90 s10 4.3L just stopped dead

This unit is connected to the truck through the two wires ( a white and a pink ) coming out of the distributor going to the coil. When installed the white wire from/to dist./coil is cut and the white wire from the 5200 is spliced to the cut white wire going to the distributor. The other end of the white cut wire ( to coil ) is spliced to orange wire from the 5200. The red wire from the 5200 is 'tapped' into the pink wire. The black wire from the 5200 goes to ground.

Do the following:

The orange and white wires from the 5200 should be unwired from the trucks white wire(s) and then the trucks white wire(s) needs to be spliced back together. The red wire from the 5200 needs to be removed from the pink wire on the truck. ( makes sure the pink wire is still unbroken). The black wire from the 5200 just goes to ground so you don't have to do anything with that till you go to throw out that msd box.

It took me longer to type this than it will to remove the unit.

Thanks for the info! Did see their web site, MSD's, and it doesn't recommend using their MSD model 5200 with GM HEI ignitions. So I hope the truck owner can now be convinced to yank the thing. I have looked to see where the wiring does go and it is seemingly straight forward as to getting it out. Once out, I still don't think the truck will run, as I believe something shorted under the dash from what arcing noise he claims to have heard from time to time.

Now I got to figure out how hard it is to get the dash out to get to the wiring bundle to check that out and get a clear look at the computer, etc. Wish he'd spent the bucks on a Chilton or Hayne's book. Nothing like being in the dark!

Inside the distributer, there should be a "pickup coil". This coil is mostly flat, and goes around the distributor shaft. I had to replace two of them, one for a guy at a RV camp ground, the other one was at an auto repair garage.

To replace the coil, you have to remove the distributor cap. Remove the hold down bolt (and fork) and remove the distributor. Disconnect the battery, lock it in park, don't let anyone move the engine in any way. Note where the rotor points when you pull the distibutor. You don't want to lose your timing.

At the base of the distributor shaft is a worm gear, held in by a roll pin. Knock the pin out, pull the gear off. Slide out the shaft (which has the rotor on the end). Now you can remove the couple small screws that hold the pickup coil. Unclip one or two small connectors.

Install new pickup coil, and reassemble backwards of what you just undid. YOu'll have to reset the timing with a timing light.

Comptuer under the dash? My 98 has a box with a lot of wires on the passenger side fender, under the hood. Over the passenger front wheel.

The distributor pickup coil is a good guess.

my 89 s10 ( same body stle as a 90 The computer is under the dash to the right of the glovebox,, Mounted on the underside of the Dash and Not on the cowl

Storm> Comptuer under the dash? My 98 has a box with a lot of wires on

Finally the truck owner 'allowed' me to disconnect the MSD 'hot' box, model 5200 which MSD says is NOT recommended for HEI systems such as this S10. Reconnected ignition wiring as from factory, started right up. Never should been in there, but since we didn't know what it was, we left it as was until exhausting almost all other possibilities. I wanted it out days ago after reading their web site on this product.

Did we do anything wrong here? Timing seemed to change a bit from the 4 degree advanced timing we set prior to the reconnection of the EST wire.

Don't have a manual to work from and so don't know the exact steps to get the timing just right. At least it's running and sure starts WAY easier. Thanks to all for the positive helpful advice & tips!

Brown wire inside the truck cab just below the HEATER on the passenger side.. may have to Raise floor mat. Break the connection then time it to 0 with timing light

reconnect the wire . The wire may be BROWN with white stripe.

Does reconnecting the brown wire, after timing it to 0, alter the timing advance away from 0, (zero)?

Forgot to ask, is the vacuum advance line supposed to be yanked when setting 'zero'? I believe so, but want to be sure.

Follow the directions on the emissions label under the hood of the truck, it will tell you what to set the timing at and what connectors to disconnect to set the timing.

To answer his question asked twice now, yes the timing will change when you reconnect the wire. What your doing is setting base timing.

Whitelightning

If there's a brown (EST) wire AND a vacuum advance, something is not right... If there's a vacuum advance, something is not right...

Just want to be sure here. All I do is set the base timing to 'zero' with the vacuum hose/tube disconnected & the EST wire disconnected also, right? Then I hook the EST wire backup and I'm done, the computer then does the advancing, right?

YES

I donnot see a vacum advance line on the 89 4.3

There is no Vaccum advance on the 4.3

The Brown wire is connected to the computer and the computer does the advancing

LMCTruck.com says there is a vacuum advance for the '90 4.3 S10. I pulled a tube/hose that sure had a sucking sound once it was removed. Anyway, I did set base timing with it removed and put it back afterward. Without a book I'm assuming it was a vacuum advance.