Dies: taking load off engine by clutching for light/turn

[MorToy]

Starts like a champ. Idles great. Get going and up-shifts are no sweat. Goes a ways, approach a light or 90 degree turn. Down-shift from 3 to 2. Normal. Push clutch in to come to stop or slow way down for turning corner and it dies. Good and dead. No sputters, no stalling, no jerking. It just stops running. I know it dies because the dash idiot lights come on.

Here's the rub: it's sporadic. When it has a spell, it is consistent--i.e., it will do it it until I stop and let it sit. These spells, however, do not occur every time I take it out. It overwhelmingly runs fine.

First happend when I had it on back highways, traveling for an hour at 55 MPH going fishing last summer. Went to slow down and turn on side road and it died. It continued to do this until I got home. Tightened loose ground, swapped dizzy. Ran great for months.

Second spell, winter. I approached a light on a frontage road (going about 45 MPH). Slowed down, down-shifted from 5 to 4 to 3 to 2 and when I clutched and braked to stop for the light, it died. I had been driving for 20 minutes no issues. Stopped for ten minutes, let it set, was able to drive home no problem. Ran normally for weeks. Noticed my stock negative cable was pretty shabby so I replaced it.

Was thinking maybe it was a speed thing because I mostly do in-town driving and it did it after 45MPH speeds...until...

Third spell (tonight). Driving in town, residential streets (25 MPH). Started from cold. Ran it no more than 1/2 mile and it died the first time I took load off engine by clutching for a stop at a light. Did it at all the turns onto streets as well. Let it set for five minutes, drove it another couple miles, same issue. Let it sit 15 minutes, drove home fine.

When it acts up, I can keep running by revving engine. When it dies, I can restart it normally, but have to rev it when I let off clutch into 1st. After that, shifting *and* down-shifting are no issue *until* I clutch to stop at light and take the load off the engine.

Thoughts? The dead-as-doornail and sporadic MO screams electrical short--but why only when I take load off engine and not anytime else? No tach, so I can't tell you exact RPM when it does it.

[dlb]

mortoy, it sounds like it downshifts fine and only dies when the clutch is disengaged (clutch pedal pressed down) and you are stopped or almost stopped. is that correct?

i had a somewhat similar gremlin in a '91 vw passat wagon i had. i could be in coasting down a road in neutral and that would keep it running but once the car slowed down, it would start to die and finally did when stopped. took a long time to figure it out but there wound up being a corroded/barely broken wire in a plug that attached to the dizzy. my guess as to why it was so intermittent is that the car vibrated differently in different running conditions: maybe the rolling of the car made the wire ends vibrate just slightly so that they were close enough for most of the time, in effect closing the circuit. so i would look at all the pertinent wiring you can see, pulling back any boots or whatever to thoroughly expose as much as possible, and looking for anything suspect.

[ARCHINSTL]

This is prob out of left field, but - could there be some fault with the clutch/starter activating switch or its wiring?
Or maybe something in the steering column rubbing against ignition wiring?
Tom M.

[MorToy]

I know, right? I hate chasing small electrical shorts. Let the hunt begin! I'll post my findings.

dlb: Yep, only when I push clutch pedal in and as I am rolling to stop.

PS: It did it again this morning.

[Petros]

first check for vacuum leaks and all your lines are routed properly, than make sure your float level is correct through the site glass on the front side of the carb, and you might also check for a weak spark. Also, there is a vac operated throttle stop on the side of the carb oposite the throttle cable side that can cause it to stall right after returning to idle if not adjusted properly, not a difficult adjustment at all, the the test is simple enough, see the FSM.

I have seen a marginal coil or pick-up run okay at times, and get weak after it warms up and cuts out at low speed. with an irregular spark at idle it could die. see how strong and regular signal you get with a timing light. If irregular at idle it could be the coil or pick-up. see FSM for test instructions on the coil and distributor components. There used to be places you could take a distributor where they could test its functions in a bench mounted machine, but most of those places have gone away. Perhaps a local hot rod shop that still services and sell parts for older points type distributors might have one of those machines.

Good luck.

[MorToy]

Thanks guys, I won't get to testing until the weekend. I'll let you know.

Petros: your suggestion of vac operated throttle stop perfectly combines my dad's suggestion with the thoughts of an older mechanic I ran this by. My dad's first thought was vacuum. Mechanic suggested the throttle was closing too quick (he first thought it was throttle positioner until I told it was carbureted engine).

Tune in next week!

[dlb]

it could well be the throttle positioner (that is the throttle stop petros mentioned above) but it would be odd that the engine would die only when it's stopped and/or almost stopped rolling. the TP operates the same way regardless of whether the car is moving or not. i'm curious to see how this pans out.

[irowiki]

Hi, I have this problem too, but only in very specific situations. Some in this thread know I have a Frankencel that does some funny things because of bad owners over the years.

If it is cold started and the temp is say, under 40, within the first five minutes it'll die when I clutch for a stop sign. The same stop sign every time on the way to work, it is on a slight downhill. Clutch in, bam. Maybe I'm not downshifting enough? Not used to manuals yet. I figured it was just cold and maybe I need to idle when I start and let it warm up, or perhaps I need to choke it some. It does not stall once it is warmed up unless I stall it on accident

The cable/wire you're talking about, is that the cable from the electronic ignition going to the distributor? I haven't replaced that or the spark plug wires yet, perhaps I should.

[Jarf]

While it might be a long shot there is one other thing to consider - sludge in the float bowl, usually caused by rust in the fuel tank, when they rust it is a very fine silty type of rust, running the tank low will increase the possibility of silt getting into the carb.
When braking or decelerating hard, the sludge can block needle and seat.

If you suspect this may be happening, there is a hack way of diagnosing, swap #2 & #3 spark plug wires, fire it up, it will tend to backfire up through the carb, make it back fire a couple of times (by blipping the throttle) then correct the plug wiring, if she runs good, you know you have a silting issue in the carb.
Just another thing to consider.

[MorToy]

Sorry for delay...just got to checking things out. Started simple--checked timing and realized my vac advance on the dizzy was shot. Swapped it out with spare and engine is advancing. I am going to see if the problem pops back up rather than monkey around with more things. I did look for loose/frayed/missing wires around the dizzy and elsewhere. Did not see any. (irowiki: the cable I referred to in my first post was the main negative cable off the battery). Jarf: interesting idea,which I will file away for future.

I will drive for awhile and give an update. Cross fingers it was vac advance.