• 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.

Unique Renix no start issue (yes... I've searched!)

E

eroc37

NAXJA Forum User
Location
Atlanta, Georgia
89 stroker motor has been running flawlessly for months. I shut it down normally, it would not restart a short while later or ever again...

Turn the key it will crank, fire, and begin to run but let go of the key... nothing. I thought I flooded it but every sign of life vanishes when the key returns to the run position.

I know it's getting fuel, I have already removed the fuel pump ballast, the IAC is new, and I've tested the CPS both static and for AC voltage while cranking. it all seems fine.

Is there something electrical that could work in "start" but not in "run"?

Anyone have an idea?
 
cruiser54 said:
Bad ignition switch most likely.

The Run position is FUBAR.
Click to expand...

Most likely what Cruiser54 said, although, the fuel pump is powered in the START position by the starter relay, then idle through just short of WOT by the fuel pump relay. I would check the ballast resistor or the fuel pump relay.
 
Something electrical might include the ignition switch itself.

Ballast resistor. The white thing...check it out.



The wires may be disconnected, the resistor itself may me broken
You can connect the 2 wires together to take the resistor out of the loop. The fuel pump might buzz a bit more but if that's the problem...you'll know right away by jumping it. Replacement cost - $11.75 Ba-da-bing!

Ask yourself "what changes when I let go of the key ?? " Therein lies the answer.
 
Last edited:
Ive already '86'd the ballast resistor after it disintegrated and research here told me it wasn't needed.

Since my DD is a cummins, I routinely turn the key on and let the fuel pump run until it stops then turn key to start. I know the fuel pump comes on at initial key to 'run' position. Could the ignition switch be failing only at release from 'start' position back to run?

I guess the multi meter will tell me in the morning!
 
Here is the "fun" part of the XJ fuel pump:

Turn key ON, ASD/Latch Relay energizes the fuel pump for 3-5 seconds, and then cuts the power when no signal from the crank sensor is recognized. Turn key to START, the starter relay provides power to the fuel pump bypassing the ballast resistor. Engine starts, return key to ON, the fuel pump is powered by the fuel pump relay through the ballast resistor BUT at WOT the fuel pump is powered by the o2 heater relay.

There you go--the "fuel" story of the XJ's fuel pump power supply.
 
OK, I...
1. tested the fuel pump relay - it's fine.
2. made sure the fusible link to the fuel pump relay + has power... it does
3. replaced the butt connector where the ballast resistor used to be. it looked fine but I changed it anyway just to be sure.

Still no start. so I replaced the ignition switch. now turn the key, no crank! I have dual fully charged optimas, I know I have the juice... the volt meter (aftermarket) drops to zero and no crank??? I have redone all the cables and grounds and it has been running flawlessly for months.

it did actually crank a few times and the engine started once, ran poorly and stalled. It does want to start while cranking (when it will crank!) when i let go of the key... nothing.

1. Why won't it crank now? I am changing back to the original ignition switch.
2. Why won't it run? Could it be the IAC?? I can't find how to test it and hate to be a parts swapper.
 
I installed properly adjusted the new switch.

It turns over like a champ and quickly tries to start. the first time it caught and went into high idle like a good Renix should then the idle gradually slowed to stall (with some backfiring)

Upon restart it would only catch and not run.

I've checked for vacuum leaks, I know the fuel pump is running because I can hear it (no ballast resistor) and it smells flooded after repeated attempts.

Could it be the IAC? I replaced the current one about 2 years ago and the jeep has mostly sat until this summer.

Is there anything else that could change the conditions between 'start' and 'run'?
 
Last edited:
it is an aftermarket pump. I pulled the fuel line before the filter and there's flow with the key on. I've never replaced the filter but I have replaced the pump. I am going to change the filter tomorrow just because and retest.

Is there a problem with aftermarket pumps I should know about?

Wow... I just learned a universal truth...

"just because the fuel pump makes noise does not mean you have fuel at the injectors"
 
It did but I'm not sure I trust it. I picked up a NAPA gold fuel filter I will install in a little while and recheck fuel pressure.

Stay tuned viewers!
 
Changed fuel filter, yes, it's on the right way... still no pressure at the rail.

anything else I should check before installing a new fuel pump? Searching led me to the Bosch pump as the best?
 
the pump makes noise like it's operating properly. this is why I didn't check fuel flow in the first place.

A failed pump would make sense given the fact I parked the jeep and it would not start again.
 
The rubber fuel lines inside the tank will pop off or deteriorate--the pump will run, the pump will pump, but the fuel doesn't go to the rail.

For a stock early XJ the Bosch 69302, cheap from rockauto.com $64.79.
 
joe_peters said:
The rubber fuel lines inside the tank will pop off or deteriorate--the pump will run, the pump will pump, but the fuel doesn't go to the rail.
Click to expand...

That's what happened with me. The rubber hose between the fuel pump and the outlet for the tank had slipped back so that it was just making contact with the inlet. It would sit in place and push gas out from the fuel filter ok (just like you are seeing) but as soon as it tried to build pressure, the hose would flex back a little and release most of the gas back into the tank. It was actually a pretty simple fix, I kept the old pump (Bosch) and just cut a bigger piece of rubber to connect the two.
 
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
869
Anak
Anak
S
No Start No Bus
Replies
16
Views
3K
Rob Mayercik
R
U
Electrical issue
Replies
6
Views
2K
UltimateG
U
W
1999 XJ - No start - PCM?
Replies
1
Views
2K
Tim_MN
Tim_MN
N
New Engine is Hard to Start
Replies
0
Views
34
NGThomas
N
Back
Top