Firstfives.org

Hey All,

Just over 5 years since my last post. Over the last decade my available time with the car dwindled to a drive once or twice a year. I dealt with some personal issues in 2022 which kept the car covered and finally got around to it in late '23 with no luck. I got motivated late last year and had to start with a fresh battery. With power, I was cranking but clear that my fuel was extremely bad - think the worst you have seen. Not sure when I last put any in but it was probably numerous years.

Two weeks ago I siphoned the tank almost completely dry and confirmed how bad the fuel was. I refreshed about 2.5 gallons of premium and the car would stumble and try to crank but never get there. I replaced the regulator with slight improvement then today replace the fuel filter (also nasty) and even better but no luck. I was fortunate enough to find a new in-tank pump and main pump (aftermarket) at a local parts store which I also replaced today. At this point it looks like we are getting good, clean pressure to the rail but still no start. What is odd is I get about 2 strong attempt then it will crank with no hope until I let it sit and try again.

I swapped the ECU and AFM separately with no improvement. When it does hit, it seems strong for just under a second then dies out, just won't fire up and stay going. I am so far out of the game that I do not know what to check next - all my hoses look good, connections are clean, fuses are good. A lot of stuff under the hood was replaced in the time I have owned it with little drive-time and climate-controlled storage for over 17 years with me.

I think there is an obvious chance the injectors are plagued by the bad gas but I am curious why the pattern of 2 close starts then nothing keeps recurring, almost like the car thinks it is good then pressure drops and it dies.

FYI - I have close to 5 gallons of fuel now. A bit of seafoam and got a little injector cleaner direct into the rail as well. Car is an '81 model with the stock engine but has the E28 cooling system and a handful of other unrelated mods to this issue.

Any advice is much appreciated. My goal is to get it running then I can get back to the resto and tackle a few other issues, just need the motivation to hear that engine fire up.

Thanks!

I had a similar problem with mine. It had sat at a shop for years before it was gifted to me. I tried all the things you did. After many failed attempts I tried an old school trick of using starter fluid to start the car and keep it running with it. Did this multiple times for periods of maybe 5mins. Once I got it to where it would run like crap on its own. I then I ran about 2 bottles of Chevron Techron through it before I could get it to start and run smooth on its own. Good luck!!!!

Josh! Long time no see.

I would first verify fuel delivery, detaching the return hose from the FPR and running the fuel pump by pushing on the AFM flap. See what the fuel looks like coming out of it, and continue to run it to flush it if you think it's needed. That's after the FPR so you would then know it has enough pressure.

Especially as it's been sitting, a caution. On a couple of different BMWs, including my last E12, the fuel lines were bad going to the main pump. They didn't leak externally, but would allow the system to suck air, and not build fuel pressure. Since you have a new and presumably working in tank pump, this is unlikely, but something to keep in mind.

Verify spark of course, which I suspect you already have. Given that you said it was in climate controlled storage, the following is unlikely, but still possible. Since the spark plug wires have a solid conductor, you should get spark thru them, however the insulation can break down which is very hard to determine, but it can crossfire so to speak if it's bad, or even to ground. If it had been stored outdoors that would be much more likely.

Then along the lines of what Vintage suggested, prime it. Either by dumping some gas into the intake boot or by either starting fluid or just plain old spray carb cleaner.

If you get it to sort of run that way you can check the injectors. You would have to remove them, or the fuel rail assy, which is kind of a pain, but doable, then take the dist cap off and rotate the rotor back and forth. I've found there is enough play in the centrifugal advance to generate a pulse which would then every 3 times generate a pulse to the injectors to fire. They're batch fired of course so they all fire at once, once per engine revolution which is 3 compression cycles. So you'd need something to catch the fuel as it hopefully sprays out of the injectors.

Mike (or anyone else), if the fuel pump energizes when pushing the AFM flap, does that rule out a bad double-relay? I think so.

Ditto what Mike says, I just replaced the fuel lines on my car, and the ones between the in-tank lift pump and the main pump were dry rotting and in bad shape. You might have cracked the feed hose while moving it around to replace the lift pump. Of course if the lift pump is working, you'd probably smell gas. Did you bench test your lift pump? I was surprised to find the one in my car was inoperative.

Josh, if you're losing spark, maybe put a meter on the pulse generator in the dizzy and confirm there's a resistance that's not zero or infinite.

Let us know how your progress. And welcome back.

Hey Guys,

Thanks for all the advice. Ultimately this ended where I was started but knew I needed to work my way to - the injectors. After replacing the pumps, filter and confirming ECU, etc was good we eventually ended up at the fuel rail. We were getting good pressure to the rail but were not sure on the injectors. We avoided them at all cost just not wanting to break down the intake but eventually dead. Our rough bench test showed possible dead injectors so I sent all 6 off to a local shop that rebuilt my Buell (Harley) injectors a few years back. All 6 were tested bad, after rebuild 2 were completely dead so I had to buy reman units from them and ended up with a combined fresh set. Finally got it back together yesterday and after priming and 10-15 seconds of cranking she fired right up to a pretty smooth idle.

We were on/off a few times warming up and checking for leaks, etc and when we felt good I did a quick brake check and we did a little trip (5ish miles) to run it through the gears. On the way back in we noticed some front end suspension issues that we will dig into but seems like the fuel system is fresh now. After it cooled down we checked and found the rubber line from the hard line to rail was spraying so we depressurized and cut about an inch off. Same thing - that line is dated back 20 years and seems to be crumbling so I will be swapping it out. I already have the OE BMW part (same part # I have as a spare for the trunk line) so will probably swap that next weekend then we should be good but just knowing we can run well now is a plus.

Next on the list is a fresh oil change, checking out the rear end leak and digging into that suspension.

Thanks again for all the help!

Hey thanks for the follow up. I’m glad you were able to figure it out. If you stare at a problem long enough eventually you’ll figure it out.

Wow, six bad injectors. That's got to be some kind of Royal Flush statistically. Glad you got it sorted out. Must have felt real good when you got that idle.

Reading through Josh’s E12 Revival and wonderful support herein, is a reminder that unintended neglect can disable an otherwise highly reliable machine.

One example, (since retiring here in Tennessee) is I have lawn and garden equipment that I didn’t have in my previous life. I learned via hard knocks that if you’re going to store a mower for several month to fill the tank with 100% gasoline (Non-Ethanol). The ethanol version is cheaper, but it breaks down and goes bad in as quickly as 3 months. Where 100% gas breaks down after a couple YEARS. (Times are somewhat dependent on thermal environment etc).

Also, there was a time until recently, that I stashed a bunch of miscellaneous parts in a few BINs that included about 18 known good fuel injectors, fuel pumps, electronics, AFMs, all available to whoever. My philosophy was “If it didn’t cost me anything, it doesn’t cost you anything (except shipping).

Yeah. That was then. This is now.