TJ loses power on highway

[pompeytir]

I have my wife's 2004 Jeep Sahara. The following has happened 3 different times...

This last week, the Jeep dies is going fine on the highway. I hear a stumbling and the engine no longer responds to the accelerator. It goes from 60mph to 0 mph but doesn't lose electrical power. (it also did this deccelearting on an exit ramp)

I pull it over, pull the key out and start it and it starts but is stumbling and the accelerator doesn't respond, I pull the key out again.

However, I wait 5 minutes try it again and the car starts perfectly normal. I drive it 20 miles home, up and down hills with no problems.

Not sure what it could be but I was able to replicate the problem 3 different times in a week. No check engine lights, no engine temp problems, no slipping of the transmission. I have replaced the fuel assembly about a month ago (Delphi as Bosch is unavailable).

Would love some help, thank you!

 

[JEEPCJTJ]

How did you replicate the problem?

 

[pompeytir]

I just drove it again for 2 days straight to work and on the 2nd day (when I thought it was a fluke) it happened again.. (so probably a 100 miles before it happened again). And it just happend this afternoon (with temps in the 80s).

 

[Jerry Bransford]

Sometimes there will be a "Pending DTC" (diagnostic trouble code) that won't show up or cause a CEL. Try plugging an inexpensive code reader like from Harbor Freight (what I ended up with) and see if it shows any pending codes.

 

[Jodh]

Mine did something similar and it was main wire harness on the firewall. The locking tab had broken and it pulled apart just enough to break the connection. I zip tied it together and no more problems. May not be your problem but its a place to look.

 

[pompeytir]

No code, I hooked my scanner up and it was clear.
I was thinking was the fuel pump going bad (it takes 2 turns to get it to start lately) or maybe the cat was clogged? Would it be one of those? Do the symptoms make sense?
I will check for wiring possibly being fried.

 

[Jerry Bransford]

That sounds more like a bad fuel pump and not the catalytic converter. My cat completely clogged years ago and dropped my speed from 65 to 3-4 mph in about a quarter mile. The engine ran fine it just couldn't rev up. A weak/bad fuel pump is not likely to cause a CEL, and never in my experience.

 

[Jeffreybomb]

Have you tried not calling it a “car”?

(ducks)

 

[pompeytir]

Could the fuel pump intermittently fail? Wouldn't it be more consistent?

 

[JDS123]

When my fuel pump failed for the first time, my Jeep would die somewhat randomly when driving and would fire up just fine after waiting a few minutes. Next time it dies, immediately cycle the key and see if you can hear the fuel pump fire up.

 

[Hopper]

My Jeep just did that a week after a Napa fuel pump went in exept it didnt start back up until the next day drives fine know. Mechanic thinks it's over heating. I tried to tell him what yall told me about the Napa pumps. He ordered a Delphi and replaced the grounding strap? hope it helps. I wish the bosch were available. I PM a couple of guys on here that put the Delphi in a couple yrs ago and they said it's still running good.

 

[Jerry Bransford]

My Jeep just did that a week after a Napa fuel pump went in exept it didnt start back up until the next day drives fine know. Mechanic thinks it's over heating.

That's a clueless mechanic who would think that. Most modern and all fuel injected Wrangler fuel pumps are cooled by the gasoline as it passes through the pump. As soon as the TJ's engine dies for any reason the PCM immediately shuts the fuel pump off.

 

[pompeytir]

Thank you, I changed the crankshaft sensor tonight (saw on another post that someone said it was the problem). I will post an update if that does/doesn't work for anyone else that might have this problem. I have no problem with swapping out the fuel pump, just hard to wrap my head around it going bad out of the box

 

[Hopper]

That's a clueless mechanic who would think that. Most modern and all fuel injected Wrangler fuel pumps are cooled by the gasoline as it passes through the pump. As soon as the TJ's engine dies for any reason the PCM immediately shuts the fuel pump off.

Thanks Jerry this guy is a little hard to understand Taiwan. He has been good with keeping my service trucks on the road and let's me use his lift and tools for fixing my frame and soon replacing cooling system. Although a great guy I can tell he doesn't know alot about TJs especially when he said I should lift it with rough country I may of misunderstood him with the "over heating" or he may just be an idiot like me.
Is it possible that the pump just went bad or what else should I be looking at? Oh shit am I high jacking a thread?

 

[Hopper]

Thank you, I changed the crankshaft sensor tonight (saw on another post that someone said it was the problem). I will post an update if that does/doesn't work for anyone else that might have this problem. I have no problem with swapping out the fuel pump, just hard to wrap my head around it going bad out of the box

Let us know how that works out very interested. What brand did you go with on the crankshaft position sensor?

 

[pompeytir]

I used a mopar crankshaft sensor from RockAuto.

It is not the crankshaft position sensor. The Jeep lost power twice today (after driving to work fine yesterday), but weirdly, I just pulled over to the side of the road and without turning off the motor, the car regained it's power and I was able to drive to work (and then to home the 2nd time). Swapping out the fuel pump as soon as the new one arrives. Hope that works.

 

[freedom_in_4low]

sounds like a fuel supply issue to me, for sure. May have dropped some junk in the tank when the last one got changed and clogged stuff up.

It's acting a lot like my 2000 Silverado did back in February...only it wouldn't run right again afterward, just idled like crap and died if I put any load on it whatsoever.

 

[pompeytir]

Yeah, I don't want to believe it's the fuel pump but I'm swapping it out anyway. Crossing my fingers it works

 

[My CJ and Her TJ]

Your computer died I believe...we had the same thing happen to the wife's jeep. I got my new ECM from here: www.wranglerfix.com He is very helpful and will actually answer the phone himself. Good luck!

 

[pompeytir]

and...3 weeks later. After replacing Crankshaft sensor, Camshaft sensor...

it is the 90 day old DELPHI Fuel Pump Assembly that was bad. I actually took it to a family friend's shop and they were flummoxed about it...it had fuel pressure but was also pumping excess air at the injectors.

Fuel Pump replaced on Tuesday and no issues since.