pastorjared

ok, Update.

I've now replaced:
Fuel Pump
Fuel Filter
Throttle Position Sensor
Spark Plugs (not wires yet)
Rebuilt throttle body
Distributor

I started the truck and it started ran for a bit (rough) and adjusted the timing a bit. then it started running rough again.

So here's what I did and I can't figure out what's going on. I connected my timing light to each plug wire to see if it was getting spark on each wire. my 2,4,6 and 8 wires were getting consistent spark while my 1,3,5 and 7 wires were getting intermittent spark. Is that the timing? or is it something else? I thought it was strange that one side was fine, while the other wasn't

Gumby22

Lots of possibilities why you’d be seeing the difference between banks.

Is the spark control circuit unplugged while you’re checking it?

Is the timing light probe positioned at the plugs or the distributor? If it’s at the plugs, it’s possible the wires are grounding out.

Firing order is 1-8-4-3-6-5-7-2.

Are you sure you didn’t mistakenly installed the distributor a tooth off and/or 180 degrees out?

pastorjared

No I havent unplugged the spark control circuit. I unplugged the Automatic timing.

I've checked the plug wires and they are not grounding out anyhwere.

I think it is entirely possible the distributor is a tooth off. any tips on getting it lined up correctly once it's off like this?

Gumby22

1) We’re probably referencing the same thing, but for clarification, what are you calling the automatic timing?

2) The primary challenge (for me anyway) is getting the oil pump driveshaft lined up. What I’ve learned to do is to slightly advance the pump shaft with a long screwdriver and once the distributor is initially meshed with the cam gear, rotate the engine using the crankshaft bolt and the distributor will drop in place once it’s lined up, then I’ll back it up to TDC and double check the rotor alignment. All the plugs have to be removed to do it this way but it works.

Gumby22

Here’s a pic of the spark control circuit connector location (courtesy of a previous thread). As long as this is disconnected the spark timing is only adjustable by rotating the distributor.


ECM spark control circuit connector circled in red

pastorjared

oh yes, that’s unplugged

pastorjared

ok, so after changing:
Spark Plugs
Fuel Pump
Fuel Filter
Throttle position sensor
Distributor
Rebuilt the throttle body
O2 sensor

It ended up being a bad Ignition coil. apparently, it wasn't giving enough spark to give the distributor enough juice to work properly.

It was also the next thing I was going to replace but thought "No it can't be that if I'm getting spark!"

So I took it to a mechanic, and he hooked it up to the computer and replaced the coil. The timing was off just a little bit, but now it runs like a champ!

thank you guys for all your help!

Gumby22

Good to hear you got it figured out, but I am curious how your mechanic figured out it was the ignition coil by using a scanner.

OBD 1 systems (pre-1996) are very basic and primarily control/monitor emissions components. Codes can be pulled and a certain amount of live data can be read, but it doesn’t have any capabilities to monitor the ignition coil. Even modern systems can only monitor the primary circuits.

pastorjared

That’s a great question that I have no answer for. He initially thought it was the computer because his system wasn’t connecting to the truck. He had to get a different system so the computer would actually read. I didn’t ask him what codes came up.