1974 450SL Roadster/ No power to fuel pump - Mercedes-Benz Forum

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post #1 of 2 (permalink) Old 05-05-2010, 10:42 AM Thread Starter
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1974 450SL Roadster/ No power to fuel pump

Has anyone ever had this problem and if so how did you resolve it.

When ignition switch is on i have no power to the fuel pump.

I tested the fuel pump (+) with my digital multimeter and no power.
i pulled off the ground wire, cleaned it and reinstalled it.
i tried the turn key test to see if the fuel pump relay was working, and i can hear it switch when i turn the key on.
i went ahead and purchased a new fuel pump relay and installed it just in case and still, no power to the fuel pump.
i traced a single wire from the fuel pump all the way to the fuel pump relay and there seems to be no breaks in the wire.
With the fuel pump relay removed and the iginition on, i tested to see if there was in fact, power getting to the relay block. and there is power to terminal #86 and terminal #87a.
So now that you have an idea what i have already checked, my question is, if i am getting power to the relay block and am not getting power to the fuel pump relay terminal 87 (which leads to the fuel pump), what could possibly be cutting off power to my fuel pump?

I did try jumping the battery directly to the fuel pump and the fuel pump did go on so i also know the fuel pump works.

Last edited by rwag; 05-05-2010 at 10:46 AM.
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post #2 of 2 (permalink) Old 05-05-2010, 11:10 AM
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Have you tested to see if there is power to terminal 87? If there is, have you tried to jump from terminal 87 directly to the pump?
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