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Possible solutions-stumbling between 4500-5500 RPM (archive)
[ Follow Ups ] [ 5-series (E28) Message Board ] [ Msg. Board FAQ ]
Posted by Pat Hines on May 06, 2001 at 12:23:13:

In Reply to: M535i is still stumbling between 4500-5500 RPM posted by Duke on May 06, 2001 at 06:06:17:

Duke,

This almost certainly a fuel flow issue, and can be only a few problems. Restrictions to flow in the supply lines, insufficient pressure, or a faulty injector(s). There are methods to test each of those components in the factory maintenance manual.

It's remotely possible that your AFM isn't fully functional, but that's unlikely since it should be fully open above 3500 rpm. Have you verified that it has no problem opening completely?

Pat

Hello All,
Have replace fuel tank pump, main pump, new fuel filter, spark plugs, valves adjusted. Still have the annoying flat spot at 4500 rmp. Does not run anywhere close to red line strong above 4500 rpm. Any suggestions? How do I check if the fuel regulator is good, it looks new?

Thanks,
Duke
85 M535i


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