Fuel Shut Off Help

[rvanbeers]

2003 Expedition Eddie Bauer. I have spent many hours trying to find our how to shut off the fuel pump/disable the fuel as I'm trying to do a compression test on one cylinder. I had a relative compression done and it was greater than 40% on one cylinder. I just want to compare 3 easy access cylinders

You can't pull the relay as it is part of the fuse panel. I have located the inertia but there is no switch and only a reset button. This is driving me crazy.

Any help on how to disable the fuel/ignition is greatly appreciated.

 

[toms89]

There should be a fuel pump fuse in addition to the relay?! Its number 10 in the under fuse block in a 2000.

You should also hold w.o.t. while doing compression check and this will keep it from injecting fuel as it is in clear flood mode.

Then you could always unplug the crankshaft sensor and it would keep it from starting, injecting fuel, etc..

 

[1997SCEBFEX]

You can't pull the relay as it is part of the fuse panel. I have located the inertia but there is no switch and only a reset button. This is driving me crazy.

Any help on how to disable the fuel/ignition is greatly appreciated.

I disconnect the wiring harness from the inertia switch when servicing (changing fuel filter) and also pull the fuse on my aux fuel pump as it will keep running.

Hope it helps.

 

[rvanbeers]

Thanks for the Response. Not #10 fuse on the 2003. Relay 203 (PCM) #32, 33,34 is the Fuel Pump Relay, PCM and sensors. Relay 303 is Fuel Pump shut off but that relay doesn't exist.

I'll try the crank sensor if I can locate it.

 

[Thermo]

rvanbeers, for my 97, all I did was create a small jumper with a switch in it that I went from the battery side of the starter solenoid to the ignition post on the starter solenoid. This does not supply power to the ECM like it does if you rotate the key which then prevents fuel from being injected into the motor. That way you are also controlling everything from the engine bay.

 

[toms89]

A remote starter switch allows you to do a compression test with out a helper.
If you do not want to make one you can get them pretty cheap from almost any auto store.

Actron CP7853 Remote Starter Switch : Amazon.com : Automotive

 

[GAINMOB]

the shut off switch is in the driver side rear panel...you should see a knob on the panel thats the cover for it and a little compartment...in the rear cargo area

 

[rvanbeers]

the shut off switch is in the driver side rear panel...you should see a knob on the panel thats the cover for it and a little compartment...in the rear cargo area

Thanks everyone for the info. The fuel inertia in the back seems to be a reset only button with nothing to turn it off or at least I can't find it. Pressing down does nothing. Anyhow, unplugging the cam sensor worked.....it was all for not because I couldn't get the compression tester to thread in the plug hole. My guess is you need a longer thread attachment..... I've spent $500 bucks for a dealer and other centre to do electronic analysis and all I know is I have a missfire and bad relative compression on the one cylinder (which in all honesty I don't understand accuracy of relative compression or if something like a bad COP or PCM would trigger false results). I'm about to give up on this expy and send it to the auction.

There is no oil burning or coolant loss, engine sounds smooth but shakes a little at idle. The shake increases underload and will set a P0 175 (Rich on Bank 2 - same side as Miss Cylinder). Changed plug, tried now COP changed injector). The plug was a little wet with gas when I pulled it again. The question is now should I spend another 120 bucks to do a leak down test only to potentially learn the engine is toast.

 

[toms89]

Thanks everyone for the info. The fuel inertia in the back seems to be a reset only button with nothing to turn it off or at least I can't find it. Pressing down does nothing. Anyhow, unplugging the cam sensor worked.....it was all for not because I couldn't get the compression tester to thread in the plug hole. My guess is you need a longer thread attachment..... I've spent $500 bucks for a dealer and other centre to do electronic analysis and all I know is I have a missfire and bad relative compression on the one cylinder (which in all honesty I don't understand accuracy of relative compression or if something like a bad COP or PCM would trigger false results). I'm about to give up on this expy and send it to the auction.

There is no oil burning or coolant loss, engine sounds smooth but shakes a little at idle. The shake increases underload and will set a P0 175 (Rich on Bank 2 - same side as Miss Cylinder). Changed plug, tried now COP changed injector). The plug was a little wet with gas when I pulled it again. The question is now should I spend another 120 bucks to do a leak down test only to potentially learn the engine is toast.

I have never had an electronic relative compression test performed but my best guess is it determines how much each cylinder contributes to the power output. If this is the case then a misfiring spark plug, faulty injector, etc... could effect it. For instance if one injector does not spray a fine 30 deg conical mist but sprays a stream of fuel.... that cylinder may not contribute to the power output as well as the others as the fuel atomization is not as good.

Again I do not know the specifics of the relative compression test so just speculating.

I have done compression and leakdown test before. Leakdown test is best to identify where the problem lies if indeed there is a mechanical issue but requires use of an air compressor. It will tell you nothing as far as fuel and ignition.

You are correct about the inertia switch. It only "trips" when you are in an accident or it senses high g force. Resetting it does nothing unless it has tripped.

 

[CandyGram4Mongo]

I
You are correct about the inertia switch. It only "trips" when you are in an accident or it senses high g force. Resetting it does nothing unless it has tripped.

I just "activated" mine tonight to relieve the pressure in the fuel line so I could change my oil filter.

I pressed it to see what it "felt" like, then hit it gently with the handle of an umbrella. (It was sitting there in my cargo area, I suppose I could have used the heel of my hand as well). I didn't have to hit it hard, and it "tripped" because when I pushed it again, I felt it click/reengage. So I hit it again, and just felt the top of the switch, and could feel that it had tripped.

I cranked the engine to start and it wouldn't, indicating that the switch was activated, and fuel shut off.

Hope this helps.