Mystery ignition issue

[Laldog]

I've been chasing this problem for a number of years now.

My starter/ignition system has an intermittent issue...sometimes when you turn the key, it starts just like it should, other times, the electric fuel pump engages but not the starter.

My solution has always been to connect the battery to a jump pack where it starts right away.

What I've done so far...

1. Bypassed ignition switch and installed a push button switch wired between starter and battery.
2. Installed new battery ground strap with clean connection points.
3. Checked battery and confirmed it to be in good working order.
4. Replaced ignition switch wiring (last year).

I have recently purchased all the necessary replacement parts, but seeing that my car has the shear bolts securing the steering column, I'm reluctant to start the ignition cylinder replacement project while it is driving season here in Boston.

I thought using the push button start would have eliminated this intermittent issue, but not true. It happened this morning while I was out getting my state inspection sticker... car wouldn't start when I went to exit the garage (of all places...total embarrassment)

Anyway, I'd love to hear any suggestions or solutions to this long-running (or not-running issue) would be welcome.

(My car is 1973 3.0cs 4 speed with Weber carburetors and a 3.5 engine from E28)

Thanks in advance.

 

[JFENG]

When you turn to crank, do you hear a click/clunk from the starter ?

• If yes, then you might have a bad switch inside the solenoid.
• If not, then maybe you have a starter solenoid that's failing.

If no click, you might be able to replace just the solenoid with a rebuilt Bosch unit.

 

[Honolulu]

Have similar problem, car not started/run frequently.

Key to position 2, get only a click: solenoid engaging, thrusting pinion gear into ring gear, but not successfully activating starter.

Repeated attempts get the engine turning over (solenoid successfully powers the starter).

Removed starter and played with it, lubed what was visible. Did not de-solder the solenoid to access the actual electrical contact to energize the starter. Reinstalled. NOTE, removal of starter requires removal of back carb and intake manifold. Nasty job.

 

[bluecoupe30!]

Have similar problem, car not started/run frequently.

Key to position 2, get only a click: solenoid engaging, thrusting pinion gear into ring gear, but not successfully activating starter.

Repeated attempts get the engine turning over (solenoid successfully powers the starter).

Removed starter and played with it, lubed what was visible. Did not de-solder the solenoid to access the actual electrical contact to energize the starter. Reinstalled. NOTE, removal of starter requires removal of back carb and intake manifold. Nasty job.

Removing starter is definitely a "nasty" job. I hate messing with coolant when taking that back carb off, so I spent some time finding small sockets that would fit the solenoid. Removed that, then I could remove starter and pull that up and out. Installation was reverse of removal, as they say. No carb removal, no manifold had to be taken off, no coolant lost.

 

[sfdon]

Snap on thin walled shallow universal socket belongs in every mechanics tool box.

 

[CTD]

Did you also replace the ground from engine block to chassis?

 

[Stevehose]

Replace with the smaller, more powerful modern starter which is accessible with sockets.

 

[Sean Haas]

I’ve had this too. Always when car is warm, it will crank fine once but if it doesn’t catch and I crank it again nothing, not even a click of the solenoid like it isn’t getting power. If I let it sit a bit it will start fine. Usually when this happens the key feels a bit funny when I turn it, like maybe the steering lock isn’t disengaging properly or something. The starter is relatively new and usually works just fine and battery is always fine when I check it.

 

[Laldog]

Replace with the smaller, more powerful modern starter which is accessible with sockets.

Do you have a particular starter in mind?
I was going to go with the Bosch SR-0445-X which was recommended here, but you've experienced something else?

Thanks in advance.

 

[Laldog]

I did a few things over the weekend, more or less to narrow down what might be causing this issue.

First, I replaced both ground strap cables, one at the battery terminal and the other on the passenger side of engine block.

Next I cleaned up the positive battery terminal, putting in a new connection post and re-attaching cables and wires. Additionally, I ran a new fused wire directly from battery terminal to the push button switch that activates the starter.

Since these "upgrades" I'm batting 6 for 6, with no start failures as yet. (famous last words)

 

[Stevehose]

Do you have a particular starter in mind?
I was going to go with the Bosch SR-0445-X which was recommended here, but you've experienced something else?

Thanks in advance.

I think that's the one, yes. I have the one for the 850i v-12 but that takes some grinding of the starter case to fit, and it may not fit under a stock intake system, @sfdon might know.

 

[Simon]

Sounds exactly like the issue/symptoms i had with my 1975 E9 CS. Was especially bad if not driven for 2-3 weeks or if cold weather. Battery checked ok. but car would usually start if added a jump pack or jumped from another car battery. Fuel pump would run. But wouldnt get the 'click' when turning key. dash lights would dim. when it finally started, it was flooded with too much fuel. Once it had started once, it would start OK until left for a while and cold.
Started with the items you list to try and diagnose. In the end, the Auto electrician eventually diagnosed it as faulty relay (old dry internal circuit board). The large complicated relay, Bosch 0280230001. Bought a good second hand one on ebay as they were extremely hard to source new. - haven't had any issues since. Maybe worth checking on yours?

 

[Laldog]

Wow. Another wrinkle.

Can you tell us where that specific relay is located?

And many thanks for your input.

(Right now, I'm 10 for 10, but haven't driven much due to weather concerns up here in Boston)

 

[sfdon]

We use e32 735i starter for our carbed cars.

 

[Simon]

Wow. Another wrinkle.

Can you tell us where that specific relay is located?

And many thanks for your input.

(Right now, I'm 10 for 10, but haven't driven much due to weather concerns up here in Boston)

My car has been messed with a bit. but see attached images. large relay next to battery. Must have been located near here originally although mine is no longer secured. I have RHD car. But dont see why it would be different in LH Drive.