This one is a little odd.

I was driving on the highway today, got off at a ramp, everything seems fine, but the truck stalls.

After this point, and for several miles worth of driving later until I got home - I have to double-pedal the sucker to keep it running when in gear.

If I want the thing to stay running after I shift into reverse or any forward gear, I need to step up to about 1300-1500 rpm.

At idle in park, if I allow rpm to drop below say 1050 rpm, truck quits just like turned off at the key. Same if approaching a stop in gear without foot on the gas. Quits just like the source of ignition removed.

The engine is pulling a decent 20" of vacuum. Transmission shifts fine, although it is often a a little slow to start out in D from park (and has been for long time). Otherwise fluid level, and shifts are smooth, kickdown works fine.

The truck never did this before today, and it is not an intermittant issue now. Does it everytime.

I swapped on a known good 2150, and it works the same way.

I intend on checking out the vacuum modulator tomorrow, but I don't think this is a tranny issue.

Nothing I've owned has acted quite like this, so some of the usual suspects for ignition components or vac leaks etc aren't seeming like a fit..

I have a pertronix distributor in a box. I might put that in tomorrow to remove several of the ignition components as currently set up (DSII) from suspicion.

Any thoughts on this would be appreciated.

 

Very strange. When it dies, are you able to re-start it right away? It almost sounds like a rare fault inside the ignition module.

 

I can start again right away, but need to open the throttle to do so.

 

was this problem resolved and how, my85 is doing the same thing

 

was this problem ever solved and if so how-my 85 doing the same thing-any help would be appreciated, thanks jim

 

I'm going out shortly to install new distributor and check vacuum modulator on transmission.

The distributor i am replacing stock with is a pertronix unit that has internal coil. eliminates some of the stock ignition components.

 

keep us updated

 

Ok, this one goes in the hall of shame.

The magnetic pickup somehow worked it's way loose and was dancing into the reluctor wheel, which had about .250" ground away! So even though this was symptom-free somehow for quite a period of time, basically the signal became too weak at lower rpm which led me to this point.

Pertronix unit in place, which is just like any distributor, except that it only has two wires, one for each positive and negative primary terminals of the coil. "Ignitor 3" model.

This has easily adjustable mechanical advance limit, rev limit and different rate springs, overall a nice unit. Works nice right out of the box.

I had an issue with this truck when I bought it, removing emissions gear and dealing with the distributor which had frozen in the block. I should have replaced it then, apparently.

Thanks for reading.