D90 won’t start, need help

[JohnnyBootlegger]

I hate to post here because I’m mostly a lurker, but here goes. I’m working on a 94 NAS defender d90 for a friend. It was in his garage, driven a few days earlier. We originally thought it was the fuel pump because it cranked with a shot of

 

[JohnnyBootlegger]

Ether. It has a new fuel pump, good fuel pressure, good spark, timing is good. The problem is the injectors aren’t opening. I put a noid light on the injector plug and it doesn’t light up. I believe the ecm Is supposed to ground the injector to make it fire. I tried the ecm out of my 95 RRC and it still won’t crank. Switched relays around also. Any ideas?

 

[NatersXJ6]

Oil pressure? Does it have a low oil pressure interrupt switch?

 

[JohnnyBootlegger]

Not sure, will explore that option thanks. The oil level is fine. The engine turns over fine.

 

[mpinco]

Year? Ignition type? 14CUX ECU?

Do you have spark? The ECU won't fire the injectors unless it sees pulses from the coil.

 

[JohnnyBootlegger]

It’s a 94 NAS 3.9, the spark is fine. Like I said, It starts right up with ether. I did just check and there is power going to both pins on the injector plugs. I assumed only one side should have power?

 

[mpinco]

Injectors are solenoids actuated by applying ground to 2 banks. When not operating you should see the power side of the injector bank on the ECU side of the injector, basically both sides of the injector banks show the same voltage when the ECU is not firing the injector bank. I asked about spark because the ECU requires a signal from the coil, -ve terminal, through a drop resister to 'see' that it has spark before actuating the injectors. See in-line resister, item 15, on the schematic attached. Is the ECU getting that signal all the way to the ECU, pin 39? Need to pull ECU connector and ohm it out.

A good overview of Lucas EFI. Includes pin-out of 14CU/X

Service and Troubleshoot Rover 14CUX Electronic Fuel Injection

Specifically read down to the section that speaks to "not a tune resister".

 

[JohnnyBootlegger]

Thanks for that great info mpinco. Looking through it now.

 

[rlynch356]

you should go over to defender source for most of these questions..

But you need to check the spark from the coil to the cap and from the cap to a plug, not just once.. the rotor button fail as well as the caps..
Check that the fuel and ECU relays are working (you need both, if you switch a bad one around you just move the problem and it still wont start)

95% chance this is ignition related.

 

[JohnnyBootlegger]

For the third time, there is SUFFICIENT spark. Does anyone even read what’s already written? The engine will run with ether, that means there is spark, correct?

The injectors are not firing. Mpinco, the link you sent was great. I do have 7.2 ohms at the #39 pin which is slightly higher than the 6.8 suggested. I pulled the resistor and used a jumper to see if there was a difference but it still doesn’t start.

I changed the fuel pump and fuel injection relays with the recommended Bosch part numbers.

I have continuity to all injectors on the left and right bank, each with the correct ohms.

Still nothing. Thanks for all the info so far. I’ve read 5k posts on google.

 

[mpinco]

In summary:

- Good fuel pressure at rail? 30+PSI?
- Spark at plugs
- Injectors firing? A simple DVM won't see the 3ms to 9ms pulse
- MAF in good shape? (unplug to test)
- MAF air leaks?
- Any diagnostic trouble codes?
- Engine coolant temp sensor at correct value for measured temp?


Note that the ECU reads the coolant temp sensor and also fires BOTH banks of injectors for cold start fuel load. No signal from coil? No injector fire. Wrong temp sensor value? Won't enrich fuel load to allow it to fire cold. A lean cold start (not enough fuel) likely will result in a backfire.

 

[evilfij]

Bad/disconnected “chicklet” which is the resistor in the loom.

search chicklet on defendersource

also assume your tried to start it foot to the floor.

 

[rlynch356]

For the third time, there is SUFFICIENT spark. Does anyone even read what’s already written? The engine will run with ether, that means there is spark, correct?

No signal from coil? No injector fire.

good luck

 

[NatersXJ6]

Curious... did you figure it out?

 

[JohnnyBootlegger]

After a ton of trial and error, and reading tons of posts on google, I got the truck to run today. The culprits were the ************** fuel injection and fuel pump relays. I had previously switched the relays around, still no injector pulse. New relays from NAPA with crossed over part numbers and one of the relays would buzz when the ignition was switched OFF. Bit the bullet and ordered relays from Rovers North that came in today, and it fired right up. So apparently something is different in the relay. I will try to post more info after I compare the napa with the RN relay. Thanks for everyones help.