beyond baffled on this one

[Mudrat]

OK,
I’m beyond frigg’n baffled on this one. :-|

1987 YJ, 258 bored +30, balanced, Webber 38 on spacer plate, 4700 miles on the engine, transmission and T-case (w/the 231 SYE). It has the Nutter bypass and TFI with new coil and wires (there is no computer module or smog), stock intake/exhaust manifolds. All the plugs are a beautiful tan and gapped at .45 for the TFI.

We’ve put over 4000 miles on this motor with no problems, then my daughter started having problems a couple weeks ago while ‘just driving’ (she’s not a speed demon either) and said it “just quits” on her at various speeds. I put almost 400 miles on it to/from work with out a problem – until today. At 30mph, it just stopped running. At 45, it just quit and at 65 on the freeway, well . . . I coasted to the side of the road. All within 45 minutes!!! Each time it takes 1-2 minutes before it’ll crank over again. Turned around and came home. Each time the oil pressure was 30-50 PSI.

I’ve checked:
- All electrical connections and plug wires
- All fuel system hoses (new on rebuild)
- fuel pressure regulator is set at 5PSI for the Webber.
- Vacuum lines (new on the rebuild) are in place
- Starting it up a little while ago it back fired through the carb while cranking (not sure the state of the power valve/accelerator pump now). this indicates timing, but...
- Timing is spot on – though the timing light does ‘shift’ 5-6* like the spark is early/late occasionally (random intervals 5-10 seconds apart) and I wrote that off to interference with #2 wire, but . . . I'm puzzled 111!!!

This happens anywhere from 30-70 degrees ambient temp. Engine is never over the T-stat at 190-195*, it’s still winter here :roll:
Vapor lock is what I’m thinking, though I can’t see how since the fuel pump, lines and filter are cool to the touch after running it around for 20-30 minutes or so – well within the time that it quits. 111!!!

I’m about to go reroute the fuel line from its stock position well away from the valve cover and heater hoses just in case. And I’m thinking about popping the valve cover off and checking torque on the lifters (hydraulic) just in case, but there is no valve chatter that I can hear with the stethoscope.

I’m open to suggestions and any straws I can grab at. Erin needs this for college, and the other 2 running trucks are needed for my wife and I to get to work, The man-child is SOL until we can get his Blazer rebuilt – or I get the Waggy running. :oops:

Went looking for a replacement carb for the Webber - an MC2100 and NOBODY in the 6 parts stores near me can get one this week (and the cheapest is $235!!)!!! :shock: NAPA doesn't even lit it 111!!!

[tufcj]

Fuel or ignition.

Any sort of ballast resistor or fusible link in the ignition that could go open when hot? I have a unilite module that will run for 1 to 500 miles, then shut down. Turn the key off, it will always restart immediately. I keep it for a spare.

Pop the lid off the carb. Is the float sticking and starving it for fuel?

Just a couple of thoughts.

Bob
tufcj

[jeepsr4ever]

I think Bob is right. When it stumbles does it feel like it is just loosing power or is it all at once? Sometimes you can put a larger carb on a motor only to have the stock fuel pump not keep up. Are you running a return line and is your fuel tank ventilated? I ran into an issue where the fuel tank vent was plugged and it was sucking gas from the return line and not feeding the carb well. This may or may not be the case in your situation.

[ironman_gq]

check the dizzy or timing chain for play. If the gears are going or the advance is going the timing can jump. Or it could be a break in the coil winding. when they get hot the connection breaks and the engine is dead until the coil cools down again.

[Mudrat]

Thanks all. I think I do need to get into the float chamber but for right now, I've re-routed the fuel line from the pump, back to the firewall, across, and up the fender to the filter and pressure regulator - pump puts out 9PSI (advertised) and the Webber won't take that (5-5.5 ?) - to the carb.

MC, the Webber has a return line off the bowl and the line is clear - you can hear it at the filler neck when feeding air back through the line and hte vent line comes back up to the cannister - didn't check that one though #-o . And, when cranking the engine (no coil wire) it'll put 8oz of gas in a water bottle in a hurry!

Double checked the dizzy cap and rotor, plug wires, coil (new ACCEL installed) not that the other one was bad, but...

Bumped the timing a couple degrees (to 11*) probably should have pulled it and looked at the gears, but if the gears were going then the engine is coming out!! A 4.2L cam drives the diz directly, and with only 4700 miles on the rebuild, I'd shove it up his ass!!

Drove it around for about 45 minutes with no problems. I guess we'll see tomorrow on the way to work at oh-it's-so-dark-thirty! 111!!!

[ed455]

Had the same problem. For me it was the coil. I installed it without a resistor and it would quit, then start back up a few minutes later. I chased the problem for a week before I figured it out. The coil would overheat and quit, after cooling down for a few minutes it would start working again. Finally, the coil quit altogether and I found the problem.

[Mudrat]

Had the same problem. For me it was the coil. I installed it without a resistor and it would quit, then start back up a few minutes later. I chased the problem for a week before I figured it out. The coil would overheat and quit, after cooling down for a few minutes it would start working again. Finally, the coil quit altogether and I found the problem.
Resister where??? What value? It's worth a look :-|

[ed455]

The ballast resistor to the coil. Ignition coils (except for hei) are supposed to run on 8-10 volts. Here an example of the resistor.

http://www.autozone.com/R,NONAPP6456/store,106/shopping/accessoryProductDetail.htm

[ironman_gq]

many new coils are OK to run at full voltage. They should specify weather a resistor is needed or not but Im pretty sure the tfi coil is OK at full voltage but not completely.

[jinpdx]

It sounds like its either the ignition module on the firewall, or the pickup in the distributor. I had the very same problem on several rigs.

[ed455]

I was running an Accel super coil and it DOES require ballast resistor. I don't know about tfi coil.

[hugh]

I had a similar problem on my CJ5 with a 258 a few years ago and it turned out to be vapor lock, an instant cure was pour some cold water on the fuel pump. I put an inline carter electric pump on my 7 in the hope that it would not happen ti it. So far so good.

[Mudrat]

Well, I rerouted the fuel line from the pump on the P-side, back to the firewall, over the D-side fender to the fuel filter back to the pressure regulator to the carb. I've got it all zip-tied in place - Does a "Rube Goldberg" job mean anything to anybody #-o Cleaned up a cold solder joint on the ignition wire (not the 'run' wire) on the starter relay and it hicupped on me once in a quick right turn (why I need to look at the float), didn't die though. I bummped the timing up a couple * as well - and lost 2 MPG?? The coil is already mounted on the P-side fender well away from the engine heat.

I did find a vacuum leak yesterday (after 120 miles) in the softball size vacuum chamber on the P-side fender. That got a squirt of RTV :mrgreen: Not sure why it's still there, I think it's for the vac disconnect for the front axle - but that all got plugged up when I installed the mechanical disco for the front end :? Lazy or forgetful - dunno which :oops: I haven't had time to crawl under, strip the wire loom and trace the lines yet. If it works right now, screw it until I get back.

Other than that, I've got another 200 or so miles on it ~80 after the RTV drill, with just the one oops before the strategic application of RTV.

I'm going to check the float and see how that looks. After that I'll get to the VAC line. :wink:

But the most pressing issue is when I was under the hood I found the u-joints for the steering shaft are shot (Part Number 56113.02)! I need to get that changed out ASAP before it fails hauling ass down the road!!

Bad news is I have to be in Japan on the April 16th :evil: But I need to get this sorted out and do a more professional job on the fuel line, right now it's all zip-tied to the wiring harness!! And fix the steering shaft! :shock:

[hugh]

Its costly but look at either the flaming river or borgesson steering shaft, they are miles better than the stock stuff.

[Mudrat]

iI looked at them, but definately not in the budget right now. Got a stock unit for $80 + freight from Morris 4x4 in Fl. Just couldn't swing the extra 200 clams right now :smile: It should last another 70-80K miles :mrgreen:

[donwag]

Had an 89 Wrangler did the same thing. It was the ignition control module.