped back in the noisy stock injectors and it still wouldn't start, checked fuel, spark etc and found nothing wrong. Back to the 17#, still no start and one day I put in the original injectors one more time except I swapped out a couple of them with some other stock spares and the car fired up immediately and ran perfect.

In the process of troubleshooting (and a ton of tune-up items I figured I may as well do while I was solving this) I replaced these parts with new oem:
CPS
Coolant temp sensor
FPR
Fuel Pump
Fuel Filter
All fuel lines
Cap
Rotor
Wires
Plugs
Main relay
Fuel pump relay

Before replacing parts I had cleaned the fuel injection connectors and tried a spare DME, CPS, relay, etc. My car already had all new vacuum hoses from when I installed the motor recently, and the compression tested out perfectly on all cylinders.

You're on the right track, grab a noid light (or stethoscope) and figure out if your injectors are firing or not before throwing parts into the car. In the end the only obvious issues I was able to find was that the injectors seemed to fire at odd times sometimes with 2 or 3 shots and random gaps between when they'd work again. I'm not sure why the problem remained after swapping my stock injectors back in the first time after it showed up, but in the end the stock ones seemed to be the fix.

[95///M3]

I had this EXACT problem earlier this summer on my 325i. The car was running well and had all sorts of new parts so I swapped in a set of 17# injectors (rebuilt) and drove to work, after the work it refused to start and I found a massively leaking FPR o-ring I replaced the seal and the problem remained.

I swapped back in the noisy stock injectors and it still wouldn't start, checked fuel, spark etc and found nothing wrong. Back to the 17#, still no start and one day I put in the original injectors one more time except I swapped out a couple of them with some other stock spares and the car fired up immediately and ran perfect.

In the process of troubleshooting (and a ton of tune-up items I figured I may as well do while I was solving this) I replaced these parts with new oem:
CPS
Coolant temp sensor
FPR
Fuel Pump
Fuel Filter
All fuel lines
Cap
Rotor
Wires
Plugs
Main relay
Fuel pump relay

Before replacing parts I had cleaned the fuel injection connectors and tried a spare DME, CPS, relay, etc. My car already had all new vacuum hoses from when I installed the motor recently, and the compression tested out perfectly on all cylinders.

You're on the right track, grab a noid light (or stethoscope) and figure out if your injectors are firing or not before throwing parts into the car. In the end the only obvious issues I was able to find was that the injectors seemed to fire at odd times sometimes with 2 or 3 shots and random gaps between when they'd work again. I'm not sure why the problem remained after swapping my stock injectors back in the first time after it showed up, but in the end the stock ones seemed to be the fix.

Noid light is here today.

Will post an update after I test to see that the injectors are pulsing or not.

Ironically I replaced a set of stock injectors on my other e30 at the same time an that car runs beautifully. Maybe I'll try to swap this into this car....

Jim H

[tim88325is]

I have checked for proper seating of C191 to injector harness several times. Is there a test procedure to probe pins?

Pull back the rubber boots on the connector to check for damage or corrosion on the back of the pins.

The C191 connectors can be a real weak point on the cars at this point...

[Quinthirty]

I'm curious about your solution. I changed mine to M50 injectors today as the chip was also changed to 24hp Ebay chip. The car is not firing well, won't idle, smoking, and is very rough. It was ok when the injectors were stock and chipped.

[amcink]

Subscribed. I'm seriously considering upgrading to M50 injectors but need more insights. I have a 325e

[bernzpeed]

I installed 17# injectors on mine and an ebay chip and it runs like a champ.