1974 W115 220 fuelling problem


Aug 24, 2010
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Your Mercedes
1974 220 W115

One of the fuel hoses on my 74 W115 220 broke recently and I replaced it, along with another hose that looked a bit dodge. Shortly afterwards, the fuel pump started leaking petrol so I replaced that too.

All seems to work OK again, except that when the engine is warm and I'm travelling at a steady 40-50 mph, the engine starts hesitating and losing power. Putting my foot down and speeding up solves the problem. It's fine at higher speeds and lower speeds, and no problems at idle. It's dodgy at cold idle, but that's the automatic choke which has always been temperamental.

I don't know whether the problem is related to the fuel pump / hose problems, but I suspect some sort of crud in the fuel line getting to the carb - a Stromberg of some kind. So should I:

1. pull the carb apart looking for a blocked filter (gulp)
2. remove the carb and send it off for a refurb
3. take the whole car to my local classic MB shop, who would probably fix it but are expensive

Grateful for any advice as cash is limited, and I'm no great shakes with a spanner. The car is our main drive so I've got used to relying on it :)


Creme Eds

Active Member
Apr 19, 2010
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Your Mercedes
SLK 200
With a car of that age it's worth putting an in-line fuel filter in as near the tank as possible. It's probably got a fuel filter somewhere already (and you should locate that and see what state it's in; Might be in the pump, might be in the carb, if there's a pressure regulator it may be in there, or it may be a separate unit) but the in-line filter will give you an idea if the tank is starting to rust, put flakes into the fuel and how fast.

If there's a fuel return line make sure that's clear (blow through it!), and if there's a pressure regulator make sure that's not packed in (there'll be something about flow rates in the manual to check).


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