Help me solve my fuel problem! NV m50

[1mz]

The Car: 1991 318i
engine: 1992 NV m50 from an e36

Symptoms: If/when the car starts, the idle shoots straight up then dies out, if the car is shut off, it won't start again.
What I have checked/replaced:
Crank/cam sensors - good
Spark plugs/coil packs - all good
Coolant temp sensor plugged into the harness correctly - good

I tried to check my fuel pressure last night, unsuccessfully. The gauge I bought from autozone was made for a schrader valve, which to my knowledge (now), this car does not have. I'm working on getting the right sized t-fitting and some extra fuel line to check the pressure, unless you fine gentlemen have a more efficient/easier solution for this.

So, I believe this narrows it down to a few things -
I THINK that it could be one of the following -
- bad fuel pump - need to be able to check pressure first though..
- bad fuel pressure regulator - although, the plugs were NOT that wet with fuel after cranking
- bad/clogged injectors? - I was told they were good and tested though, bought them from a r3v member
- bad MAF - I fried a ground going to the maf a while back that might have killed the maf itself, however, my issue still persists with the maf unplugged

I dunno r3v, what does this issue sound like to you. Or have any of you experienced things similar to this in the past?
-

[jeswaw]

It may not be a fuel related problem. What does the car try to do when you start it after the problem occurs?

[1mz]

it just cranks, nothing else.

[psyber_0ptix]

you can test to see if the injectors are firing, test light.

what did you do for a charcoal canister, did you delete it? just curious.

You should be able to hear your fuel pump when you turn the car on; if not, then just rip the back seat out and have someone sit back there waiting for a hummmmm.

you can unhook the return line and see if it will send fuel back (into a gas container of course) by just letting it prime quick.

if all else check grounds and maybe pick up some rebuilt/tested injectors.

[jrdeamicis]

Well fuel pressure and spark come with the crank sensor. Did you verify you had the crank in the right connector and its the one for your car?

Who did your adapter?

Verify you have 12V @ the ECU. The switched and unswitched variety.

Also make sure you have +12V on your fuel pump wire in your adapter harness.

You can meter your Crank sensor from the x6000 connector. It should show mV while cranking. That is of course its a VR sensor on the front wheel. I so rarely touch the NV motors.

Its way easier to do everything from the x6000 while back probing the connector.

www.wedophones.com has the ETM for your car if you don't have it. And the one for your motor.

Start with verifying 12V at the ECU
Then check your crank signal
Then check for 12V while cranking @ the adapter.

[1mz]

you can test to see if the injectors are firing, test light.

what did you do for a charcoal canister, did you delete it? just curious.

You should be able to hear your fuel pump when you turn the car on; if not, then just rip the back seat out and have someone sit back there waiting for a hummmmm.

you can unhook the return line and see if it will send fuel back (into a gas container of course) by just letting it prime quick.

if all else check grounds and maybe pick up some rebuilt/tested injectors.

- I'll check the injectors, I deleted the charcoal canister, and I will take out the back seat, again, and take a listen
-I've got the block grounded on both sides to the chassis and the other grounds all appear to be correct

[1mz]

Well fuel pressure and spark come with the crank sensor. Did you verify you had the crank in the right connector and its the one for your car?

Who did your adapter?

Verify you have 12V @ the ECU. The switched and unswitched variety.

Also make sure you have +12V on your fuel pump wire in your adapter harness.

You can meter your Crank sensor from the x6000 connector. It should show mV while cranking. That is of course its a VR sensor on the front wheel. I so rarely touch the NV motors.

Its way easier to do everything from the x6000 while back probing the connector.

www.wedophones.com has the ETM for your car if you don't have it. And the one for your motor.

Start with verifying 12V at the ECU
Then check your crank signal
Then check for 12V while cranking @ the adapter.

-tried switching the plugs for the cam and crank sensor to see if I had them wrong, nothing happened so I put them back the way I had them originally when it at least started.
-The adapter was made by a member on here for me - forget his name but he makes them for everyone - reputable guy and pretty solid quality, and I did check the pin out when I had the original grounding issue over a year ago.

- I'll check the things you listed at the bottom here tonight/Saturday


thanks for all the suggestions guys! If you can think of anything else, let me know

[Wanganstyle]

mine did not fire bc I mistakenly connected the crank position sensor to the oil pan sensor item. same 3 wire plug, after correcting it fired up happy.

[1mz]

I'll give that a try as well waganstyle - once this car runs, I am going to test that DME of yours, I'll let you know the results.

[psyber_0ptix]

- I'll check the injectors, I deleted the charcoal canister, and I will take out the back seat, again, and take a listen
-I've got the block grounded on both sides to the chassis and the other grounds all appear to be correct

how did you delete it and what did you do.

I had,not knowing any better, blocked the line leading from the canister to the tank...which created a vacuum lock fighting the fuel pump. It would crank, an start up but then just lose steam and die. The injectors would fire, but no fuel would be drawn from the tank with every attempt after. Once I unblocked/uncapped the line, it started up no problems.

just remove your gas cap and see if it helps

Cliffnotes:

Make sure the vacuum line to the Throttle Body is capped, but the line leading from where the canister was to the tank, leave it open to air

sorry bud, thats the last idea i have

[Wanganstyle]

I'll give that a try as well waganstyle - once this car runs, I am going to test that DME of yours, I'll let you know the results.

Yes, mos def. Im 100% that dme is working, video of the m50 running before tear down for s52 is somewhere on my CPU.

[1mz]

how did you delete it and what did you do.

I had,not knowing any better, blocked the line leading from the canister to the tank...which created a vacuum lock fighting the fuel pump. It would crank, an start up but then just lose steam and die. The injectors would fire, but no fuel would be drawn from the tank with every attempt after. Once I unblocked/uncapped the line, it started up no problems.

just remove your gas cap and see if it helps

Cliffnotes:

Make sure the vacuum line to the Throttle Body is capped, but the line leading from where the canister was to the tank, leave it open to air

sorry bud, thats the last idea i have

ya know.... that sounds spookily familiar. stay posted for results tonight

[jeswaw]

Hopefully what psyber shared will help you with your problem. Keep us posted!

[Wanganstyle]

also, try to fire it on starter fluid; brake fluid cleaner or carb cleaner will also do in a pinch. one easy way is to spray it on the air filter, it will evaporate and get sucked into the engine, if the ignition system is firing, car will idle on starter fluid - thats what its designed for ....starting!! and idling if electronics is functional.

2jz/s52/s54 will idle on starter fluid only, its pretty fun.
beware of intake backfire! be careful!!

[1mz]

well found one issue - definitely vacuum capped the charcoal canister return line - the pump was fighting the suction this whole time... didn't release the pressure first though, undid the vacuum cap, fuel everywhere, before I could open the tank and release it, a solid amount of - OLD gas all over the driveway haha