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CRANK NO START (I have read all the other forums on this topic)

E28 technical advice asked and given! Troubleshooting, modifications and more.
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FreddyL
Posts: 4
Joined: Jan 15, 2025 1:13 PM
Location: New york

CRANK NO START (I have read all the other forums on this topic)

Post by FreddyL »

Hi everyone, working on my 1986 535i with crank no start. It’s been this way for too long I want to drive my car again. Just wanna start by saying I’ve read and tried every single diagnosis discussed for this already. New flywheel reference sensors, new dme, new coil, new coolant temp sensor. I’ve ohmed and checked for continuity in every wire to the dme as well as checked that all grounds have little to no resistance. I started with a new fuel pump and filter as well. I bypassed the obc, checked and swapped out every relay possible. It will crank all day without even trying to sputter. There’s no spark or injector pulse and I can’t find any reason as to why. 
Any suggestions or additional ideas would be great, thank you.
Mike W.
Posts: 27513
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Mike W. »

First, double check that the main relay is the correct main relay and in the correct spot. I know, I know, you're sure, but do it anyway, it's unique and has to be in the right spot, it's fooled others before.

Next check either by visually inspecting the flywheel or checking for a voltage on the reference sensors, and of course making sure they're in the right spot. Voltage generation can be checked with a meter, though I don't recall how, but search, it's here somewhere, or perhaps in the Bentley manual. M/T's very rarely, but have, lost the tab on the flywheel. Autos have done it many times. Where are you checking for spark, at or just off the coil, or at a spark plug connector. Caps and rotors do go bad and can cause a hard no start, especially rotors.
FreddyL
Posts: 4
Joined: Jan 15, 2025 1:13 PM
Location: New york

Re: CRANK NO START (I have read all the other forums on this topic)

Post by FreddyL »

I will double check the main relay. The pin on the flywheel is good I forgot to mention that. I both got eyes on the pin and put my multimeter on the reference sensor when it was cranking. At separate times lol. Any idea where I can buy a new main relay? Frustratingly everything is looking good 

just to double check, which is the main relay? The box is my car is messed up from the previous owner nothing is mounted as it should be.
Fanclutchnut
Posts: 178
Joined: Jan 05, 2021 7:32 PM
Location: Westchester Co NY

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Fanclutchnut »

Could it be a bad ignition switch? It’s making connection for the starter contact but not the run? 
FreddyL
Posts: 4
Joined: Jan 15, 2025 1:13 PM
Location: New york

Re: CRANK NO START (I have read all the other forums on this topic)

Post by FreddyL »

The coil has power with key on so I think the switch should be good.
Aldo525
Posts: 458
Joined: Mar 24, 2021 3:04 PM
Location: Puerto Varas, CHILE

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Aldo525 »

Did you read this??...maybe some new check points here. Also have a picture of where the Main Relay is.

tech/rods_pages/id22.html

 
Mike W.
Posts: 27513
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Mike W. »

Main relays even from the factory don't always seem to be mounted in the same place, but I think always hanging off the side of the fusebox. Critical things about it are it has 5 terminals with numbering of 30, 85, 86 and 87, 87. Rarely there will be an 87b in place of one of the two 87's. But if there is an 87a, it's the wrong one. Wires should be, a heavy red, 30. Small green, 86. Small brown, 85. Medium red/blue, 87. Two wires, small red/white and large red/white, 87.

Part number seems to be variable, but includes, 0332019109.
https://www.fcpeuro.com/products/bmw-mu ... 0332019109

One of the problem with part numbers is there are BMW part numbers and Bosch part numbers. BMW numbers often get superseded by a new one. Same, to us at least, part, but different number.

Link to schematic, http://wedophones.com/BMWManualsLead.htm
FreddyL
Posts: 4
Joined: Jan 15, 2025 1:13 PM
Location: New york

Re: CRANK NO START (I have read all the other forums on this topic)

Post by FreddyL »

I bypassed all the relays last night and no difference. Just cranking
Aldo525
Posts: 458
Joined: Mar 24, 2021 3:04 PM
Location: Puerto Varas, CHILE

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Aldo525 »

Ignition wiring is new???...cap and rotor (as Mike said before)????... maybe you already saw this Electrical Troubleshooting manual, maybe not:

https://e28goodies.com/wp-content/uploa ... e28_86.pdf
Comfyboyz
Posts: 34
Joined: Aug 08, 2022 9:21 PM
Location: Maine

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Comfyboyz »

Got compression? Spark?
jimoreno
Posts: 1600
Joined: Aug 30, 2007 9:31 PM
Location: Land O Lakes, FL

Re: CRANK NO START (I have read all the other forums on this topic)

Post by jimoreno »

Comfyboyz wrote: Jan 16, 2025 9:49 PM Got compression? Spark?
I guess you didn't read the part where it says it doesn't Crank. No spark plugs installed.
jimoreno
Posts: 1600
Joined: Aug 30, 2007 9:31 PM
Location: Land O Lakes, FL

Re: CRANK NO START (I have read all the other forums on this topic)

Post by jimoreno »

So I was going to remove the transmission thinking that it was an issue with the aftermarket flywheel but I peeked under the car two days ago (had to step away from it to discharge all the negative energy! 🤣) and I can see the starter gear near the flywheel. Since I work alone I got a remote starter button from Amazon this morning and got under the car again and saw that the starter moves and engages but no movement at all. I linked a short video of the only movement so far. I can turn the engine with a ratchet with some difficulty but it's possible. Next I'm going to get the torque wrench and see if I can determine the actual torque needed to turn.
https://youtube.com/shorts/tYYHPoLkN-U? ... 3qZm_uA5W8
Mike W.
Posts: 27513
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Mike W. »

jimoreno wrote: Jan 19, 2025 12:02 PM
Comfyboyz wrote: Jan 16, 2025 9:49 PM Got compression? Spark?
I guess you didn't read the part where it says it doesn't Crank. No spark plugs installed.
I think we've got two different threads mixed in together here. Title by OP says Crank, No Start, but jimoreno is now just saying the opposite about his car, I think.
Comfyboyz
Posts: 34
Joined: Aug 08, 2022 9:21 PM
Location: Maine

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Comfyboyz »

Mike W." wrote: Jan 19, 2025 1:43 PM
jimoreno wrote: Jan 19, 2025 12:02 PM
I guess you didn't read the part where it says it doesn't Crank. No spark plugs installed.
I think we've got two different threads mixed in together here. Title by OP says Crank, No Start, but jimoreno is now just saying the opposite about his car, I think.
What a fuckin asshole 🤣
jimoreno
Posts: 1600
Joined: Aug 30, 2007 9:31 PM
Location: Land O Lakes, FL

Re: CRANK NO START (I have read all the other forums on this topic)

Post by jimoreno »

Sorry guys, I just realized that I thought this was my "No Crank, No Start" thread. I guess my desperation is making me read things the wrong way.
My apologies!
jimoreno
Posts: 1600
Joined: Aug 30, 2007 9:31 PM
Location: Land O Lakes, FL

Re: CRANK NO START (I have read all the other forums on this topic)

Post by jimoreno »

UPDATE: My "new" starter was bad as the solenoid extended but it didn't turn. After installing my old starter that turned out to be good, the engine cranks very well. Now I have no spark and no fuel so it sounds like the main relay is not getting power. Now to troubleshot!
Thanks to everyone that provided some ideas in what to look for!
Reno
Posts: 12
Joined: Apr 24, 2025 11:15 AM
Location: Corbais

Re: CRANK NO START (I have read all the other forums on this topic)

Post by Reno »

In case you already checked everything to no avail, make sure you don’t have any air leak in all those intake manifold hoses. If there is one, everything else can be fine, you will get a crank no start situation. Special attention is needed to those two lines (driver side) that go from the intake manifold to the brake mastervac. They are often cracked inside but the fabric around makes it close to impossible to notice. The big right angled intake hose (air filter-->airflow mass sensor) also often cracks underneath. There are connectors on it wich might not seal properly with possibly other dryed out vacuum hoses.
Just my 2c.
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