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lOlllOl 05-19-2013 01:36 PM

Help! Lurching/sputtering when accelerating
Hi guys. I really need some help with my YJ. I have a '95 YJ, 4cyl 5sp. I had my engine replaced back in November 2012 and up until this past month, it ran great. On my way home from work a few weeks ago, however, the Jeep did something strange and very frustrating. For the first 10-15 minutes of driving, the engine runs great. Then, upon accelerating in gears 1-3 from a dead stop, the RPM's will drop to zero, then spike and slowly return to normal. It will then do the same thing when I shift to the next gear. For example, here's how the issue progresses: From dead stop, accelerate in 1st. Once RPM's reach 2500, they drop to 0, then return to 2500 and stay there, even with the clutch in. Shift to second. RPM's return to what they should be, because I'm in gear. Once they reach 2500 upon accelerating, RPM's drop back to zero, just like in 1st gear. This happens for gears 1-3. Once in 4 or 5, no problems whatsoever. When the problem persists, I usually pull over and turn the engine off for 5-10 minutes; when I turn it back on, the engine runs great for 10-15 minutes, then the same problem happens. I can drive for hours on the highway, only if I can get to the highway within 10-15 minutes. Once I exit after driving for along time, the problem persists dramatically. The frustrating thing is, the Jeep will drive fine for 50 miles without a problem, like this past week, in stop-and-go traffic. The problem happens very randomly and at the most inconvenient times. I took it to three mechanics and none of them could replicate the problem. All sensors are new. Fuel filter is also new. My theory is that the sediment accumulation from the gasoline built up so much and is being pumped through the fuel system...but could be wrong. This is my everyday driver and I would really appreciate any feedback!!

jcbrindle 05-19-2013 01:49 PM

The RPM's drop to zero but it doesn't stall ? If you stay on it in 1-3 gears will it go past 2500 once the RPM's return?

AllMudd 05-19-2013 02:01 PM

Sounds like you fuel pump is going out. The pump is in the tank with the level sending unit. Replace the pump and while your in there you can clean out the sediment that may/may not be in there.

kik 05-19-2013 05:30 PM

Usually with those symptoms it's the Ignition Control Module or the in tank fuel pump with fuel injected engines. If there isn't enough pressure as the engine heats up, after approx. 10-15 minutes, the fuel atomizes too soon which causes a stumble situation as you derscibed. However, YJ's with faulty Ignition Control Modules have similar symptoms as spark is lost and picked up again.

lOlllOl 06-01-2013 10:13 PM

Hi guys...thanks for the replies. So after taking it to yet another mechanic, who once again could not replicate the problem, the Jeep drove flawlessly for ~75 miles, until the problem started again. Only this time, the RPM's would drop and stay at zero for a much longer time than before (1-2 seconds vs. .25-.5 seconds). I would keep giving it gas, at which point the RPM's would spike to where they should be during normal acceleration, then go back to zero for a few more seconds. The problem even started to happen in 4th gear, which never happened previously. At one point, the Jeep stalled right in the middle of an intersection and I could not start it back up. It would crank perfectly, but not fire. After letting it sit for a few minutes while several angry drivers passed by, I was able to fire it up and sputter to the shoulder. It then conked out on me again and would not fire (crank was still fine). I'd also like to mention that during the sputtering, the heck engine light would flicker, but not stay on. The only check engine codes I received were 12 and 55, which tell me no valuable information. Would a failing pump cause the light to flicker like that? I would think that a sensor (maybe cam position) would cause this, but the symptoms point more and more to a failing fuel pump...Then, after 15 minutes of staying off, it fired up, idled normally, and drove fine for about 3 minutes, until the problem returned. I would love to take it to a mechanic and have a professional diagnostic, but the darn thing runs great when they look at it! Is there any way to test the fuel pump to make sure it's the issue before I spend the time and money needed to replace it?

AllMudd 06-01-2013 10:21 PM

You can heck the fuel pressure with an external gauge, hook it into the shrader valve and you can see what it's running at. But question what was the weather like that day? Was it raining?

lOlllOl 06-01-2013 10:34 PM was bright and sunny. I did wash my car that day though. What does that have to do with it out of curiosity?

AllMudd 06-01-2013 10:41 PM

Was just curious if water was getting in either your plug wires or dist. cap shorting them out.

lOlllOl 06-01-2013 11:10 PM

I just popped the hood to see where the ICM is located. I found it behind the washer fluid container mounted to the firewall. Is this correct? Also, I noticed that the sticker on it had a date from November, 1994. Due for a replacement? Or should this part last long?

AllMudd 06-02-2013 12:41 AM

Never replaced mine and I have a 95 2.5, and I've never bothered to look for the ICM. Also have you tried swapping out your ign relay with the horn relay? My ign relay was weak and every bump I hit it would kill the engine for a couple mins he. Would run fin for 2-3 miles then off again. Maybe yours is getting hot and intermittently failing?

Jeeptrd 06-02-2013 06:40 AM

I was having a sputter problem with my 95 2.5 and after replacing a bunch of things the one that fixed my issue was the tps my mechanic buddy said they can develop a dead spot after a while. It also gave me a chance to really scrub the tb. Good luck!

lOlllOl 06-02-2013 10:09 AM

All sensors are new. I would also like to mention that on the day when I got stuck in the middle of the road, when the engine would crank for a while before firing, once it did fire, it would idle like crazy! Really low, then really high, then really low...all by itself. One would think someone was pressing the gas pedal. And then, it would just conk out again...maybe another sign of bad ICM?

lOlllOl 06-12-2013 11:31 AM

Hi guys...just wanted to give an update regarding what's happening with my Jeep. I finally got around to changing the fuel pump and bingo...problem solved. It feels like I'm driving a whole new engine too! Thanks for all the help.

crabman141 06-12-2013 11:41 AM

Awesome news and thank you for reporting the problem back.

lOlllOl 06-15-2013 07:01 PM

Hello again. I have some unfortunate news to report...the problem is back. I drove for about 300 miles since installing the new pump with no problems. Today, I filled up the fuel tank, got stuck in traffic, forcing me to shift a lot in 1st and 2nd gear, and the lurching returned. Any ideas on what's causing the issue now?? To rehash, the parts I can eliminate as the root cause include the fuel pump, fuel filter, clogged fuel lines, and all sensors.

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