No power??????

Webbinator

Webbinator

Well-Known Member
Joined
Mar 20, 2005
Location
York, SC
There's been a problem on my '78 CJ7 258 that I've been trying to work out for some time now. The thing starts up and idles great. When I take it for a drive, I can go roughly 5 miles and it will start to lay down on me. It really gets bad if I'm going up a slight grade or just simply get on the gas. The power just goes and it sometimes will pop and buck. I've already tried a new coil, cap, and rotor. I'm running a full MSD ignition system also. I could probably spend a small fortune trying things to fix this. I'm borrowing another distributor this weekend to see what might happen. Just trying to eliminate anything that might be causing the problem. Anybody here got any suggestions on what could be causing this and what I could do to fix it. This jeep used to be really reliable until I quit using it for a DD. I guess things start to go when they just sit most of the time.
 
First, you are missing a couple of cylinders...(shoulda had a V-8 :D ) thats why you are down on power...

When it starts to run bad, put your hand near the MSD, check to see if it's getting hot. Given that it takes some time to warm up before it gets bad, I'd look there first.
 
Open your fuel cap and see if it magically starts to run right again... ;)
 
my 81 does almost exactly the same thing. runs great at idle and around town, but on the highway at higher rpms it starts to bog down. i think i'm with rich that i've got some type of fuel delivery problem, maybe it's not vented correctly or something. i'm gonna try the gas cap thing and see if that helps, i hadn't thought about that....
 
And also, I hope it's not the freakin' MSD box. I've been wondering if that might not be the problem. Them things aren't cheap to replace. But then I guess being fixed is a better alternative to what I have now.
 
Webbinator said:
I didn't realize the fuel cap thingy mattered on the older jeeps.
Click to expand...

If you're not getting proper venting, the tank will get under a vacuum, and starve the engine...
 
I can't remember who it was but on the previous board someone had the same exact problem. You may be able to have the Admin let you look?
 
My Willys does the same thing when the fuel filter starts getting clogged.Have you tried anything on the fuel system yet?
 
A friend of mine has an early 80's Chevy 3/4 ton work truck with dual tanks, and it would cut off at stop lights. Bought a new fuel cap and that fixed it. Apparently the fuel cap was not venting properly.
 
Yep, I tried a new fuel filter when the problem first started. Didn't help any at all. Funny thing is that this just came on out of the blue a while back. I'm getting ready to take the fuel cap off and take it for a drive. If the fuel cap does make a difference, what do you do to fix it with the cap on. I was thinking maybe drill a very small hole somewhere in the cap to help it vent the tank.
 
Oh well, gas cap thing made no difference. I took the cap completely off and went for a drive. The problem is still there. Also when it stated doing the "no power" thing, I pulled over, raised the hood and put my hand on the MSD box. It wasn't anywhere near what I would call hot or even really warm. I can tell already that this is gonna be a fun one to figure out.
 
ok,check out any rubber lines along the fuel route from the tank to the carb.Sometimes a rubber line will collapse internally and cause a major restriction.Also,when it starts,when you pull over and give it a minute to idle,does it act up right away when you start off again or can you go distance before it starts back up?For some reason I'm thinking more inlines of a fuel problem than electrical.
 
taking the gas cap off didn't do anything for me either.....mine only does it on the highway and only under load...trying to maintain speed up an incline. the engine slowly bogs down and then stutters. i've tried different timing settings as well as float settings. i think the carb is pretty well set up, it starts, idles, and runs around town great. it's not like i can't drive on the highway, it's just hard to maintain above say 60 on any sort of incline. straight and level i can maintain close to 70.

webbinator, sorry for horning in, not trying to hijack ur thread, just that our problems are really similar.
 
No problem at all there tsjeepcj. Heck, we're all in this together. I actually may have solved my problem yesterday. Still got my fingers crossed that it holds out. I changed out my distributor of all things. I had noticed when I did the throttle in my driveway that I didn't see the vacuum advance moving hardly at all. I got hold of a good used distributor and swapped it in. After getting the timing all set again I took it for a good 10 mile "round the block" drive. It never acted up even once. Oh, and now when I do the throttle, I can see the advance moving quit a bit. I'm pretty sure that the other distributor was the original one, so maybe it was just worn out. Like I said, still got my fingers crossed.
 
hopefully that worked for you. since i've gotten my jeep last summer i put in a new distributor, ignition module, rebuilt carb, and gone to tfi. i'm not gonna put too much effort into solving this, i'm swapping in another 258 w/fuel injection sometime this summer. but, i'd love to know why it does this.

anyway, hopefully your fix will work. cya

tim
 
tsjeepcj said:
i'm swapping in another 258 w/fuel injection sometime this summer.

tim
Click to expand...
258 with FI...rare breed indeed. All the top end power of the 4.0 with the gunt of the 4.2.
 
Guess what? Now I have the same problem, got the new starter and everytrhing done, fluids and all, so i take her for a drive tonight, does perfect until about 300 feet, i stop talk to my friend and then continue to drive another 50 feet, and all of a sudden the RPMs drop and it cuts itself off, its like its not getting any gas at all and itll bog itself out. Ill be in the middle of driving it, and giving it gas and itll just start catching and losing power completly and shut itself off, Ill restart it and itll start back up and a few min later do the same thing again. It does it even when the clutch is disengaged and im reving it to try to keep it on as soon as I let off itll bog itself back down
very confused, this is the first time its been driven since our swimming accident :confused: 86 chero 2.8 V6 also sorry to jump in, but it seems everyone is having around the same problem
 
Also it never started doing it till I drove it yesterday, it idled great three days ago
Ryan
 
start a new thread please....
 
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