3-Series (E21, E30)Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.
my 1986 bmw 325es won't start. Replaced the fuel pump, new alternator, battery is a year old and is on a battery charger every few days. The car is turning but it just won't start. I took it to a tuffy's mechanic (i know, not the smartest move but i was desperate) they said it was the ECU. they said the engine is getting no spark, the crank sensor is registering. they checked (and i confirmed) the timing belt is fine. I spoke to another bmw mechanic and he said that the ECU very very rarely goes out on those things. Help, i don't know what else to do . Any suggestions would be great!
i think i've narrowed it down to either a fuse or the ECU. I haven't had much time to spend with it because i've had work non-stop since this weekend. If it is the ECU, do you know if i need to get it flashed for that specific car with the vin # or is it just a plug and play type of thing. Any information you guys can give me would be helpful.
there are only 3 things that will stop an internal combustution engine from firing at all, spark, fuel and air. gotta be one of these 3 things....air is typically not one of these 3 things so it's gotta be spark or fuel..... a fuse or the ECU is too widely varied in scope....I think it's something simpler....not a computer problem...work this as a mechanic would without any prior BMW experience, just as if it was another brand......
in 25 years of working on german cars have I never heard of, nor seen, the computer go bad, never ever ever.....this includes VW, Audi, BMW and MB, never have I ever seen the ECU go bad...ever...gotta be something else.....
Then what can it be if there is no spark? I've never seen an ECU go out on any of my BMW's either, but I'm at a loss. I'm gonna spend all weekend checking all the fuses and electrical connections. The coil is good, that was one of the first things i checked. What else can it be if its not a fuse? the fuel pump again?
no spark, I would suggest removing the coil completely from the car and inspect the high tension terminal, they tend to break. before that I would also recommend making sure you have low tension voltage hitting the coil. Also there should be an extra line from the spark plug harness that comes off the one of the plug wires (1 or 6 I think, I can't remember) that goes over to the intake side of the motor to a connector there abouts. I would check that out as well. It pulses the TDC sensor to get everything rolling ...good luck
Last year I picked up an 86 eta for $300.00 that hadn't run in a couple of years. Same deal no spark, and no fuel, the crank sensors were working fine, it had been through a bunch of people, and a few new parts here and there, but still nothing. All that time it was the #2 relay, or Main Relay, which powers the DME and also sends power over to the fuel pump relay if I remember correctly. I just picked up that relay from a parts car, I had gone to Advance Auto but they didn't have the right one, BMP Design has them for $23.95 part #114391, I looked on their website but it's a little confusing, I'd call them, their catalog was more helpful in picking out the right relay. Hope this helps.
Here's the update. last night when i was working on my car, i noticed that the fuel pump does not always go on when i turn the key to "on" before i start cranking the car. I also REchecked the coil and REchecked the crank sensor. i checked all the fuses and relays that are under the hood. I tested as many connections as i could get to. I'm at a loss, i'm basically down to the fuel pump which does pump fuel EVERY TIME i crank even tho it doesn't come on right away or it has to be the ECU.
Are there anymore fuses or relays that i need to check anywhere on the car. I heard there was a relay that provides power to the ECU itself, if anyone knows where it is, please share.
Thank you guys again, in advanced, for all your help.
The fuel pump won't always kick on, it will the first time to prime the fuel system, and then after that the car has to set for a little while, maybe a couple of minutes before it will try to prime it again. The relay that you're talking about is the #2 or main relay. Next to the driver's side front strut tower there are three relays, two of the relays should be at the same height, and one, the front one I believe, is lower. They may be hiden under a little black box plastic box, maybe 4 inches long and 1 1/2 inches accross. The lower one is your #2 relay. Try removing the relay and look at the prongs on it to see which prongs is what, and take two jumper wires, just two pieces of wire maybe 3 or 4 inches long, plug them both into the "30" socket, and run one to the "87" and one to the "87a" socket, and see if the car starts. I don't remember right off which is which, but either 87 or 87a sends power to the ecu and the other sends power to the fuel pump relay which is right next to the #2 relay. If it starts then you've found your problem. That's what fixed mine, and yours sounds exactly like what was wrong with mine.
OK, if that's what you think then I would do this. Locate the fuel line to the rail (inlet) and, after relieving pressure, put a rag around the end and have someone crank the engine. If the fuel pump is OK fuel should saturate the rag immediatley. If the rag remains dry then, yeah, somethings up with the fuel pump/delivery system. Good Luck
I mean, seriously, what do you think mechanics do in the shop when you drop the car off and go off to work and worry? that's where they start, every time. If no fuel pours then it can only be the pump or an extremely clogged filter right? These cars are not co-dependant like that, that the ignition will trigger a fuel delivery issue...and vice-versa...they don't work (or not work) like that....
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