560 FI Help

[garymand]

1990 560 SEL, Motor is in good shape mechanically with new timing chain 1k miles on chain. Car starts, idles nice, acts normal in gear for a minute then starts sputtering with throttle. Sputtering gets worse quick and soon stalls. Let it sit for a few minutes: it starts and idles fine, will start out in gear well for a few seconds, does one shift, then the sputtering, lose all power, and stall. Compression is good Spark is good. How do I trouble shoot to the probable gas failure?

[franjo_66]

Gary, have you checked whether the return fuel flow has any impediment or blockage?

I had a similar situation on a 450SE (W116). The return fuel flow had a blockage. Fixed that and everything back to normal.
Hope you find an easy fix !

Best of luck
Franjo

[stickandrudderman]

You'll need to plumb in a fuel pressure guage.

[ja17]

These W107 cars are getting older and are showing up with fuel tank contamination problems these days.  Yes, plumb in a fuel gauge or take the sender out of the tank and take a look. Change the main fuel filter.

[stickandrudderman]

Point of order:
A 560SEL is a W126 not a 107!
Not that it matters, the systems are the same.

[garymand]

Sorry, I thought I'd responded weeks ago.  It was the fuel pump power lead. I was all setup on the motor, measuring the 50% pressure ratio and walked pasted the back of the car and noticed the fp sounded strange and loud.  saw sparking at the terminal of the fp.  The nut came off! The wire terminal was bouncing around on the screw threads with motor vibration.  P ::)ROBLEM SOLVED.