Old R129

[hoochini]

It'is an older girl 1992, 125K on the clock - sometimes when I try to "give it some beans" it seems to have a problem getting into revs, it sounds as the fuel pump straggles with fuel delivery. Don't get me wrong when I drive, it goes pretty well but from time to time when I want to get started from the stand still with a bit of umph it staggers. Is it possible that it does not get enough fuel (fuel pump?) or maybe too much of it (injectors)...?

Any suggestions?

 

[grober]

As a 500 it may have dual fuel pumps plumbed in series. One may have failed. You will have changed the inline filter?

 

[hoochini]

fuel filter looks brand new... should I change it anyway?

 

[grober]

fuel filter looks brand new... should I change it anyway?

The alloy can [body] of the filter usually looks pretty clean- without knowing the cars service history its difficult to know from visual inspection. Other possiblities are a blocked tank vent or debris blocking the tank outlet filter.
That's assuming that the fuel pressure is the problem?? Sure way is to get a pressure gauge on to the fuel distributor test port and monitor it over the rev range

 

[slsteve]

Are you sure its not electrical? If it is misfiring, check inside the distributer caps for moisture/condensation, common m119 issue. Give the caps and rotors a good clean with WD40 and smear some silicone grease around the cap seals before reassembly.
Hope this helps.

 

[hoochini]

I have exchanged all electrical bits with new, new distributors, spark plugs, leads and capacitors. and checked them just couple of weeks ago...