• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Renix XJ Fuel pump question

T

thanasi85

NAXJA Forum User
Location
Sacramento, CA
Having issues with my rig not starting recently. Tracked it down to an issue with the fuel pump not priming all the time, sometimes I will hear it prime when I turn the key to the on position and it will fire up and other times I will not hear it and it just cranks and cranks. I already cleaned the fuel pump connection, replaced fuel pump relay, replaced fuel pump ballast resistor and tightened up the connectors to it. My next thought is maybe the ignition switch may be the issue but not sure if I would be having issue with my accessories not working also if that was the case. Any help would be great.. thanks
 
Sounds like a fuel pump problem i just encountered in my renix jeep. A new fuel pump should solve it. Better take care of it before you get stranded
 
To add to this, as I understand it, the ballast resistor is responsible for reducing the current to the fuel pump during initial startup simply to reduce/mask the noise that the pump generates at full speed. As per the previous poster, your symptoms could be a sign that your fuel pump is getting old and the lower current isn't enough to spin it up anymore.
 
tjmotter said:
To add to this, as I understand it, the ballast resistor is responsible for reducing the current to the fuel pump during initial startup simply to reduce/mask the noise that the pump generates at full speed. As per the previous poster, your symptoms could be a sign that your fuel pump is getting old and the lower current isn't enough to spin it up anymore.
Click to expand...

It gives LOTS of power to the fuel pump upon starting, and then reduces the voltage once running to reduce fuel pump noise.

OP, how's the ground side of the fuel pump connector.
 
cruiser54 said:
It gives LOTS of power to the fuel pump upon starting, and then reduces the voltage once running to reduce fuel pump noise.

OP, how's the ground side of the fuel pump connector.
Click to expand...

and the wires inside the tank from the sending unit to the pump itself.

although if you're going that far you can just replace the pump.
 
Thanks for the input. I have a spare pump I can toss in but first I'd like to know more about testing the ground to the pump. How do I test the ground for the pump? I have a meter, do I back probe the ground wire in the three prong connection for the pump and have someone turn the key to the on position or do I disconnect the connection and just touch the black ground wire in the connection? What readings am I looking for. I can tear apart a XJ and but it back together in my sleep but when it comes to electrical issues and testing wires Im still learning the ropes.
 
So what do you do to get it started when it " just cranks and cranks"?

Sounds to me like a loose CPS connection.

Next time it does it try unplugging and plugging the CPS in.
 
cruiser54 said:
Set meter to ohms. Back probe the connector on the ground wire. Touch the other lead to a known good ground. should have zero ohms.
Click to expand...

So tested the fuel pump ground wire with the ignition off and got a reading of around 1.5 ohms. With the ignition on it gave a reading of almost 20 ohms. What should be my next step?
 
Check the fuel pump ground and clean to bare metal.
XJ%20Body%20Ground_zpsiq4kdo5d.jpg
 
my2monkeys said:
So what do you do to get it started when it " just cranks and cranks"?

Sounds to me like a loose CPS connection.
Next time it does it try unplugging and plugging the CPS in.
Click to expand...

Your right on the money with the symptoms being indicative of a bad CPS but in this case I know is not CPS related and has to do with the fuel pump.

cruiser54 said:
Check the fuel pump ground and clean to bare metal.
XJ%20Body%20Ground_zpsiq4kdo5d.jpg
Click to expand...

So I never knew that wire back there was the fuel pump ground. It looked pretty hacked up so I cleaned the body surface, cut the end of the wire and exposed fresh wired and crimped on a circle connector at the end then re attached it. I came out this morning at it fired fight up. Hope this did the trick but I will give it a few days and see if the issue return or not then post back

IMG_1397_zpsamhcsi29.jpg
 
This is good to know. I had no clue that there was a ground back there. I'll be pulling my panel off next day off to inspect mine. I was having a similar issue with mine, I put a pressure gauge on the rail and found it was priming to 1-2 psi and would run ( rough ) at about 10 psi. Unplug the map sensor and it would clean up enough to idle. Bad pump right, pulled it and found the hose coming from the pump to the bulk head had come off so I was priming back into the tank and pumping just enough to run into the line and the rest back into the tank. Repaired it. Night and day difference but I still don't always hear a prime and it takes a bit to start. That ground may be the ticket.
 
You must log in or register to reply here.

Similar threads

Ecomike
87 Renix XJ No fuel, No brake lights, cranks fine
2
Replies
27
Views
862
Anak
Anak
N
New Engine is Hard to Start
Replies
0
Views
34
NGThomas
N
Z
RENIX fuel delivery questions
Replies
4
Views
336
Ecomike
Ecomike
S
1998 XJ no start - No fuel pressure
Replies
11
Views
2K
sjx40250
S
R
No spark
Replies
1
Views
1K
Ecomike
Ecomike
Back
Top