Random No Start

[Vefu]

Hey r3v... I've had my 84 325e for almost a year now and It's had then same problem that entire time. I've taken it to 3 different mechanics and neither of them could figure out the problem so hopefully you guys can help.

Basically, the car randomly wont start and sometimes when I'm driving the car will just start running really rough and spitting black smoke when I accelerate. When it wont start sometimes pumping the gas will help and it will cough to life but other times it doesn't do anything. I've gotten it smoked checked and there weren't any leaks and I have also replaced the spark plugs.

Hopefully one of you guys can help me figure it out. Thanks in advance!

[Quadrajet]

If you don't already have one, check and see if you have the green label 027 ECU. I had an 84 325e and replaced EVERY item I could and it still went super rich when it felt like it, and wouldn't start. I would check to see about that first, then look at other items with your car.

[Vefu]

Is that the ECU I should have for this car? When I first bought the car it was having trouble starting and a mechanic said it was the ECU so we replaced it with a junkyard one.

[jlevie]

This would first make me think of the cold start system or the timing reference sensors.

[Vefu]

If you don't already have one, check and see if you have the green label 027 ECU. I had an 84 325e and replaced EVERY item I could and it still went super rich when it felt like it, and wouldn't start. I would check to see about that first, then look at other items with your car.

I just went out and looked and yes I do have a 027 ECU with a green label.

This would first make me think of the cold start system or the timing reference sensors.

Are these things that can be checked by someone that has minimal mechanical experience?

[Quadrajet]

If you're gonna start tackling some of these jobs yourself, get a Bentley manual. They are worth the money if you're gonna stick with E30s for any length of time.

[ivangene]

reference sensors (if like the other car I own) can cause this

I am brand-de-new here so dont listen to me, I'm just reading to learn and catch what I can
On my other old car there is a DME relay for the fuel pump....is there anything like that on the E30's? - we keep a spare at all times because they will fail and leave you stranded....

[Vefu]

reference sensors (if like the other car I own) can cause this

I am brand-de-new here so dont listen to me, I'm just reading to learn and catch what I can
On my other old car there is a DME relay for the fuel pump....is there anything like that on the E30's? - we keep a spare at all times because they will fail and leave you stranded....

Yeah there is a relay for the fuel pump, but can a bad relay cause intermittent starting? It's pretty cheap to replace so I was thinking about just buying a new one to see if it helps.

[ivangene]

IDK - I was just wondering myself too
relays can become corroded and work intermittently but so can many other parts - including the fuel pump (had one do that to me)

is the intermittent starting hot and cold - or one or the the other - heat sometimes can influence the no start issue and help people know where to start looking

[Vefu]

IDK - I was just wondering myself too
relays can become corroded and work intermittently but so can many other parts - including the fuel pump (had one do that to me)

is the intermittent starting hot and cold - or one or the the other - heat sometimes can influence the no start issue and help people know where to start looking

The intermittent starting is completely random, it can be cold or hot.

[ivangene]

how old is the fuel filter?
are you using top tier gas?
how is the battery condition and connections?

simple things to rule out
It still could be reference sensor - have they been replaced? IDK about cost but the Porsche crowd likes to use BMW sensors because they are cheaper - not sure what "cheaper" is but it cant hurt

[Vefu]

how old is the fuel filter?
are you using top tier gas?
how is the battery condition and connections?

simple things to rule out
It still could be reference sensor - have they been replaced? IDK about cost but the Porsche crowd likes to use BMW sensors because they are cheaper - not sure what "cheaper" is but it cant hurt

I'm not sure how long it's been since the fuel filter was replaced, I always use premium gas, and the I replaced the battery when I first got the car so that's fine too. I think I'll go ahead and replace the fuel filter and the fuel pump relay and see if the problem goes away.

[Vefu]

Hello there
When you say sometimes it won't start, does it turnover at all or is it turning over and no ignition? has this car's engine been modified?

Engine turns over but no ignition, and the car is 100% stock.

[dnguyen1963]

Fuel + air + spark = ignition. Follow this formula to troubleshoot your problem. First, remove the plugs and verify that you do indeed have sparks. Second, tee in a pressure gauge in front of the fuel rail and observe the pressure when you crank. Third, perform a smoke test to verify that you have no vacuum leaks. Fuel:Air ratio must be correct before the car can start. This is the minimal procedure to do before you look at anything else such as CPS, TPS, Cap/Dist, or DME.