M10 fuel trouble

[WhorifyingHunty]

Well I have an 84 318i and in all my research it seems to be common on the 84 and 85 model years, But I haven't found a complete solution.

The car is having quite a few issues or it seems so. The car won't start at 5:00 am but once it heats up outside to 100 degrees, the car fires up with no problem.

-Things I've checked out-
Both fuel pumps are working wonderfully, Brand new in June of last year.
Fuel pump ground on rear seat has been cleaned up.
5:00 am fuel pressure from 0-25 psi.
12:00 pm fuel pressure is 40-50 when driving.
Fuel lines and tank seem to be fine, gas is pretty clean.
Cleaned up my spark plugs (Bosch)
Starter is at the end of its life but still going.
Checked afm
Checked for vacuum leaks


The car had sat for a year up until 2 months ago, But has been running lately. I know that 84 and 85 models ran a different EFI?

I shot some starter fluid in it this morning and had my dad crank it over, It ran on the starter fluid for 15 seconds and died. We tried giving it throttle but nothing happened!

I'm at a loss of words, I just need some info into the right direction.

If wanted in the m10 section that's my bad, just move it over.

[LJ851]

fuel pressure regulator maybe.

[dnguyen1963]

Have you performed a smoke test to eliminate vacuum leaks? It would seem that as temperature increases certain parts expands accordingly; thus, sealing any vacuum leaks that the engine might have. You can make yourself a DIY smoke machine so you can test the engine when it is cold. Just make sure that you plug both the intake and exhaust and keep the pressure at about 2-4 psi when doing smoke test.

[WhorifyingHunty]

fuel pressure regulator maybe.

Oops forgot to add i checked that out too.

Have you performed a smoke test to eliminate vacuum leaks? It would seem that as temperature increases certain parts expands accordingly; thus, sealing any vacuum leaks that the engine might have. You can make yourself a DIY smoke machine so you can test the engine when it is cold. Just make sure that you plug both the intake and exhaust and keep the pressure at about 2-4 psi when doing smoke test.

I didn't do a huge vacuum leak check but i did do one with carb spray.

[Holland]

Unplug your AFM and try giving it a start. Won't idle for shit but it will tell you if you are having AFM woes.

Sincerely,
Someone who thought it was fuel but actually AFM woes.

[WhorifyingHunty]

Unplug your AFM and try giving it a start. Won't idle for shit but it will tell you if you are having AFM woes.

Sincerely,
Someone who thought it was fuel but actually AFM woes.

Funny story i accidentally unplugged it the other day then later tried starting it up (like 20 times), then realized it was unplugged and it fired up. So that tells me it's not that. Unless its malfunctioning.

[WhorifyingHunty]

I'm thinking that it is an open circuit, any ideas on that?

[WhorifyingHunty]

Just an update, This morning the car started cold and i was super shocked. The problem doesn't seem to just be gone and i won't just accept that it is, I need to figure this out. I daily it so for now its running but any insight? Questions?

[Holland]

Funny story i accidentally unplugged it the other day then later tried starting it up (like 20 times), then realized it was unplugged and it fired up. So that tells me it's not that. Unless its malfunctioning.

Sometimes it's hard to start when you do, but when your car decides to die and won't fire back up it can be a blessing.

Basically, what's happening with my car is that it will intermittently just lose power and die. Sounds like a wonky fuel pump right? Two new pumps, filter, relay, and lines later the car still has issues. Will also sputter and die on startup intermittently. Funny thing is when I hold on WOT, it will sputter but not die. found out later upon unplugging the AFM, the car will actually start and run. Basically it makes the computer go to a default map of sorts and won't idle for shit because the AFM is closed, but it will run.

[thebutterson]

I believe your fuel pressure should prime right to 45psi (unless it's not a 3 bar regulator), and that it doesn't need to be running to prime to that pressure. You can jumper the fuel pump relay so it will run constantly to check this.

Something you should also do is clean the engine grounds: On intake manifold, valve cover to battery tray, and oil pan to frame.

Put a test light on the thermo time switch and see that it powers the light from 1-7 seconds.

If that checks good, check to see if the cold start injector is spraying fuel.

[WhorifyingHunty]

Sometimes it's hard to start when you do, but when your car decides to die and won't fire back up it can be a blessing.

Basically, what's happening with my car is that it will intermittently just lose power and die. Sounds like a wonky fuel pump right? Two new pumps, filter, relay, and lines later the car still has issues. Will also sputter and die on startup intermittently. Funny thing is when I hold on WOT, it will sputter but not die. found out later upon unplugging the AFM, the car will actually start and run. Basically it makes the computer go to a default map of sorts and won't idle for shit because the AFM is closed, but it will run.

Okay that makes sense. This had happened the morning of me unplugging the AFM. So when i unplug the AFM it resets the computer to a default setting? Is that cause it doesn't recognize a sensor?

[WhorifyingHunty]

I believe your fuel pressure should prime right to 45psi (unless it's not a 3 bar regulator), and that it doesn't need to be running to prime to that pressure. You can jumper the fuel pump relay so it will run constantly to check this.

Something you should also do is clean the engine grounds: On intake manifold, valve cover to battery tray, and oil pan to frame.

Put a test light on the thermo time switch and see that it powers the light from 1-7 seconds.

If that checks good, check to see if the cold start injector is spraying fuel.

I run 2.5 -3 bar when idling, I installed a jumper switch with a light that tells me if the fuel pump is running.

I will go through all the grounds tomorrow as you suggest.

Now with the cold start injector at what temperature does it engage? or is useful?

[Holland]

M10 fuel trouble

Okay that makes sense. This had happened the morning of me unplugging the AFM. So when i unplug the AFM it resets the computer to a default setting? Is that cause it doesn't recognize a sensor?

From my understanding, is it maps to a safe, middle of the road map because the AFM is no longer adjusting airflow.

Also from my understanding, aside from the magnetic track that wears out, there is a hot wire that can get dirty and mess with the resistance, causing faulty readings and cause the AFM to fail and kill the car. This is the problem I'm dealing with at the moment.

[WhorifyingHunty]

From my understanding, is it maps to a safe, middle of the road map because the AFM is no longer adjusting airflow.

Also from my understanding, aside from the magnetic track that wears out, there is a hot wire that can get dirty and mess with the resistance, causing faulty readings and cause the AFM to fail and kill the car. This is the problem I'm dealing with at the moment.

Hmm well that's good to know. Any luck with your issue?

Just an update 9/8/13

8:40 a.m. I went to start the car to head to church, Didn't fire. (5 cranks)
Weather: Rained and like 70 degrees i think, nice weather.

12:10 p.m. Arrived home from church and tried starting it up, didn't fire. (5 cranks)
Weather: was around 95 degrees and mildly humid.

2:50 p.m. Started on first crank.
Weather: no humidity, dry ground and 95-100 degrees

It drove well the night before, Drove an hour with no issues.
I have such a suspicion of the weather causing the problem, maybe I'm crazy.

Any ideas? and questions are welcomed.

[thebutterson]

Did you clean your grounds and check the cold start system? Did you verify the fuel pumps providing the proper pressure while cranking?

There's a barometric pressure sensor installed next to the afm, as well as an air inlet temp sensor just prior to it. Try unplugging those.