No crank no start- intermittent issue

[Salawada]

I have a No crank no start issue. But if I jump start the car with another car it fires right up. And may even start up a few times afterwards. Never actually cuts out.

But then at some point it goes back to no start. If I wiggle the wiring near diagnostics it may fire up on its own.

I have replaced main, fuel pump and starter relays. Car has new battery and in-line fuel pump and filter.

Once started car runs strong.

Any suggestions? Is there any spray on cleaners that may help? Anyway Incan bypass the wiring issue?

Thanks.
Sal
1987 635csi (pre 6/87 build)

[cornwallis]

Have you checked the grounding at the battery, there’s a braided strap that attaches to the car’s panel frame.

What about the grounding at the starter, there’s a cable that attaches to the engine.

Do you have voltage at a Diagnostic Connector terminal 11 & ground?

[Salawada]

Have you checked the grounding at the battery, there’s a braided strap that attaches to the car’s panel frame.

What about the grounding at the starter, there’s a cable that attaches to the engine.

Do you have voltage at a Diagnostic Connector terminal 11 & ground?

I attached new ground from the negative terminal to the body of the car and checked to see that the ground from the battery is still attached to engine. Also the ground from starter to attached to the engine housing a little bit lower than the engine ground from the battery.

I will see about the voltage at 11 and ground.

I have the electronic troubleshooting manual for the 1986 csi.

But have not figured out what the plug is in the attached pic: everytime I move it the car will fire up. What role does it play in the wiring?

Sal
1987 BMW.635CSI auto

[Salawada]

This is the pic of the wiring connector that I move around to get the car to start. What is the purpose of this piece between wires. They seem to go in on one side only to be connected to another wire on the other side

[cornwallis]

I looked for similar bundle on my 1985 and posting below. The plug shown below goes into the power distribution box (with all the fuses). The yellow/black wire is tied to your ignition system. Would pull the ETM for your car, grab a multimeter and check the connections. Since it is starting just not repeatable, it’s likely a loose connection or bad ground that’s preventing from competing the circuit.

[Salawada]

cornwallis,

Thank you. I checked all the connections and found 12 v to main cable from battery to starter soleniod but only 8v from blk and yellow ignition wire to the starter solenoid.

Researched the issue and determined that perhaps when hit the wires deliver less voltage. That would explain why it starts sometimes and doesn't start other times (especially when it has been driven a while).

So i ordered a Bosch WR1 Starter Relay from Amazon. Hooked it up (although instead of trying to hook up the red power to the starter power I hooked it up directly to the positive battery terminal.)

It has started every single time for the past 5 days.( I know I have just jinxed myself)

[pgh880]

cornwallis,

Thank you. I checked all the connections and found 12 v to main cable from battery to starter soleniod but only 8v from blk and yellow ignition wire to the starter solenoid.

Researched the issue and determined that perhaps when hit the wires deliver less voltage. That would explain why it starts sometimes and doesn't start other times (especially when it has been driven a while).

So i ordered a Bosch WR1 Starter Relay from Amazon. Hooked it up (although instead of trying to hook up the red power to the starter power I hooked it up directly to the positive battery terminal.)

It has started every single time for the past 5 days.( I know I have just jinxed myself)

Hi Salawada ,

Im also afflicted by the same problem in my 1984 635CSI . I have tried the start relay as well but in my case when the tech installed it , the car started as well but it seems the starter is still continually cranking even if the engine has started or has idled already . Do you have a diagram/ instruction how you did the installation? You can PM meif your having difficuty posting it and we can communicate via email . Thanks in advance and stay safe.

Pgh880

[Salawada]

pgh880,

Here is my best sketch of the setup I used. The instructions tell you to attach the red wire from the relay to the starter solenoid in order to get power from the red wire coming from the battery. Not wanting to mess with the wiring on the starter solenoid and because it was a tight spot I instead just installed the red wire directly to the postive terminal on the battery. I then ran the yellow ground to the negative post because I checked the ground there and it was good.

Next unplug the blk/yellow ignition from the spade on the solenoid and plug it into blue relay wire. And then run the black relay wire to the same spade on the solenoid where you disengaged the blk/yellow ignition wire.

Not the neatest setup but it works for me.

[pgh880]

Thank you very much for your reply . I will ask my tech to do this .

Pgh880

[pgh880]

Hi guys ,

My tech and I we’re able to solve the problem after 14 years of ownership tackling this intermittent problem . We followed the advice of a fellow owner of a 635CSI in the bimmerforums E24 . He is from Australia. We just ran an extra wire from the terminal 87 of the start relay located underneath the dashboard and directly connected this wire to the yellow black wire connected to the starter solenoid . Lo & behold the car starts using the ignition key every time even when hot .The problem was that the yellow black wire connected to the solenoid was not getting enough current when I used the ignition switch when I start the car . I also retained the start push button switch we installed 14 years ago so that when the problem recurs I won’t get stranded .

pgh880