Wtf?!?

[Buck hour]

This is something new for me. Yesterday I was sitting in the drive thru at the bank. Engine was idling great. Then with out warning the engine started to stumble slightly. By the time I got out of the parking lot the engine wouldn't run unless I hold the gas peddle down. Now it sounds like a helicopter when you do get the engine running. Touch the gas and the whole jeep shimmies.

I already have :
A new carb
New fuel filter
Relatively new wires plugs and coil
New battery

Please help or I shoot the jeep!

 

[jps4jeep]

electric or mechanical fuel pump?

I am really leaning towards the new carb, how new? was it tunes when installed, how often has it been tuned?

the 10-15% ethanol in modern fuel will wreak havoc on a carb in a short amount of time, especially if it is outfitted with paper gaskets. I installed an edelbrock 1406 on my plymouth and it was fouled with in 500 miles (in the north east we run 15% ethanol.) Depending on your carb, the manufacturer might offer a ethanol compatabile re-build kit.

 

[jps4jeep]

To add and this is just a note for anyone, with a carb, if a E15 compatable kit is not available, over jetting one orifice size and bumping the timing ~1 degree usually will get a lot more longevity out of the carb with the e15 fuel.

 

[Buck hour]

electric or mechanical fuel pump?

I am really leaning towards the new carb, how new? was it tunes when installed, how often has it been tuned?

the 10-15% ethanol in modern fuel will wreak havoc on a carb in a short amount of time, especially if it is outfitted with paper gaskets. I installed an edelbrock 1406 on my plymouth and it was fouled with in 500 miles (in the north east we run 15% ethanol.) Depending on your carb, the manufacturer might offer a ethanol compatabile re-build kit.

The carb is a weber 38/38 dges outlaw. Its been on the jeep since January 2011. I'm in Chicago and I think we use 10%

I can keep it running if I keep it over 1500 rpm. But even then it's pretty rough and shakes the jeep.

 

[TerryMason]

Spark plug wire off?

On my CJ there was an exhaust pipe inside the engine bay that would slip off every couple thousand miles and would cause a huge lose of power, change in engine sound, etc. Probably not much help, but take a look there.

 

[Saddle Tramp]

Its the Weber. This is from the been-there-done-that department.

 

[superj]

I would check your wires also.

Start with the easy stuff first

 

[Buck hour]

To be more accurate it sounds like rapid misfire. Like someone is shooting a machine gun.

 

[Buck hour]

I would check your wires also.

Start with the easy stuff first

I'm going to. They are cheap 7mm wires. I've just never seen a wire break down that fast

 

[superj]

i have had wires bad out of hte box is why i say start simple.

 

[Buck hour]

i have had wires bad out of hte box is why i say start simple.

I just replaced the stock wires with 8mm,today. No change in symptoms

 

[superj]

ok, so it sounds like a machine gun when running? pull your cap and check your rotor button and tip and check the contacts in the cap. also, check your plugs to see if they are fouled. if they are, start looking at tuning that weber back a little if they are reading rich

 

[Buck hour]

ok, so it sounds like a machine gun when running? pull your cap and check your rotor button and tip and check the contacts in the cap. also, check your plugs to see if they are fouled. if they are, start looking at tuning that weber back a little if they are reading rich

Yeah while the engine is idling. It's almost the same sound when pull a wire off the spark plug while the engine is running. But a little more muffled and much quicker in succession.

Checked the cap and spark plugs. Plugs show signs of use but are in good shape overall.

 

[54cj3b]

did you check to see if it jumped time

 

[Buck hour]

did you check to see if it jumped time

No I haven't. But I don't beat on her and the noise started while it was idling. I'm leaning more towards a distributor or the "bid" ignition box.

 

[Buck hour]

Is there a way for me to post a sound clip on here?

 

[superj]

if you have photobucket, it will let you post sound as a video clip.

is it backfiring through the carb at all? i had a 79 chevy step side that was backfiring through the carb because a pushrod bent and stuck the valve in the open position. maybe you have a valve that is not closing all the way?

 

[Buck hour]

if you have photobucket, it will let you post sound as a video clip.

is it backfiring through the carb at all? i had a 79 chevy step side that was backfiring through the carb because a pushrod bent and stuck the valve in the open position. maybe you have a valve that is not closing all the way?

You can hear it thru the manifolds. But no not they the carb. It happens to frequently to be only one valve. I've sent a sound clip to terri. He said he would post it here.

 

[Buck hour]

Here's a brief sound clip

http://www.jeepz.com/videos/buckhour.mp3

 

[flatie46]

You could start pulling plugs, you'll be able to tell which one (or ones) are not firing. Then that'll let you know if it is a plug wire you can track it down. If it's a fuel problem they'll all look about the same.