No start issue help - Car was running fine - Wall of text

[AllydNYC]

Having a no start problem with my E30 that is way above my knowledge and it randomly comes and goes.

Looking for advise on where to go with my M52 OBD2 E30 random no start issue... when it happens again.I think this is beyond what I can troubleshoot. I've tried all I know and what I can Google with it being a swapped car. I'm unsure of where to look next.

Short story:

The car was running like a champ for months and then air condition was added (A/C was added by a decently-known indie shop) and the fuel pump was replaced for a new VDO one as preventative maintenance. The swap harness was professionally done by Kadunza. The car originally would crank but with no fuel pressure. I was told the fuel pump connector were old and didn't stay on the pump well, so they were zip tied onto the fuel pump to stay put.

That fix didn't last long. The car started having a new no start issue, it now won't even crank. This issue happens randomly. I can drive the car to the Pavilions and then do a long cruise and it start over and over with no issues. Other times, I can leave it in the garage for a week or two and then it won't crank/start. Let it sit for another few weeks and then it starts right up.




Long story:

The initial issue happened 30 miles after the A/C and fuel pump were done. Car would crank strong but no start. Removed fuel line, zero fuel pressure. Nothing came out while cranking it over. Only other thing I was able to find was that the fused line from the battery to engine bay reads 1.8v, a short somewhere, I assume. Unplugging the ECU would bring the voltage reading back up to 12.x volts. Plugging it back in resulted in the same problem. I unplugged everything A/C related and even the fuel pump. It didn't do shit. Same 1.8v reading. I even went as far as putting my old pump back in, still the same thing. Cranking, 1.8v reading from the fused line, no fuel, no start, Battery is good, terminals are all checked out. I also make sure engine and main harness power is grounded out. That all seems to pass. I checked the main and fuel relays, they click on with power and I also checked resistance, everything is fine.

Car randomly started after sitting for the night so I brought it back to the indie shop that did my A/C. He said it was unrelated to anything A/C and the connector to the fuel pump was loose/worn from age. A few zip ties later to hold it onto the fuel pump securely and it seemed to be fine. I do not understand this since even unplugging the fuel pump days prior did nothing to change the voltage reading. Nor did wiggling the 'bad' fuel pump connector or fiddling with it after temporarily putting my old pump back in.

----

Took the car to Bimmerfest and starting having new issues. The car randomly died on me once when sitting idle in Downtown LA. Turned the key to start it again and it did nothing. I waited a minute and turned it again, nothing. Waited another minute, it cranked over. I then recalled having an issue that morning, I thought my mind was just fatigued at the time. I went to turn the car over and nothing happened. I went to 'Off' position on the ignition and then turned it over again, started up.

I still have these issues randomly. The car does not crank. Turn the key to turn the engine over and nothing happens. I'm unsure of fuel pressure/if the fuel pump primes, I've been to frustrated and it's been way too hot to troubleshoot. Fused line now reads something around like 2.x volts when this no start issue presents itself, if I recall correctly.

Some days I'll go in the garage in the morning and it won't crank. Other days it will start multiple times throughout the day. More recently, I went to a car show and then did a cruise around a lake, ~100 miles and it worked fine after multiple starts.

I immensely miss driving it and really dislike the uncertainty when it does work, unsure of how temporary that is.

Oh, the ECU; TRM Tuning MS41 Swap Tune

[pazi88]

That's pretty obivous. You have faulty wire/connector somewhere. You just need to hunt it down using multimeter. Easy as that.

[Reckless_Havoc]

I just had this happen with my S50 swap. It was a loose wire at the battery junction under the hood. (325i, battery in the trunk)

[AllydNYC]

I rewrote and updated my post above. Any advice? I wonder if it's the ignition switch. The ignition tumbler is so worn that it doesn't even lock the key in there. The chassis has 250,000 miles on it. It leads me to believe that the switch could be worn out as well. I can pull the key out when the car is running and put it in my pocket if I desired to.

[raj]

You almost certainly have a bad ground. I would double and triple check the main engine ground.

[Sea Aych]

You almost certainly have a bad ground. I would double and triple check the main engine ground.

I doubt fuel pressure/operation would prevent the car from cranking.

Engine ground is the easiest thing to check/replace quickly and cheaply. Those wires get corroded pretty frequently and often don't look it from outside the insulation.

Not exactly the smartest move, but when this happened to me, i confirmed it was the ground by, when i was in a no crank situation, just using a jumper cable from the engine mount arm to the shock tower and trying to turn the key. It immediately cranked, so I replaced the engine ground and continued on (did not let it fire up, just wanted to see if it would crank).

Hopefully it's just that!

[exhaust]

+1 on a bad ground or power connection.

I had a similar issue on my Tacoma and it ended up being a corroded positive terminal.

Start with the simple stuff; check your terminals, check your main grounds, and power connections. Make sure that the connections are clean. Neither the AC nor the fuel would contribute to a no-crank situation.

It's incredibly frustrating when an intermittent issue like this comes up, it just needs a cool perspective. Keep us posted