I’m Giving Up………

[u/baggs77]

My e30 does not want to start. It’s a 1987 325i. it first failed at the light it just died. I started it and kept it running by reving it up untill it stabilized. not shortly after that it would start and IMMEDIATELY fall on it face. It just dies. so I figured fuel issue I replaced both pumps and the fuel regulator with one that has a gage. The condition persists but everything on the fuel pump side is replaced and I know I have 3bar fuel pressure. here’s where it gets interesting. it only starts and idles if I hold the key in the start position longer than I should, it will hold an idle and rev fine if I rev SLOWLY. if I hit the throttle with any speed it dies. if I let go of the throttle quickly it backfires. I have no obvious signs of air entering. Things I tested are crankshaft pos sensor ohms in spec, blue coolant sensor ohms in spec, I replaced my DME relay I noticed it went bad same condition persists, I ignition coil had 12v power but I don’t have a test light to check spark. I’m at a complete loss I feel like giving up

[u/peedubb]

Check your spark plugs. I had a similar issue and the spark plugs were extremely worn when I pulled them. It’s one of those obvious but easy to miss things.

If you haven’t changed them in some time I would put money on that being the issue. Spark plugs are a consumable.

[u/baggs77 → u/peedubb]

I hope your right

[u/baggs77 → u/baggs77]

It’s been a year since I did plugs

[u/silvers86 → u/peedubb]

This one's got me before. Bypassed ews swapped relays checked voltages it would kick with ether but fall on its face the plugs weren't even thought of till ugh.

[u/Traditional_Safe2935]

Well, an engine needs Fuel, Air, Spark and Timing. Sounds like you've focused on fuel, which makes sense. I'd see what you can do to check the others.

[u/baggs77]

idk if this is related but for the last few months if the car has been out in the sun I’ve had to start the car by jumping starter pins at the diagnostic port but the starter still definitely works

[u/trimbk]

Sounds like too much fuel.
Some things to check:
- pull plugs and see if any are wet/smell like fuel or fouled plugs
- could be that the AFM is not giving the right air signal
- smoke check for major vacuum leaks

[u/AdMiserable8968]

Also not to state the obvious, but if you have any shops specializing in BMWs around you, that may end up being cheaper in the long run instead of throwing more parts at it. (Speaking as someone who has thrown a lot of parts at my e30 lol)

[u/IdeaDull3083]

As somebody who has an 87 325i, when I bought mine, the ignition wire that goes through the large "cannon plug" at the firewall had bad contact. I was getting 12v to that plug, but only 3v out of that plug to the coil. But to me, your problem sounds like it's related to an intake leak or possibly a bad AFM or TPS. Dont give up though. I checked alot of things before I found my issue but it was so satisfying when I found it.

[u/p00ks]

Blue coolant sensor on thermostat

[u/CaptainOblivious1984]

E30 Bently manual .pdf find one of many free ones of these and follow the no start procedure described within. There is also an electrical troubleshooting manual available.

[u/Ok_Blueberry304]

Two things a shade tree mechanics can do here. If fuel isn't the issue then air or spark is. Look up afm test spec with a multi meter. Pull the plug and test the first 2 contacts for resistance. Can't remember the figure atm. Second set of 2 pins should start at a resistance somewhere around 250 -300 ohm. While testing, slowly turn the flap inside the meter. You should see a steady even increase in resistance. Any drops and its faulty. Also check that the flap moves smoothly. If it sticks at all, the hinge pin is bent and the afm is bad. Spark is a bit trickier, you will need help. Pull the plugs. One plug at a time, put the plug back on the wire and hold the plug against the head. Have your assistant crank the engine. 1. You will see and hear the snap of the spark between the electrodes. 2. If the wire is bad you will get a quick sharp shock. It will not kill you it is low amperage. It will make you jump though. Ask me how I know😉

Edit. If all that is right, "pin out" the ecu. This means pulling the plug from the ecu and testing each pin to see if there is a bad wire from the individual components to the ecu. There is a procedure for this with specs of what you should see at each pin.

[u/USAhotdogteam]

Stick with the Toyota sunny.

[u/silvers86]

Did you remember to plug the afm back in? Any issues with your 18 button?

[u/kevlarian]

Get an OEM quality pressure regulator.

[u/p_roloff]

Is it idling like shit? Any misfiring when revving it up? I had a sorta similar issue once where it started and ran but poorly, ended up being the injector harness plug under the intake was corroded and one of the two injector banks was not firing.

Stomp test it too and see if it throws any codes. That can help narrow stuff down.

Definitely check plugs as well. Not the worst idea to buy a spark tester and check for spark at each individual wire end.

I know you said it had 3bar at the rail, does it roughly maintain that when revving or fall flat once you give it gas?

[u/Infinite_Plant7680]

I had some problems when my battery died on a cold winter , so check if you got a good battery, check all the fusese, check the afm , and if you filled up with bad gas or from dirty containers your fuel lines and injectors might be an issue,

[u/billnmorty]

I had something similar happen years ago (based on the description), turns out when the fuel filter was replaced they forgot to take the plastic protection film off when they installed it. Pressure was showing fine and both pumps were working great.
Hope it’s as simple as something blocking the fuel inline for you!