Re: No gas pressure (archive)

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In Reply to: No gas pressure posted by Ed Scott on November 18, 1999 at 03:40:06:

: My car runs extremely well at idle and speed, but I am going crazy over a starting problem. When I first start the car in the morning, it takes two to three seconds to start, and misses for another 2 - 3 seconds before running smoothly. Then all is fine.

: I have run 2 - 3 cans of Techron injector cleaner through the system to no avail. My fuel system seems to not hold pressure more than 30 minutes after shutting down the engine. Can you help?

: Question - does the gas from the tank enter the fuel rail at the regulator or at the fitting near the firewall? When I remove the gas line at the regulator after just a minute or so after shutdown there is no pressure at all. No gas even comes out of the line. Does this indicate the regulator is faulty?

: Is there another pressure unit or check valve in the fuel line? If so where? I have heard from local sources that there is one in the fuel pump. If there is one in the pump and it is faulty, can I insert a check valve in the line?

There is, indeed, a check valve at the pump outlet. Some VDO pumps have a thread off, replaceable check valve (like Jaguar which uses a pump that appears otherwise identical to the one installed on Bimmers), but most VDO pumps installed I've seen on BMWs have a non-removable one installed at the pump outlet neck.

Quite often they jam open from a small contaminant that made its way from the fuel tank, and simply removing the pump and running it a few seconds dry (a FEW seconds only as they are fuel-cooled) frees up the valve. It's worth a try.

I am not sure if you can fabricate an in-line check valve, but if the pump is good, it seems like a reasonable alternative to a $170 pump replacement.

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