How to depressurize the fuel system when removing fuel pump fuse does not work?

Feb 20, 2006 4 Replies
M

Hi,



I have a problem to depressurize the fuel system for my 1988 240GL sedan as I need to check the in-tank fuel pump. According to Haynes manual, I need to take off the fuel pump fuse and start the engine, let it stall and proceed to the rest of fuel system depressurization.



But after I took out the fuses (even all the 16 fuses in the fuse panel), the engine still could not be stopped. I post the question a few days ago and from the information that I gathered, I suspect that someone has modified the electric wiring for the fuel pump, as this car was bought from someone else and it had been serviced by several mechanics.



So are there any other ways to depressurize the fuel system?



Any suggestions will be greatly appreicated.



Thanks very much.



Regards



Martin



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M

1 somebody hotwired the relay: restore to factoryspecs, as the current situation isn't safe 2 Ignore Haynes and unscrew a connection wearing goggles and with a rag wrapped around it.
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P

I was following the same advice for my 1999 V70 and probably stumbled over the same problem. The fix for me was to find the correct fuse. In V70 there is two sets of fuses: main and secondary - two locations - main is inside the engine compartment. In the main there is a fuel pump fuse.

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J

Hi,

Sorry, but I can't see the problem. In my 265, there never was any pressure in the rear, i.e. the fuel lines to/from the tank. I just popped of the hoses and got the pump out of the tank. Came a trickle just as the hoses came off, bot that's all. Remember that the in-tank pump is just a pre-pump to the main pump located just in front of left rear wheel. It's after the main pump the pressure builds, but that pressure is contained from main pump and forward and doesn't kick back, and the return hose is pressureless - more or less anyway. When the main pump stops, the pressure drops quickly to nada..

Johan

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M

How did we miss that? True - the lines at the tank have no pressure. Depressurization applies only to the fuel system between the main pump output and the engine.

Mike

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