deanres

Electric Fuel Pump Failure on the Way Home

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So on my way home from work last night the 1974 2002 started to sputter and finally died. I glided to the side of a very busy road and started thinking. After pushing the car half a block in 90 degree heat and humidity I got it on a side street where I could open the trunk and listen for the electric fuel pump. Not a sound.... This was actually a good thing since I just happened to have another fuel pump from a long forgotten project a few years ago. So on the side of the road I replace the fuel pump and although a bit sweaty, with just twisted wire connections I was back on my way. This weekend I will get some proper automotive wire connections for all of the ones I McGyver'd to get going again. I noticed an in-line fuse in that hot power wire. Does anyone know if that needs to be there? 

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Extra protection against possible short circuits, but then you need to carry spares to avoid pushing your car in the heat if the fuse blows.  You should think about a roll-over/impact kill switch from a Ford to stop your pump from pumping in case of a crash.

 

Mark92131

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I would further suggest using a circuit that only provides power while the engine is running. That way in the event the motor dies (crash, seize, etc.) the pump stops running.

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The circuit does cut off with the engine and ignition, and I guess if the fuse fails I can just splice around it if I have to... 

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TOTALLY AWESOME !!  Another fantastic testimony to the all-mechanical car that, with a bit of reasonable/thoughtful troubleshooting and the right part(s), is back on the road in very short order.

 

Cheers,

 

Carl

 

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andreb,

 

how does one provide a powered electrical circuit that knows when the engine is running, or not running ??  

----  More specifically:  if sending that power to the electrical fuel pump, which if not running, the engine doesn't run ??

----  Thus, if the engine isn't running, how will the electrical fuel pump circuit ever become energized in order to get the engine running so that electrical power can flow to the fuel pump ??

---------  in other words, how does one ever get the car started in the first place, since the engine isn't running and power cannot get to the fuel pump ??

 

"electricals" are quite a bit of a mystery to me.

 

Cheers,

 

Carl

 

Edited by OriginalOwner

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1 hour ago, OriginalOwner said:

andreb,

 

how does one provide a powered electrical circuit that knows when the engine is running, or not running ??  fuel pump ??

 

 

What he (andreb) may be talking about is circuit which senses oil pressure via a sender; when the oil pressure is below, say 15 lbs (like when the engine stops turning), the sender 'switch' triggers a relay which shuts off the +12v going feeding the electric fuel pump. And there are other methods... -KB

Edited by kbmb02
Edit.

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2 hours ago, OriginalOwner said:

TOTALLY AWESOME !!  Another fantastic testimony to the all-mechanical car that, with a bit of reasonable/thoughtful troubleshooting and the right part(s), is back on the road in very short order.

 

Boooo!  This is the modern age of complexity and unreliability.

 

2 hours ago, OriginalOwner said:

----  Thus, if the engine isn't running, how will the electrical fuel pump circuit ever become energized in order to get the engine running so that electrical power can flow to the fuel pump ??

---------  in other words, how does one ever get the car started in the first place, since the engine isn't running and power cannot get to the fuel pump ??

  Maybe a circuit parallel to a starting circuit similar in function like the coil ballast system for engine start using an ignition start position to pull in the relay.  Of course, the system has to be primed so lengthy cranking is avoided (fuel wise, I mean).  Once the engine fires and oil pressure switch closes the run circuit is active.

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Jimk has the general idea. I do have sidedraft Webers on my car so priming the fuel bowl is rarely needed. I have wired in a manual fuel pump switch for just this scenario though. There are oil pressure switches that do just this. They close a contact when pressure is applies and that in turn triggers a relay that supplies voltage to the fuel pump. Using the start side of the coil ballast can work for priming and then other circuit can take over. There is also a log of the v-reg I think that closed when the alternator is supplying voltage that could work as well. That follows the logic that is the alt. is spinning then the engine is running. In most race cars we run a manual switch and sometimes add a tip-over switch for safety, sometimes required by the racing org.

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