Jeep running rough and stalling when driving

BeavisTJ

BeavisTJ

TJ Enthusiast
Supporting Member
Joined
Sep 27, 2018
Messages
315
Location
Queensland, Australia
Hey all so I was driving the other day going about 60kmh (37mph) and the Jeep started dipping in power and bucking/surging as I was travelling down the road. The engine cut out, I managed to pull over, clutch in, under no power except the momentum I already had and put the hazards on. I sat here on the side of the road for a little while trying to figure out what went wrong. The cluster gauges were bouncing all over the place when it happened so couldn't tell much from that.

Tried to drive a little further again and the same thing happened engine cut out after bucking a little while trying to stay alive. Engine died, clutch in and drifted to the side of the road. I popped the hood and checked the battery terminals as I felt it could be electrical but they were on tight and didn't have any play.

After a while I drove off again it seemed to sort itself out. Drove perfectly and didn't seem to miss a beat. Very occasionally there was a dip in power as if momentarily power was cut or something was off time.

There wasn't any codes that presented or even a check engine light. Tried to run diagnostics with some basic google apps but the Jeep wasn't having any of it. My OBDII wouldn't connect. I did check though the dash cluster and it said "no faults".

From what I've read this seems to be a somewhat common occurrence but never a definitive fix. So come hell or high water I will fix this and get my Jeep back! So stay tuned as I will update this thread when I fix it!

Another piece of information that could be misleading is I when at idle when I turned the air-con on or depressed the brake (IE put the engine under load) it spiked the symptoms.

This issue is completely intermittent, it will drive fine some days and then present this on others.

Research suggests that it could be:

- Faulty crankshaft position sensor (CPS)

- Faulty camshaft position sensor

- Faulty fuel pump

- Some other electrical gremlin

Apart from being a rather dangerous problem this is also my daily driver and don't want to get stuck out trying to get to work. But also don't want to just throw money at it.

So I beg can you please help me?
 
Here is a little clip from my drive to work this morning. If I'm quick enough on the clutch I can feather the throttle enough to keep the engine from stalling.

I went ahead and ordered a crankshaft position sensor that will hopefully arrive in a day or two.

View attachment 76058
 
Does the engine have the same problems after it is first started in the morning, before it has started to warm up?
 
Jerry Bransford said:
Does the engine have the same problems after it is first started in the morning, before it has started to warm up?
Click to expand...

I seemed to have a problem with the fuel pressure on a cold start. As sometimes it needs to be primed with the ignition a few times to get the pressure up (maybe a check valve) but it was live-able as it drove fine after.

So to answer your question there are some issues on starting but not when its running. Symptoms of stalling happen if anything at random or when engine is warm.
 
BeavisTJ said:
I seemed to have a problem with the fuel pressure on a cold start. As sometimes it needs to be primed with the ignition a few times to get the pressure up (maybe a check valve) but it was live-able as it drove fine after.

So to answer your question there are some issues on starting but not when its running. Symptoms of stalling happen if anything at random or when engine is warm.
Click to expand...
That sounds like the usual leaky check valve in the fuel pump. The check valve is there to keep the fuel up at the fuel rail for fast starts. It can leak and let the fuel drain back or partially back to the gas tank after the Jeep sits a while like overnight. Cycling the ignition switch on-off-on several times before turning it to Start gives the fuel pump more time to get the fuel back up to the fuel rail. The fix is to replace the fuel pump which contains the check valve.

Bosch is the way to go for a replacement fuel pump. What year TJ do you have? I was hopeful to find that info in your Profile but it's still empty with no information about your Jeep in it.
 
Jerry Bransford said:
That sounds like the usual leaky check valve in the fuel pump. The check valve is there to keep the fuel up at the fuel rail for fast starts. It can leak and let the fuel drain back or partially back to the gas tank after the Jeep sits a while like overnight. Cycling the ignition switch on-off-on several times before turning it to Start gives the fuel pump more time to get the fuel back up to the fuel rail. The fix is to replace the fuel pump which contains the check valve.

Bosch is the way to go for a replacement fuel pump. What year TJ do you have? I was hopeful to find that info in your Profile but it's still empty with no information about your Jeep in it.
Click to expand...

The start up problem does seem to sound like the check valve is failing causing fuel pressure to drop.

I've filled the information out just had another look not sure why it isn't showing up. Its a 2005 TJ, I'll be sticking to Bosch for the replacement.

However the main problem is the stalling when the Jeep is being driven. This is hopefully going to be fixed with the new crankshaft position sensor.
 
BeavisTJ said:
The start up problem does seem to sound like the check valve is failing causing fuel pressure to drop.

I've filled the information out just had another look not sure why it isn't showing up. Its a 2005 TJ, I'll be sticking to Bosch for the replacement.

However the main problem is the stalling when the Jeep is being driven. This is hopefully going to be fixed with the new crankshaft position sensor.
Click to expand...
I don't see any separate fuel pumps for the 2005-6 models, you may have to buy the entire assembly like is at https://www.amazon.com/dp/B000BZGCWY/?tag=wranglerorg-20

On 2004 and older you can replace the fuel pump by itself.
 
  • Like
Reactions: BeavisTJ
Jerry Bransford said:
I don't see any separate fuel pumps for the 2005-6 models, you may have to buy the entire assembly like is at https://www.amazon.com/dp/B000BZGCWY/?tag=wranglerorg-20

On 2004 and older you can replace the fuel pump by itself.
Click to expand...

Yeah that's right however it's not the main issue I'm facing at the moment.

I did pick up my order for a crankshaft position sensor and was hoping it would have included the cardboard spacer as discribed in the service manual. Does anyone know if it is necessary on the later models?

My crankshaft position sensor appears to be in a different position then older models.

76376


76380


76381
 
I’ve had that happen in my first car, a 1990 maxima. Sounded just like you described and completely random and sometimes took a while to restart. Ended up being bad gas. I put in the gas water treatment and ran premium for a few fill ups.
 
Camdenst said:
I’ve had that happen in my first car, a 1990 maxima. Sounded just like you described and completely random and sometimes took a while to restart. Ended up being bad gas. I put in the gas water treatment and ran premium for a few fill ups.
Click to expand...

Gosh wouldn't that be funny if it was. And I'd be happy if it's the case.
 
Ok so a little update crankshaft position sensor was replaced with a new one. Genuine mopar part.

76504


76505


76507


76508


Just so you can see where the crankshaft position sensor is.

Went for a short test drive and the symptoms returned. Driving along and engine stumbled, dropped in rpm as if it were about to stall. Giving it a little throttle and putting the clutch in saves it from stalling. But back to square one :(

Anyone have ideas?
 
So being the weekend no mechanics are open I decided to throw caution to the wind and hope that its just a poor quality fuel issue.

I added "fuel doctor" to the near empty tank and filled up with premium fuel. Hoping that might flush the system and fix things. Somehow I'm not overly hopeful, updates to follow.
 
I was experiencing the same problem once. I was getting a random buck when driving regardless of speed, before one day on my 20 mile commute home the jeep stalled out 4 times. Mine threw a code for the crankshaft sensor though. After that, all good.

I am still having the same long crank problem as you though. Not every time but almost every time. So I will be following this
 
An update on the progress. I've had the fuel pump replaced through warranty, the mechanics hooked up a fuel pressure gauge and sure enough the fuel pressure was dropping over night. This caused the hard starting/multiple cranks to get the fuel pressure back up.

The symptoms have definitely improved but still occur particularly when driving off in first on a hill or at slow speeds in second when turning a corner.

It will jump in revs like it wants to stall. Flash the engine warning light, but if I work the throttle more as I release the clutch it smooths out.

I had been reading perhaps it's the O2 sensors up stream intermittently failing. Not sure where else to go.
 
Update

I have taken it back to the mechanics that installed the fuel pump and they checked the fuel pressure again over night as well and scanned for any codes.

No luck, they told me the fuel pressure is fine and doesn't drop and couldn't get any codes.

I had order the NTK upstream o2 sensors, after research suggests it could be the sensors going bad and causing my issues.

They were very easy to replace and was cautiously optimistic that it would solve me problem.

Unfortunately after a short drive the issues continued. Jeep was hard to start, needing several attempts to run. And stalled a couple of times when starting off in first gear.

Any help with what I should start looking at would be fantastic!
 
Another update.

My research has started to lead me to believe it could be the PCM (ECU, cars computer). This is a worry as getting it fixed or replaced is a role of the dice. It could work great or show these symptoms again.

This morning I disconnected battery and then the plugs attached to the PCM. I did this for two reasons:

1. To clean the connectors with electrical spray
2. To reset the PCM

The reset is just buying time but figured it might give me more clues as to the problem.

Well I can say after "resetting" it has driven considerably better, throttle is crisp and smooth, idle is great and accelerating from a stop never gives the feeling it will stall.

After a long drive I had noticed the check engine. There wasn't any symptoms to suggest anything except again the hard starting.

Did the dash trick and got codes P0171 and P0174. Lean engine codes.

Not sure if this is to do with my main issue or if I've flushed something else out.
 
Update

Inbetween having mechanics look at the Jeep I had decided to rule out another sensor and replace the throttle position sensor. I had followed some basic testing procedures with a multimeter, the TPS signal wire had smooth voltage from what I could see although wide open throttle was low at 3.6 volts.

Went ahead and ordered a Mopar TPS for those interested the part number is 68404428AA

Installation was pretty straightforward, started her up and noticed a nice smooth throttle response and idle. The hard starting issue remained and requires a long crank and/or 2nd attempt to get going.

Unfortunately yet again despite a definite smoother throttle the stalling and bucking has continued...

The Jeep is booked into an auto-electrician Monday so I try to remain optimistic.
 
  • Like
Reactions: DaYooperTransplant
Top Bottom
Back