87 Wrangler dies

[cdlongjr]

When I drove the Wrangler down 495 from Chester, Pa. a couple of weeks ago, she died 3 times before I got to the 12th street bridge. After the bridge, she ran fine. Tonight, she would die everytime I got over 50 mph, (about 52 mph @ 2000 rpms). Engine died, but would come back @ 40 mph, go up past 50 mph & die again. I had the same scenario all the way home. I made a right turn onto Red Mill Rd & she died completely. Started right back up & made it home. I have the 4.2 L & the Nutter by pass has been done, B&M auto trans, new Dura spark ignition module, new coil pick up, new coil, new fuel pump, new fuel filter, rebuilt MC 2100 from an Auto parts store,(121 venturies), new K&N air filter assembly. Oil levels are ok & just filled her with regular gas.
Any ideas what the problem might be?
Thanks

 

[SteelHeadz]

The question is , Is it fuel or fire that's causing the stalling. Start with the basics. Fuel pressure at idle and WOT(wide open throttle). Is there a misfire prior to the engine shutting down @50mph?

 

[cdlongjr]

Drove her last night with a 12v light tied into the coil. When she died, light stayed on, so I'm pretty sure it's not the ignition system. Shw will run at 3,000 rpms in park with no problem. I'm leaning toward the MC 2100 with 121 ventris. Mainly because the engine completety dies when making hard turns & hyas to be restarted. Last night when I shut her off she dieseled. Running Shell regular gas & the engine has been power timed.

 

[Bounty__Hunter]

Don't most run the 1.08 MC carb?

 

[cdlongjr]

Yes, most do. I ordered the carb for a 304, but this is the one I got & the auto parts store didn't have anyway to obtain a carb with 108s, (which they told me after the fact). I would have had to pay shipping on all the carbs until we hopefully got one with 108s.

 

[cdlongjr]

No missfire, cough or anything, just quits. I have adjusted the idle mix screws using a vac gauge to get max manifold vacuum. Now she bogs from a standing start.

 

[yo momma yj]

<Drove her last night with a 12v light tied into the coil. When she died, light stayed on, so I'm pretty sure it's not the ignition system.

no, that just means there's power to the coil, the coil itself can still have a thermal intermittent in the windings...check the wire from the coil to the distributor (I had 1 go bad), dist cap, ect...

this is electronic ignition and not points? if it's points shout back and I'll run down how to troubleshoot points.

if it were one cylinder dropping out, it would be a plug or wire, but for all to go at the same time strongly suggests an ignition circuit problem

< Last night when I shut her off she dieseled. Running Shell regular gas & the engine has been power timed.[/QUOTE]

dieseling is a bit of carbon or a metal nub glowing to provide an ignition source.

look in your intake and see if there's carbon on the butterfly...that says the EPA mandated breather is dumping carbon in the intake and that means the valve seats are fudgey and low compression.

if it stops spritz ether (or a teaspoon of gas) in the intake and see if it will fire...that says you have spark.

if it stops, you could look in the float bowls to see if it's empty (is there a float bowl drain?)...if so then look for a fuel delivery problem (pump/ filter/rusty tank ect...

the trick to diagnosis is to determine what all is there and what's missing

so far there isn't enough info to determine spark, fuel, or compression, but I'm leaning towards spark here, tho the carb mods aren't sitting well with me.

first step is determine it's not fuel...when it stops spritz some gas in the intake and see if it will fire then run out of gas in 2 seconds.

you could have:
a bad coil or wire
bad dist rotor
a pin hole in the fuel pump diaphram or rust in the pipe from the tank
a blocked float valve
a low float setting

narrow it down and report back.

 

[carnuck]

Is there a tach involved? I've had them short and kill a motor like that (happened on my '82 C20 with 454 right in the middle of rush hour last monday!)
What fuel filter do you have? The one with 3 lines needs the return line in the 12:00 position. Crud in the fuel tank will clog the screen till the motor stalls and the lack of suction will release the crud till you rev it again. (I put a filter in my fuel line before the fuel pump)

 

[cdlongjr]

She has a factory tach. I'll try an additional fuel filter before the pump. She acts like you turn the key off @ 60 mph, then turn the key back on @ 40 mph.

 

[cdlongjr]

At the suggestion of Carnuck, I should put a clear fuel filter before the fuel pump. Last night I installed one. Very little fuel coming to the pump. Tonight I'll turn the air compresor pressure down & blow the fuel line from front to rear & blow out the fuel pump, then install a new factory fuel filter & see what happens.

 

[cdlongjr]

Checked all the fuel system with a blow gun @ 10 psi. No obstructions or debris. Hooked everything back up & still no start. Removed the fuel line into the factory fuel filter & placed it into a liter bottle. Good fuel flow. Hooked it back up, no start. Removed the fuel line from the carb & placed it into the bottle. Damn thing started. Hooked the fuel line back up to the carb & she wouldn't start. Removed the line again & she started again. Hooked it back up & no start. Removed the return fuel line & put a rubber cap over the nipple on the fuel filter. She started & idled better than she ever has. Usually cold, I had to pump the gas pedal to keep her running. Not this time. What's the problem with the return line? Do I just cap the steel return line so she'll pass inspection? (They pressure test the fuel tank).

 

[cdlongjr]

I wonder if the canister plumbing may be causing my problems:
CTO (As you are facing the driver's side of the engine)
I have 2 ports on the left & 3 ports on the right
Right side
1st port closest to the engine has no hose to it
2nd port has a line from the vacuum line to the brake booster (has a tee in it)
3rd port goes to number 4 on the canister
Left side
port closest to the engine goes to the modulator valve on the transmission
other port has a line fom the brake booster

Canister (from firewall to the radiator
#1 to air cleaner base
#2 vapor from fuel tank
#3 tee with PCV valve
#4 to CTO, 3rd port on the right

NO vacuum to EGR valve

 

[SteelHeadz]

Hard call. It seems like the symptom is more so towards fuel flow. I wonder if you plug the #2 port Vapor to fuel tank vacuum line, and see if starts right up. Thoery: If the Vacuum in the fuel tank is in excess of what the fuel pump can supply the carburator, then the fuel flow will be insufficient through the lines. Just a shot in the dark.

 

[cdlongjr]

I swapped the carb with the carb off my 74 J-10 with the 360 CI engine. I was able to correctly plumb all the lines from the canister except the line closest to the firewall. It is supposed to go to the vent on the fuel bowl. My carb doesn't have that vent. I ran the line to the tube on the left rear of the carb, which goes into the air cleaner.

 

[SteelHeadz]

Is it running normal now?

 

[cdlongjr]

SHE"S ALIVE!!! Drove her 70 mph today. Combo of wrong carb & canister plumbing. I used both MC 2100s I had to make the correct one.