1985 318i will not start

[skillet318]

My son has an 85 318i and it will not start. It was running fine, died, and has never started since. Things I have done:
Changed fuel filter
Checked for spark at coil and plug 1 both work.
Changed out AFM
Getting fuel to rail with good pressure and pump is working fine.

Need help, engine cranks fine, but it will not start. Sometimes backfires during this process.

[NoM54me]

Check the reference and ignition speed sensors. Perhaps the OBC relay has crapped out, that's what happened to me.

[skillet318]

Can you tell me where to find (on the vehicle) where those 2 sensors are?

[NoM54me]

They're on the transmission bellhousing, usually nearer the bottom on the driver's side. They're identical and side-by-side, so take care to notice which one goes where. The ECU needs a signal from each to know when to fire injectors. If one or both is bad, you get a no-start. You test them for resistance at their connectors, search for procedures.

[hahaitzskippy]

Check the reference and ignition speed sensors. Perhaps the OBC relay has crapped out, that's what happened to me.

They're on the transmission bellhousing, usually nearer the bottom on the driver's side. They're identical and side-by-side, so take care to notice which one goes where. The ECU needs a signal from each to know when to fire injectors. If one or both is bad, you get a no-start. You test them for resistance at their connectors, search for procedures.

what and where is the OBC relay?

i was under the impression that the m10 does NOT have a speed sensor and it uses the distributor to know when to fire. i have been under my car a lot and i only see 1 sensor. and that sensor is in the tranny.

can someone show me a photo?

[milolang]

Getting fuel to rail with good pressure and pump is working fine.

I had issues with pressure but it ran fine for year then I could not start the car, it turned over just never caught, I came to a conclusion with troubleshooting and it was kind of a guess which proved to work, I changed out my Fuel Pressure Regulator (FPR) and that baby fired right up.

[cgk_iii]

sounds like your timing is off. if you take distributor cap off, rotor should be pointing to spark plug wire #1 on the cap.

take out spark plug #1 to cylinder head stick your finger in side and have someone crank it over very slowly 1 crank at a time until you feel the compression stroke at cylinder 1.

have someone look down the hole on your bell housing, right next to the starter to see the flywheel while someone else turns the motor by hand.

there should be a little T or some sort of notch you can see on the flywheel.

once you see that marking you should be at TDC..

once at TDC take out distributor, reinstall and notice that the rotor will turn about 180 degrees when you put it back in so compensate and make sure that you end up with the rotor pointing to #1 on the cap.

fire up the car, take out vacuum line to distributor and use a timing light to see if you are at the right degree of timing. if the degree of timing is off, loosen the distributor and SLOWLY turn until the correct degree is met.

you probably won't really need a timing light, but its the 'right' way to do it. first time i did it with a light and the 2nd time I just did it by ear.

hope that helps! :)

PM me if you're unclear on some of the steps i provided, and ill try to walk you through it.

[cgk_iii]

They're on the transmission bellhousing, usually nearer the bottom on the driver's side. They're identical and side-by-side, so take care to notice which one goes where. The ECU needs a signal from each to know when to fire injectors. If one or both is bad, you get a no-start. You test them for resistance at their connectors, search for procedures.

these sensors you speak of are for 'e' cars

[gettinscurvy]

I'm having a similar issue. Subscribing for solution.

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