Morning guys,

I am having difficulties with a MBZ we have here;

Vehicle runs rough at all times, mostly when warm/hot. Tested fuel pressure, found no change in cold, warm and system pressure.

Cold control = 72lbs, warm control = 72 lbs, System Pressure = 72lbs.

Checked for blocked return line, plugged WUR (disassembled, cleaned, replaced O-ring), no change. Crack the return lines and pressures wobble a bit but no real drop (1-2psi).

Day #2:

Sys Pres : 72lbs

Cold Con Pres: 65lbs

Fuel Rate: 850ml/30 sec @ 12.4V (NAPA FI book shows 1L)

Did not allow to warm up. Will remove screens in CPR and test again.

Also: If I vent the pressure at the gauge with the release, idle picks up until the pressure returns to its 65 psi.


Day #3:

Poked holes in CPR screen, CCP seems to have risen a pound or two.. could be crappy gauge or connections.

Flushed return line from CPR to dizzy and from dizzy to tank with carb clean and air- No change.

Ran engine with return line emptying into remote container- No change.

Perhaps there is blockage in the CPR return line ingress in the dizzy- Will pull and investigate.


No luck. Cleaned plunger, polished lightly on wheel as it had some considerable scoring.

Reassembled, runs worse than ever.



I am more familiar withe VW set ups, but I would assume this is very similar. On my VW's I would remove WUR, tap iron plug out a bit, tap cold start pin a bit and start setting fuel pressure from base line- However, I am reticent to start doing that on a vehicle that does not belong to me.

ANY help that could be passed along would be greatly appreciated! At this point I am a little lost..

thanks!

russ