Quote:
Originally Posted by Parrot of Doom
Fuel delivery computer? Whats that then?
How can a fuel delivery computer introduce air into the system?
Sorry for sounding cynical.
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Yeah, exactly...this sounds bad.
The very first thing I'd do is check all of the lines to make sure they are all routed correctly. It's really easy to push one into the wrong side of the lift pump or shutoff valve and not notice it.
Don't take for granted it was right when you bought it, maybe someone screwed it up before you ever saw it and you just copied their routing and duplicated the problem. Then, assuming the lines were all routed right I would check each line, one by one to make sure its o-ring was sealing right, but start on the pre-filter before you get that far.
I'd bet $10 they pre-filter o-ring is at fault. This one has caused more agitation on this car than any other part. A $0.10 part that has probably lead to more people selling these cars than any other. I'd bet $100 it's not a computer problem if you are seeing air in the lines. Find another shop or fix it yourself unless this guy is so sure that he'll not charge you if it doesn't fix it I would not approve him installing a $1200 part by the "shotgun" method.
Since essentially the entire system is under vacuum from the tank through to the lift pump any seal failure in any of those fuel lines or connections will cause air to be drawn into the fuel system. In my opinion this is the worst design MB ever came up with.
Why they would design a system that has the fuel pump located under the hood, downstream of at least a half-dozen o-rings is beyond me. It's much easier to find a faulty seal under pressure than it is under vacuum but having the pump draw the fuel through all these lines is what makes it really hard to find a failed one. That's just about the only good thing about putting a fuel pump in the fuel tank is that it eliminates the possibility of drawing air from a failed seal on the "sucking" side of the pump. This system almost invites that sort of failure by its very design.
Bottom line is this...find the failed seal and you will eliminate the problem. It could even be a blocked screen in the tank, just use logic and follow the fuel path from the tank to the IP and it will get solved.