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Fuel pump fuse and relay


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#1 Whisslaren

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Posted 27 April 2012 - 01:35 PM

Hi people!

I´m having trouble with the fuel pump on my -88 4.0 manche
Which fuse is it the pump uses, and also, which relay?
I´m lacking a bit on dokumentation, as you might suspekt.

Any pictures would be awsome :D

Thanks in advance!
Daniel
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#2 ParadiseMJ

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Posted 27 April 2012 - 03:56 PM

Here are the relays in the "relay center" labled.

Posted Image

I thought this might be from the 90 XJ I don't see a fuel pump fuse here...but it is from my 88 MJ...no rear wiper fuse either

Posted Image

AFAIK there is no fuse for the fuel pump in this block...there may be a fusible link at the starter relay byt I don't know which one it is.

There is a shared ground behind the drivers side taillight that is used by the fuel pump...pop out your tail light and see if there is a ground (black wire) in the bucket screwed to the sheetmetal . Shine it up and replace. They do get crusty back there.

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#3 Optimaldave

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Posted 27 April 2012 - 06:33 PM

^^^^ correct

No fuse, but uses a fusible link at the starter relay. Center relay, though in my 88 pioneer there were only 3.

Have you tested for power or just guessing it is electrical?
If so where is it losing power or is the whole circuit dead?
Can you hear the pump prime when you turn the key to "on"?
Swapped the relays or jumped from the battery + to the + on the pump relay socket?

I've just gone through replacing my pump and some electrical diagnosis with mine too...

Cheers
Dave

#4 Whisslaren

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Posted 28 April 2012 - 06:37 AM

Thank you guys! That was really helpful.

Last time it ran it was when I moved it so that I could lift of the bed. Everything was already loose from the bed then. But it was hard to start, so I think I´m starting with the ground.

Another quick question. The fuse that says haz/stop, whats it for? It´s shorted, but I haven´t paid it much attention since it doesn´t seem to have anything to do with drivetrain running.

Cheers
Daniel

#5 Geonovast

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Posted 28 April 2012 - 06:39 AM

The main ground for the fuel pump is behind the driver's side taillight. I would start there.

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#6 cruiser54

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Posted 28 April 2012 - 07:20 AM

Here are the relays in the "relay center" labled.

Posted Image

I thought this might be from the 90 XJ I don't see a fuel pump fuse here...but it is from my 88 MJ...no rear wiper fuse either

Posted Image

AFAIK there is no fuse for the fuel pump in this block...there may be a fusible link at the starter relay byt I don't know which one it is.

There is a shared ground behind the drivers side taillight that is used by the fuel pump...pop out your tail light and see if there is a ground (black wire) in the bucket screwed to the sheetmetal . Shine it up and replace. They do get crusty back there.


Just so ya know, it's a real good possibility the relay illustration is wrong. As in they have the relays listed backwards.

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#7 ParadiseMJ

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Posted 28 April 2012 - 03:55 PM

In that case...use a mirror. :brows:
It is set up this way on my 88 Pioneer and the 90 XJ Laredo.

1988 MJ 4.0 SWB  D30/D44 LSD

Northern Sierra/Southern Cascades

 

OurChristmasTree.jpg

 

 

Nevermind, just saw you're in Communist California...

 

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#8 cruiser54

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Posted 28 April 2012 - 03:58 PM

In that case...use a mirror. :brows:
It is set up this way on my 88 Pioneer and the 90 XJ Laredo.



I checked my 90 MJ last night and if you use the starter relay as a reference, the posted illustration is bass-ackwards.

Cruiser's Mostly Renix Tips (over 25 of them) can be found here:

 http://comancheclub....ers-renix-tips/

 

 

Refresh*Connections*Before*Replacing*Components

 

My Jeep Technical photos can be found here:

 

 


#9 Whisslaren

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Posted 29 April 2012 - 12:50 PM

The ground wire it was! :D

I think the reason it still ran when all the wires were disconnected is that somehow there is still some ground left. I could still measure resistance enough to make it fishy, but small enough so that it would run if it wanted to, even with the bed completely off, as it is now.

So what it all boils down to is probably mourning. The day the manche stopped starting was the same day my WJ diesel made it´s last breath just a couple a meters from it. (Crank seized, only available jy engine 4000$, so I´m trading it as is for a overhauled old policevolvo)


Thanks for the help guys! Really helped me cut down faultfinding time.

Cheers!