Can't Get Renix To Fire

[Eagle]

Maybe his injectors are not recieving the signal to cycle open/close?

 

That's very possible, the the way to test that is a noid light. But the CPS controls both the ignition and the injection, so if there's a signal to fire the spark plugs, the problem isn't the CPS.

[diablo8511]

When I put gas in the throttle body it starts up and runs. It will continue to run, I can turn it off and will start back up. After sitting overnight or a certain amount of time it will not start up without putting gas in the throttle body.

[Eagle]

After it has sat overnight, when you turn the key to the RUN position (not START), does the fuel pump run for a few seconds and then shut off?

[diablo8511]

Yes

[MancheKid86]

May sound weird,

Maybe vapour lock from a leak in your fuel line/TB?

[88MJNC]

try spraying starter fluid into air filter housing through rubber tube off left hand side. Just to get it running.

[88elimnator]

ballast resistor the ceramic block on the driver side inner fender

[foreman1063]

If you open the throttle body butterfly to WOT by hand will it start? If so, check the TB IAC for crud. Clean IAC and TB and try to start.

My sons XJ had the same symptoms and that's how I fixed it. Had fuel, good spark but no start. TB and especially IAC were filthy and caked with crap, cleaned with carb cleaner and started right up and ran like a champ.

Good luck.

[cz777]

All 6 of them clogged?

RUST! yes with all this bad gas today maybe ? what is your rail fuel pressure ?? got a noid light LED light to see if injectors are getting fire from the brain and seeing if wiring is good too .....

[88mjgilley]

When I put gas in the throttle body it starts up and runs. It will continue to run, I can turn it off and will start back up. After sitting overnight or a certain amount of time it will not start up without putting gas in the throttle body.

 

so when you put gas into the intake it will start and you can drive it just fine or it only runs when your feeding it gas your self into the intake

[88mjgilley]

if that is the case try jumping the starter with the key on it sounds to me like your ingintion switch is bad so when you are cranking it over by the key it is killing the signal to the injectors causing them not to cycle i use to have this issue but backwards when i would turn the key to the start pos it would run but as soon as i would let off the key it would die

[88MJNC]

Mine has been doing the same thing yours has been doing I get by with carrying a can of starter fluid with me if it cranks I'm good if it doesn't I spray alittle starter fluid. My truck has puzzled all the certified and non certified repairmen in eastern nc. I swing into repair shops to give them a challege and still no one can figure it out then I break out the starter fluid and it fires right up. The newest repair man did some digging through some wire diagrams and old tech articles. It sounds like it is the closest reason why it's not firing. On the older MJ's it needs 12 volts to fire and run fuel pump in the start ignition position but when the key is turned to the start position it only gives 6 volts which doesn't givecenough juice to run. Then if you turn it back to run position or acc mode it has 12 volts. So asked him to study it alittle more.

[cruiser54]

Mine has been doing the same thing yours has been doing I get by with carrying a can of starter fluid with me if it cranks I'm good if it doesn't I spray alittle starter fluid. My truck has puzzled all the certified and non certified repairmen in eastern nc. I swing into repair shops to give them a challege and still no one can figure it out then I break out the starter fluid and it fires right up. The newest repair man did some digging through some wire diagrams and old tech articles. It sounds like it is the closest reason why it's not firing. On the older MJ's it needs 12 volts to fire and run fuel pump in the start ignition position but when the key is turned to the start position it only gives 6 volts which doesn't givecenough juice to run. Then if you turn it back to run position or acc mode it has 12 volts. So asked him to study it alittle more.

 

That's the way it's been since 88. Except your voltages are incorrect. Battery voltage on ALL MJs while cranking. Voltage to the pump reduced to 10 volts on running.

87s had a dealer installed kit to REDUCE the voltage to the pump by installing a retro-fit kit to do just that. 88 and later came wired that way. If you're suspicious of the reduced voltage, bypass the fuel pump ballast resistor with a jumper and see what happens.

[88MJNC]

Thanks cruise just going by what i was told on voltage.

[cruiser54]

Thanks cruise just going by what i was told on voltage.

 

Don't believe those people any more.

[88MJNC]

Will do cruise. Today went to napa and upgraded my grounds like your DIY article, also replaced the fuel regulator. Will see how this goes.