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88 XJ 4.0L Maneul wont stay running

Sullie

NAXJA Forum User
Location
el paso tx
So My jeep was running fine, I redid all the vacuum line per the diagram...
f422884294f6c6a938224a5861b09a4c.gif

now when i start its stumbles for a few seconds then dies...
I have brand new...
Cap, rotor, wires, plugs, fuel filter...
checked my TPS its good, sitting at .83....
My CPS is at .5, so shes good
I dont have a vacuum line to check the MAP, but i hooked a surenge up to it and sucked and the Volts moves, plus shes new so im sure shes good...

I removed the fuel pump and double checked it, she works...

It doesn't seem to be getting fuel to the rail like it need...
I am only taking a guess but could it be the fuel pump relay (I do hear the fuel pump when i turn the key)...Or maybe the Ballast Restricter?

Please Help!
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Do the renix jeeps have a in line fuel filter? The 91-96 have a external fuel filter just a little bit away from the tank on the frame rail.

Kind of sounds like MAP to me since it was fine before, but I'd also keep o2 sensor in mind if everything on the fuel pump side is ok.


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Map is new so I doubt it's that but I will check...
Yes it has an inline filter, it's brand new too

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You can bypass the ballast with a fuse, the size for the dash fuse box, bridge the connection with the fuse wire should plug on to the fuse.

That should get you past the initial start up pressurization.





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I say ballast or fuel pump relay
 
I pulled the line off the restrictor...
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No fuel is getting to it...
I can hear fuel pump when I turn the key on...

And I put a new relay in...
Any suggestions
 
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Sullie,

Fuel pressure gauges are about $10. Money well spent.

When you did your MAP vacuum line which hole in the throttle body did you plug into? The rubber "grommet" has two apparent holes. One is a keeper that holds the grommet in place, it does not go all the way through.

If it's in the wrong hole, it'll run like poop, if at all.

And...it's real easy to bypass the ballast...just a jumper wire. That'll tell you if that's your problem
 
Map is in the btm hole...
Jumped the ballist still no start...
She's not getting fuel to the rail...
I disconnected fuel line in front of inline filter, turned the key and fuel spurted out...
Then I remo we the restrictor to see if fuel got there in the rail and nothing, no fuel in the rail....
I jumped it with started fluid and she fired right up...

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Either the filter is bad or the pump is not getting to pressure.
Unless the renix jeeps have something else in the line I don't know about.

You could rig a pressure gauge in font of the in line filter to check the pressure is there coming out of the tank.
Other than that I think there'd have to be damage to the fuel line or debris in the line before the rail.



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Three fuel supply modes. First, turn key to run and the pump primes the fuel rail for a few seconds. Second, fuel pump receives power from the starter relay during cranking. Third, CPS sends pulse signal to ECU and the CPU energizes the fuel pump relay.

Don't expect the fuel pump to continuously run when the key is is the run position, not going to happen unless the engine is running.

You'll only get continuous fuel pressure/flow during cranking or when the engine is running.

Pull the vacuum line off of the EGR and plug it, see what happens, you can hook up the EGR solenoid wrong.
 
I disconnected the vacuum lines off her and plugged still no start...
When I depress the fuel rail pressure valve I hear no pressure... this tells me the fuel pump isn't pushing enough pressure to fuel rail...

I pulled the line off, just before the fuel filter and turned key over, it's priming past the fuel filter just not making it up to the fuel rail
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I want to pull this line off and turn key to see if fuel is making it this far, but can figure out how to release it
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So I got the line off, lowered it under the truck, turned the key and wala fuel came out into the bucket....
I raised it back up to it's proper height and location and turn the key, no fuel....
At this point I'm assuming fuel pump isn't pushing enough to get fuel up the line

I did remove the fuel pump the other day cause I suspected the 2in plastic pickup line came off, and it did, I reconnected it and she worked for a while, now these fuel pump issues...

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Decided to repull the fuel pump and assuming this might be the cause for it not pushing fuel all the way up to rail...

Could this cause it and stil squirting fuel past the filter, with 1/2 tank of fuel
eb06b3b00dd0fe7c1c9503b1dc42bcba.jpg


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Last edited:
Decided to repull the fuel pump and assuming this might be the cause for it not pushing fuel all the way up to rail...

Could this cause it and stil squirting fuel past the filter, with 1/2 tank of fuel
eb06b3b00dd0fe7c1c9503b1dc42bcba.jpg


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With that hole up at the output of the pump it can't build enough head pressure to get the fuel up and to the rail sense mOst of the fuel is just bleeding off before the line leaves the tank. Properly fix it or get a new pump.


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I fixed the line, reinstalled and doesn't seem to be pumping now, getting power back there...
Going to remove and check internal connections

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I fixed the line, reinstalled and doesn't seem to be pumping now, getting power back there...
Going to remove and check internal connections
Laughing with you Sullie, laughing with you. I'm not the only one... :laugh:
 
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