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demon jeep

demon jeep

Banned
Location
American fork
I have a J-4000 with a 401 in it. yes it is a 401 it came out of a waggy.

The truck runs great when there is no load on it but when you put a trailer on it, it starts to get a miss fire and runs like poop
then after playing around with it for awhile it will be okay.
I just put new plugs, wires, cap, rotor, and new distributar. if there is anyone that knows what might be wrong please let me know, and if you come down and fix it (with my help) I will buy you lunch. Im at the end of ideas with this thing..

I did run it tonight with the TJ on the trailer and it ran okay could do for more power though.

Thank you
Demon jeep
 
MattL

MattL

Well-Known Member
Location
Erda
Have you checked the timing on it?
How about the fuel pressure, is the fuel pump good?
How is the routing of the plug wires? Could one of them be shorting out?Coil new?
 
demon jeep

demon jeep

Banned
Location
American fork
Originally posted by Shawn
You need to do a compression test.
Click to expand...

That is the only thing that I have not done I to scard to do that.
Becouse then I will want to rebiuld the engine and build it for ton of power, and that means more fuel, less life on tires, and having to stop someplace else on the way to moab. I have only 2 gas station I will stop at:D .
 
demon jeep

demon jeep

Banned
Location
American fork
It will tell you alot.
like
Valve spring no good and is not seeling all the time
low comretion( well dah) and fowling a plug
valves not seating also fowling plugs
bad head gasket

remeber it only misses some times then run great for awhile
and yes fuil pump ok and new fuel filter
 
Shawn

Shawn

Just Hanging Out
Location
Holly Day
Originally posted by demon jeep
It will tell you alot.
like
Valve spring no good and is not seeling all the time
low comretion( well dah) and fowling a plug
valves not seating also fowling plugs
bad head gasket

remeber it only misses some times then run great for awhile
and yes fuil pump ok and new fuel filter
Click to expand...

Yep,

Valves
 
B

bobdog

4x4 Addict!
Location
Sandy
You say it runs good sometimes and bad others. Do you mean it runs bad all the time under certain conditions, or does it run bad some of the time and fine some of the time under the same conditions. Does it seem to miss at any RPM or just at higher revs? Tell us more about the ignition set up, points or electonic?, seperate module? Have you replaced it? Timing initial and total? Do you have a timing light and compression tester? If you need to use mine get in touch with me.
 
BCGPER

BCGPER

Starting Another Thread
Location
Sunny Arizona
Ok, I'm going to asume you're running the factory Motorcraft ignition system. If so, have you replaced the ignition module? These are problematic, and do fail in diferent ways. Usually, the engine will just die, and if you're lucky will restart once the module cools. I did have one act up in much the way you've described. Changed the module, and the thing ran like a Chevy! If you're not running the Motorcraft set up........ Nevermind.
 
Shawn

Shawn

Just Hanging Out
Location
Holly Day
Nice!! I wish I could have made it.

I should have the Cruiser registered next week;)

Hows Delta looking these days?
 
demon jeep

demon jeep

Banned
Location
American fork
Originally posted by BCGPER
Ok, I'm going to asume you're running the factory Motorcraft ignition system. If so, have you replaced the ignition module? These are problematic, and do fail in diferent ways. Usually, the engine will just die, and if you're lucky will restart once the module cools. I did have one act up in much the way you've described. Changed the module, and the thing ran like a Chevy! If you're not running the Motorcraft set up........ Nevermind.
Click to expand...


It still runs that great old point system with vacume advance on it
the only motorcraft is the carb.


I towed with it to little moab and it did okay wish there was more power. It stumble once or twice but that was it
 
rustybronco

rustybronco

Flat Land Offroader
Location
Illinois
Ah hah!!! Why didn't you tell me it had a motorcraft carb on it? Better yet, why didn't I ask you. It's not your ignition. You're definately starving for fuel. My "new" old Ford truck w/460 has a motorcraft 4 barrel and had the same problem. Stumbled now and then. Turns out the fuel tank had some rust in it, and my grandpa had somebody work on it that was an idiot. They put a new fuel pump on it with a built in filter that hit the oil pan so you couldn't change it. And with two tanks, the selector valve had some crud in it. Also, the fuel line was running too close to the exhaust manifold off the pump. I'm assuming you've checked all of these things and now of them are your problem.....right? I ended up putting new fuel lines on it, and an electric pump. That eliminated the stumbling, now I'm just down on power cuz of that stupid motorcraft carb. I'm pretty sure the secondaries aren't opening. The power valve probably isn't working either. Work on that carb and call me in the morning!
 
demon jeep

demon jeep

Banned
Location
American fork
Its alive Well the post not the truck.

The damn thing is doing it agian. So I went and bought a commprestion tester and tested the cylenders all are at 120psi Yes I tested 4 or 5 times to make sure. So when you put it in gear it realy spudders and I have played with the carb a little but nothing will change. Im thinking of driving it off a cliff. DOH the thing wont make it there:mad: SO if any of you have any other Ideas please help or if you have a 350 or a 454 that you do not want and runs good for CHEEP let me know please
 
spencurai

spencurai

Purple Burglar Alarm
Location
WVC,UT
if you have some crap in the gas tank and a bad carb, it can make all those symptoms!! get that sucker rebuilt and cleaned out, I bet there is some funk in the bottom of those float bowls!!
 
rustybronco

rustybronco

Flat Land Offroader
Location
Illinois
Funk in the float bowls for sure! Or funk in the lines. Or funk in the tank. Or funk in the pump. Or funk in the filter. Dude, you've got funk! And why do you think it's overfueling? What do your plugs look like? The best carb tuners study the plugs. If it's overfueling, everyone will be black, not just a few. If you've got at least 2 brown ones, it's not overfueling.
 
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