Same old fuel pump woes

studiousjames

New member
Hello there and thanks for letting me in
New to the whole thing, a member suggests i post my issue here.
Here goes.
1989 Cherokee Sport 2 Door. 1633k miles. 4.0 unmolested.
New timing chain, gears, etc. from shop 1k miles ago. All engine sensors, coil, plugs, wires, dist, cap, rotor, I have around 160 on every cylinder with less that 4 lb variance between any 2.
. All new injectors, fuel pressure reg, new pigtail ends for injectors,
new brake booster, master cylinder, calipers, shoes, hoses etc.

K....
this thing runs boss. Seriously awesome. Only issue is it keeps eating fuel pumps. New lines, all the grounds check out. no problems at all.
Tried an airtex, then Delphi pump. No good.
I saw some threads here before I joined on how to rig an external inline pump. I just need to know how many psi that pump needs to produce. It seems that the Renix needs about 40psi or so. But all the inline pumps I can find max at like 4psi?
can someone steer me in the right direction?
Thanks again for reading and adding me. This really is the very Jeep I have always wanted.....
 

tech1001

New member
What's happing to the pump ? is just going dead or burning up ? have you checked the relay that runs the fuel pump . I know some XJ's had a resister inline the fuel pump power .
 

blu3fan

New member
Its probly not the pump. (
Check these three things.
1. Connections on the pump. every time you remove it and put it back in just makes the connection temp better - fix =Take a brass wheel to them.
2. the front engine grounds have failed at the dipstick. stopping voltage from getting to your fuel pump.
3. You have the ballast. Bypass that crap and destroy it... curse the person that invented it.
 

Anak

Stranger
NAXJA Member
How often is the fuel filter being replaced?

Has the tank been dropped to check for rust or other debris floating around in the tank?

I would be inclined to cut open the current fuel filter just to see what it tells me.

After that I would start to pursue the condition of the wiring.

For the wiring, one thing you could do is use the existing fuel pump power wire to run a relay and feed the pump with a better wire. I would upgrade the ground wire at the same time.
 

Spawn 93

NAXJA Member
NAXJA Member
X2 on the fuel tank possibly being full of trash. 3 fuel pumps into my 92 and I finally replaced the tank. There was enough rust in the old one that I basically built a replica tank when I got it out. Never another issue since.
 

studiousjames

New member
Thanks for the replies guys. Seriously. I think I am going to start with chucking the ballast resistor. it gets hot anyway. It looks like crumbly old crap.
Shop checked the tank a month ago.
@ tech1001 the pump runs normal on initial start up. after 5 minutes of operation it begins to whine like my ex. then its just loud as hell, until you really step on the gas then it squeals like a pig.
@Blu3fan I will def check those out. I have not gotten to look at the front connection, but with the amount of old oil I am cleaning off everything it would not surprise me. Also, how do you bypass the ballast? just plug the wires together?
@Spawn 93 The tank has been cleaned, twice. The filter might need changing again but my fuel pressure is still good at the rail.... anytime I have had a clogged filter it usually greatly inhibits the flow....
I just wanted to say thank you again for welcoming me and taking the time to help
 

blu3fan

New member
To fix the ballast
Cut the wires exposing fresh copper and solder both ends together.
Follow-up with heat shrink or electrical tape.
 

studiousjames

New member
ditched the ballast, checked the wiring, grounds are good, all wiring is fairly new.
replaced all the rubber lines, checked the tank and its not bad at all.
the old fuel filter looked to be nearly original. it was full of mud,
Installed shiny new pump and assembly, triple checked everything,
ran fantastic for about 5 minutes. New pump whines now, not as bad as the old.
I am wondering if possibly the Fuel Pressure regulator has plugged up as well?
Anyone ever heard of that?
 

Anak

Stranger
NAXJA Member
That fuel filter probably explains your past problems.

As to the new pump whining, at some level you should be able to hear it. What brand is the new pump?
 

ehall

NAXJA Member
NAXJA Member
The resistor was put in to cut the pump noise by reducing voltage. Removing the resistor means the pump is going to be louder.
 

stockerwithalocker

Got Shafted
NAXJA Member
My brother has a renix which had the same problem. His pumps would wine then die. After the 4th or 5th pump in less than a year we hardwired the pump to a switch. I’ll admit it was a ghetto fix, but in the ten years since hardwiring it he has not had an issue. If you find the issue please post what you find.
 

blu3fan

New member
My brother has a renix which had the same problem. His pumps would wine then die. After the 4th or 5th pump in less than a year we hardwired the pump to a switch. I’ll admit it was a ghetto fix, but in the ten years since hardwiring it he has not had an issue. If you find the issue please post what you find.
Like my post says... its the ground on the engine block dipstick side. or the pump wires....
 

studiousjames

New member
Update!
He's up and running right! 0 fuel pump noise, fires right up, and will smoke the tires if I am not careful.
Just wanted to say thank you again for all the help!
@Blu3fan ... it was the ground. but on mine its grounded up near the ebrake. Passes back through the cab and stuff. Took a minute to trace. The old pump was toast so I am glad it got that knocked out. Also I am going to be running an additional ground.
I found an ancient service bulletin in some of my dad's old shop manuals. Turns out the resistor actually does improve pump longevity
@Spawn93 My tank was actually surprisingly clean. I think the filter was factory if I am reading the part numbers right. I replaced the fuel pressure regulator as well. it was OE and probably worse off than the filter. Replacing it actually sorted out another vacuum issue I had been chasing.
So now I get to figure out where i knocked something loose. Because of course my little Pancho now has the issue of the gas gauge not working......i love my jeep
 

studiousjames

New member
@89Mock this is the diagram i used. its a lot easier to see where to look than in mine.
Its actually in the cab. The wiring passes up through the floor and then grounds out right up near the ebrake. I will personally be adding a direct to frame ground much nearer the fuel pump. Leave it to an engineer to think 4ft of ground wire with 3 connections would be better.....
Not sure yours will be exactly the same. Mine's a 2 door and there seem to be some slight differences in component location.
If yours doesn't match up to this then it should be located where the dipstick tube mounts. My buddy here has a 4 door same year as mine. His is on the tube, mines at the e brake mount. I would also look at your main ground too. Mine was just dirty enough to lose a bit of ground there.
 

89Mock

New member
Oh wow. Weird spot for a ground. I was thinking of replacing my pump because I think it's hard to start even though it starts every single time. It just cranks longer than I PERSONALLY think it should and it just gives me that "one of these times it won't start" feeling.
Mine is a 4 door. The diagram is a start. Maybe I'll just track it all down one night in the near future. I already did the ones on the engine dip stick.
 
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