Bought 89.5 octane fuel recently because queued before price hike to pump and pump has no 91/2 octane.1/2 tank used ok.
Charged battery prophylactically on sunday without disconnecting.
Tuesday,today car has no power on hiway,slowed down to shoulder,car stalled.Started again ,ok,car still not as powerful as before.Check this list,checked the overvoltage relay fuse,seems ok.Hesitates to put in 120C$ relay if that is not the culprit.May have to check fuel filter,supply etc,3 yrs no change since po??

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Tom 1992 300E 2.6

Check the fuse in the top of the overvoltage relay. It is located behind the battery and the plastic cover. The relay will have a 10 amp fuse and a red top. The fuse is a standard 10 amp blade fuse.

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Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

thanks,Benzmac,checked red 10A fuse,Okay.
So I guess that ruled out accidental overcharge by automatic batt.charger?

As I said,it may be the fuel supply side if that is the case.

Car seems to run fine now with a mix of 89.5 and 92 octane mix.

May take to dealer as favourite mech on holiday.

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Tom 1992 300E 2.6