stalling at idle 1989 chev 305 k1500

Hello!
I have a 1989 chev 305TBI that will not idle in closed loop! stalls and
cranks right back up and stalls again. It will idle in open but has no
power and putting it in gear kills it.also turning the steering wheel
kills it.Runs fine on the road.. No codes.
Here is what i have done.
new fuel pump/ filter,tps,emc coolant sensor,IAC,dist module(old was bad
low rpm failed)new TBI gasket and cleaning,new egr gasket and cleaned
valve and checked,new O2 sensor,tryed known good map(no change)checked the
brake booster OK,all vac lines OK. acts like it loosing spark when it
dies?? dies so fast its hard to tell.I don't see the fuel stop comming
from the injectors thats why i am saying spark. The pick-up is real rusty!
bad rusty! I know the faster a Mag spins the more micro volts you
get.Question could the mags be so rusty that at slow speed the output is
too weak? It will idle at 900-1000.I am just lost as to what to check!
maybe Coil or ecm? there is 2 plugs on the coil what do they do? do they
go to the ecm or from it? I can't tell if its something getting hot and
failing.if so why would it start right back up? It will idle in Limp
mode!(back up fuel mode) (forgot that)I can put in gear and all that! Is
that bypassing the pickup coil? Hope someone can help!!I was told the
people here are the smartest on the internet! I do have a scan tool OTC
2000.any help would be great!Any Data you need just ask me!Thanks tom

woolfmaster wrote:
The pick-up is real rusty!
> bad rusty! I know the faster a Mag spins the more micro volts you
> get.Question could the mags be so rusty that at slow speed the output is
> too weak? It will idle at 900-1000.

I think you are on the right track. The reluctor on these distributors
can crack or otherwise weaken and cause too low input voltage to the
ignition module at low RPMs. This equals stalling.

> I am just lost as to what to check!
> maybe Coil or ecm? there is 2 plugs on the coil what do they do? do they
> go to the ecm or from it? I can't tell if its something getting hot and
> failing.if so why would it start right back up? It will idle in Limp
> mode!(back up fuel mode) (forgot that)I can put in gear and all that! Is
> that bypassing the pickup coil?

You aren't "bypassing the pickup coil" otherwise the engine wouldn't
run at all. Perhaps the RPMS stay higher when you jump the aldl (or
enter backup fuel mode with your Monitor 2000). Perhaps the fuel
charge is richer and easier to fire with the erratic spark output.

Get a wiring diagram or delve into the distributor to find the wires
coming from the pickup inside and follow them to the ignition module.
You can scope their output or check them with an AC voltmeter. I would
expect to see over .5 volt r.m.s. at cranking speeds (a figure I'm
basically guessing at, but it's close).

You may be able to get a fairly cheap reman distributor housing
complete with new reluctor and pickup at an auto parts store. It may
be so cheap that it's worth trying as a swap and hope option if you
don't want to diagnose the problem.

Toyota MDT in MO

Thanks Comboverfish!
I tested the pick-up coil today 850 ohm..500-1500 they said was good..I
drove the truck tonight and same old thing. at times it idled more than 5
sec. 10 to 15 and i watched eached time it stalled had that spark cutting
out feel...below 700 rpm. I will test the pick-up coil for output
tomorrow. about .5 rms ypu say. i will look for...I think thats right
500mv AC.One thing it did tonight was i let it sit (3 mins) as i looked at
the repair book and when i started it back up it was in open loop for maybe
25 sec (O2 cooled off i bet) and it idled jumped to closed and it stalled.
It's so hard one person to look under the hood and be inside to start it
and run out to look at a meter or the spark. I have a good coil(same year
s-10) i may try that next! lean fuel and weak spark?? Maybe!I remember a
ford i worked on that would stall and crank back up and it was the
pick-up(after they sold her two new brain boxes) when the pick-up got warm
i bet the ohms when sky high.But it was like this start right back up. My
gut says loss of spark!Thanks for the help! anyone else jump in!!

Checked the pick-up output was 230 mv unsteady 210-250...at cold
cranking... sounds low to me....anyone know what it should be??? thanks!
tom

Well NASA we have a FIX! was the weak magnets in the Dist. This was Gm
thing for cars and truck in 1989. here is the URL
http://www.mightyautoparts.com/pdf/articles/tt71.pdf
tells all about it.. Thank you all for your help! Tom