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IM so mad it wont start

B

blu3fan

NAXJA Forum User
Location
Arizona
Jeep died again
92 4.0 aw4.

fuel pressure issue.

first.
would get 40psi on rail.
go to start.
0 psi.

replaced fuel pump.
when I removed it. was not pumping.

found blocked fuel line.
blew out with air.

now with new pump it starts. but psi drops to 20 upon starting.
then drops to 15.

0 fuel in return line.
does this mean regulator is bad ? or injector leaking ?
 
Okay. did some more testing.
I tried to fill a bucket from the fuel filter. on the new pump. same issue as old pump.
I do not hear it whine like it did.
after a few key turns a i had a steady stream
but nowhere near enough.
possible voltage issue ?
 
okay. jumped the relay. pump does not make a noise.

going to get a voltmeter later to test. but right now it seems like there may be an electrical issue
 
I am going to just wire the battery to the pump. it if runs im going to jerryrig the heck out of it. Fuel pump on switch lol. until I can figure it out.
 
Just to confirm.
When jumping the relay. should key be on or off ? or doesnt matter. I wouldnt think would matter but im getting no noise from the new pump now.
 
I should probably note.

ALL FILTERS ON OLD PUMP WERE CLEAN. As was the inline filter.
I do not know what debris was in fuel line. or if it was causing a real issue. but i blew down the line. felt resistance. and shot compressed air down there. now its clear.
 
blu3fan said:
Okay. did some more testing.
I tried to fill a bucket from the fuel filter. on the new pump. same issue as old pump.
I do not hear it whine like it did.
after a few key turns a i had a steady stream
but nowhere near enough.
possible voltage issue ?
Click to expand...

A bad ballast resistor can cause low voltage/amperage to pump. Jump it and see what happens.

Do a volt test at pump, ohm the ground. I've had corroded ground rings on mine cause issues, also had a bad connector another time. Ballast resistor is the most common trouble spot.

You can blow backwards through the filter and see what comes out, rubber chunks is a dead giveaway.

Fuel line plugs are often gelled fuel. It may take a few tries to clean it all out. I periodically add a can of fuel injector cleaner in my tank, the solvents seem to deal with gelled fuel fairly well.

I used my solvent gun (with a little jury rigging) and a quart of acetone to clean my lines out. I was amazed at how much stuff came out of there.
 
So can anyone confirm.
I had the key off when I used a paperclip to connect 87 to 30* I think those were the ones I did. front and rear ports on the relay

did I need to have the key on ?
I would have figured fusebox has power regaurdless.


other reasons I am thinking it is the ground.

Every time I messed with it under the car by the pump I got better or worse.
Could be that I was jiggling the loose ground.

when I get home I will check it.
My #1 suspect is the ground.
 
bad ballast resistor could also make sense. so I will bypass that as well.


*Edit.
reading more things saying a bad ground in the fuel pump power system can cause the ballast resistor to burn out.

this would explain the low fuel pressure.

so maybe bad ground and resistor. not sure yet.
Ill be home in 10 hours to check.
Will get back with more info,
 
Bypassed ballast. She lives. 50 psi at the rail solid. All my idle issues from the last 7 years are gone. Thank you so very much.
 
ill get a pic up tomorrow. but as soon as I removed the terminal I knew it was the ballast.
terminals are green with corrosion.
 
Damn. It's almost never the ballast with these problems.

We've still got a intermittent start up issue, where it stalls on the first start up of the day but runs fine otherwise. New ballast, by pass ballast, replaced Idle Control, and dozens of other little things. Still no clue what causing it.


Sent from my iPhone using Tapatalk
 
Green Mesa XJ said:
Damn. It's almost never the ballast with these problems.

We've still got a intermittent start up issue, where it stalls on the first start up of the day but runs fine otherwise. New ballast, by pass ballast, replaced Idle Control, and dozens of other little things. Still no clue what causing it.


Sent from my iPhone using Tapatalk
Click to expand...

Checked the fuel pressure regulator ? this was what mine was doing before I changed that.
 
blu3fan said:
Checked the fuel pressure regulator ? this was what mine was doing before I changed that.
Click to expand...



I changed it once, awhile ago now , but I think I've got another in a box someplace. Might just swap it one day to check because it's not on my radar.
When it stalls the few instances I was able to get a fuel pressure gauge on it the pressure looked good, but beginning of the day, low vacuum, maybe a good place to revisit. Thanks!
 
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