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

[Dave M]

So, I believe I have found the source of my M50 studdering issues. 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.



And set it up to run the pump



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.

[Dave M]

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.



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



So why not tear the front end apart?



Thanks to all who helped out,

Dave M

[Blitzkrieg Bob]

You've battling this for some time.

[BillionPa]

your fuel sending unit looks like ****!

[Dave M]

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

[ryan roopnarine]

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

[Dave M]

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

[bigtisas]

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

[Dave M]

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.

[BillionPa]

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