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Old 08-22-2017, 11:38 AM   #1
pointer80
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One more question about disabling fuel pump

hello Guy's, In a previous post I asked about fuel pump relay location for disabling fuel pump for running a compression check. Now I am wondering if I can just take out the fuel pump fuse instead of relay? Thanks all.
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Old 08-22-2017, 12:05 PM   #2
95 S_Trucker
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Re: One more question about disabling fuel pump

When doing a compression check, there is no need to do anything with the fuel pump circuit.

Take the keys out of the ignition and don't put them back in the ignition. You will not need them to do a compression test.

Use a pedal depressor(or whatever you have, board/brick) to hold the throttle open.

Use a jumper wire or a push button starter switch(specifically meant for compression checks) between the starter S terminal(purple wire) and the positive battery terminal.

This way ensures the fuel pump will not run, the injectors will not pulse, and the ignition system will not fire.
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Old 08-22-2017, 03:29 PM   #3
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Re: One more question about disabling fuel pump

Unplugging the fuse is better then unplugging the relay.

With the relay unplugged a redundant circuit that goes through the oil sender will supply power the fuel pump once the engine gets around 4 PSI of oil pressure. If you crank it long enough it should get enough pressure to make the pump run after some time.

Unplugging the fuse stops power from getting to the fuel pump. This will most likely set a trouble code 54 in the computer. The code is easy to clear and will clear its self with time.

Some people just unplug the injectors but if you do that be careful because the plastic may be very brittle and the tabs may break off.

Disable the ignition also.

The suggestion to use a push button starter switch for testing compression is the better method.
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Old 08-22-2017, 11:42 PM   #4
pointer80
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Re: One more question about disabling fuel pump

Quote:
Originally Posted by 95 S_Trucker View Post
When doing a compression check, there is no need to do anything with the fuel pump circuit.

Take the keys out of the ignition and don't put them back in the ignition. You will not need them to do a compression test.

Use a pedal depressor(or whatever you have, board/brick) to hold the throttle open.

Use a jumper wire or a push button starter switch(specifically meant for compression checks) between the starter S terminal(purple wire) and the positive battery terminal.

This way ensures the fuel pump will not run, the injectors will not pulse, and the ignition system will not fire.
Thank you for this info, One more question, why does the throttle have to be wide open if I use a remote start? Will the throttle not being fully open effect the compression check? Thank you.
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Old 08-23-2017, 11:10 AM   #5
95 S_Trucker
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Re: One more question about disabling fuel pump

When doing a compression test, the throttle needs to be open. It it's not, it will cause an air restriction, and give you false results.
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Old 08-23-2017, 06:34 PM   #6
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Re: One more question about disabling fuel pump

Thanks
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