Follow-up on M50 studdering. Solved!!, With pics...... [Archive]

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Dave M

01-19-2007, 09:03 PM

So, I believe I have found the source of my M50 studdering issues (http://www.bimmer.info/forum/showthread.php?t=28566&highlight=DME). If you don't want to read the old post(s), I'll just say that the engine would cut out periodically while warming up. It felt like no spark or fuel for a split second. I swapped a bunch of sensors/ICV/MAF/DME/Coils etc., tested the battery/alternator, to no avail. All of this, mind you, at minimal cost as Ryan R. supplied plenty of spare bits.

Starting to losing hope, I began playing with fuel delivery. I made one of these for a few $$. Thanks to whomever provided the blueprint. I've noticed quite a few similar issues lately (poor idle, engine cutting out etc.). Maybe this can help someone.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00505.jpg

And set it up to run the pump

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00502.jpg

While it was running I wiggled the connector and noticed it would cut power to the pump. I pulled the connector off and noticed a nice collection of corrosion and $hit on three of the five wire terminals, including the power supply terminal (bottom, left of connector). Sorry, hard to see with the crappy pic.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00512.jpg

Dave M

01-19-2007, 09:04 PM

Continued:

My 'schematic' of the connections, so I wouldn't forget when re-assembling. The "Large Gr/Vi" is the power supply. Bentley does not provide this tidbit for some reason.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00514.jpg

All cleaned up, new generic connectors, ready to go.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00518.jpg

So why not tear the front end apart?

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00531.jpg

Thanks to all who helped out,

Dave M

Blitzkrieg Bob

01-19-2007, 09:07 PM

You've battling this for some time.

BillionPa

01-19-2007, 11:13 PM

your fuel sending unit looks like ****!

bigtisas

01-20-2007, 01:10 AM

Good job. Where is that rusty connector located? I couldn't tell from the photo.

BillionPa

01-20-2007, 03:48 AM

its the fuel sending unit, feeding power to the pump and sending fuel levels back to the dash.

Dave M

01-20-2007, 08:38 AM

Good job. Where is that rusty connector located? I couldn't tell from the photo.

The rusty/crudded terminal is at the end of the green/violet wire in the 1st and 2nd photo of my second post. Easily visible in the 1st photo, which shows its location on the connector.

Dave M

01-20-2007, 08:40 AM

your fuel sending unit looks like ****!

As there was a tiny bit of paint flaking and surface rust forming on the tank around the sending unit, I applied a generous dose of POR-15. I'm not exactly carefull when using the stuff :D

ryan roopnarine

01-22-2007, 08:57 AM

oh wow, that fuel pump lid doesn't look healthy at all! good that you got it fixed.

Dave M

01-22-2007, 11:15 AM

oh wow, that fuel pump lid doesn't look healthy at all! good that you got it fixed.

Yeah, I was surprised how rusty the sucka is. Its likely one of the rustiest parts of the car, but it works, so who am I to judge. May have been in there for several 100k kms.

Hope you like Big Turks.

Dave