You know all those idle stop screws have been messed with over the years. And that can be a reason why you can't get the idle voltage where you want it. I would adjust it if it needed it.

 

Hmmm.. So your talking about the fast idle screw?

 

I got messed up in the last post and forgot what you are working on. You have a carb, I got sidetracked on the EFI version.

Your computer style carb setup is probably like the one on my 84. It had the 2bbl 2150 with the computer, and the idle was controlled by a little DC motor. The setup procedure for that is a little complicated. Your carb should have a mechanical stop way down low that keeps the butterflies from sticking shut, and then you have an adjustment where the whole complete dc motor assembly will move back and forth.

 

Not looking for Voltage but continuity. It should read near 0 on the Ohm ( Ω ) or Continuity setting on the meter.

 

If it’s supposed to have a DC motor it wasn’t on here when I bought the truck.. My carb has the TPS and a mixture control solenoid

 

Okay! Well on the continuity setting on my volt meter I’m getting the 0.00 when I test the wires

 

I see you live in Georgia. Do you have inspections in your area? If it were my truck, I would get another distributor and install it, another carb, and get rid of all that junk and the computer. It happens over and over, the 300 sixes have it really bad. I took the computer system off my 2.8 v6 and it runs way better than it did with all that junk on there.

 

And when you test to the ECT or MAP ?

 

Definitely don’t have inspections... Ive thought about doing that, I have a couple of non feedback carbs already but I don’t know anything about it... Ive read some forms but sometimes it seems easy and others it sounds complicated.... Ive also thought about just gutting the 85 and dropping the motor and all from my 95 in it.. But I’m undecided I just know I’ve run in circles with this truck and haven’t gotten any closer to fixing it!

 

It sounds like you keep trying to check / fix things that the computer is trying control but not getting anywhere as you cant see what the computer is trying to do.
Do like others and throw that computer system in the trash can and go with parts YOU can make adjustments to and see the out come of.

You say you have 1 or 2 non-feed back carbs I would take the best one, throw a rebuild kit at one and install it on the motor.
We already know even not changing the dist. if the carb was bad it will run better just a little low on power because the timing is locked in and will not advance.
At that point you will know if the issues was carb or not.

If the truck had a real computer that was not 100 years old and you could test and get parts for I would say try and fix it other wise trash can it!
Dave ----

 

How hard is it to get rid of the computer, do you really only replace the distributor and put a non feedback carb on? I was under the impression there was more to it so that’s why I never looked into to start with.

 

You also need to wire up the ING box on the inner fender.
You can either get the wiring from the junk yard from any truck 80 - 86 v8 or six or Painless makes one for $$$ or some go with HEI type dist and you only need to run full 12 volts to it but ......... the wire that did this stock is a resistance wire so you need to wire in a relay to supply 12 volts.
But yes it is just that easy, do a search for DSII swap for more information.
Dave ----

 

That's all there is to it. There is a normal engine under all those wires and hoses. It just needs spark and fuel to run.

 

Would not just go tearing everything out yet, the ECU is communicating and the MAP code has been resolved finish ringing out the wires and see if it is just a simple wiring fault. If it ends up being an ECU issue then ditch it.

 

When I rewired my truck, I ended up chasing my tail on a TPS code because I mistakenly switched the black and green wires. Your issue is either 1. the sensor, 2. its wires/ground, or 3. the computer. That is about it. Make sure ECM ground pigtail (right on the neg battery lead) is connected. --Make sure you have good system ground as this can cause all sorts of ghost codes, is block grounded well and is body grounded as well?

This should be first above all, what is base timing set at? Incorrect timing can cause popping through exhaust and all sorts of issues, with engine fully warmed up, pull SPOUT connector and verify base timing is dead on 10 deg BTDC, if not set it there.

Vacuum leaks! Do you have cracked, missing, uncapped, vacuum lines/ports? Bad carb base gasket? Loose PCV? Hissing brake booster? Vacuum leak(s) can cause popping through exhaust as well as cause the vac system not to have enough strength to actuate EGR.

Also, mixed up plug wires can cause this, verify plug wires are in good condition (not cracked and less than 12k ohm per foot), in the right firing order, and routed neatly.

ECT (engine coolant temperature) sensor is a really easy one, it only has two wires and without it, it will run horrible. Can you see if you are getting 1. the +5 VDC reference voltage 2. signal return ground to computer (Matt which pin is sig return?) 3. measure its resistance cold (just the two pins inside the sensor, not the wires) and hot. Resistance should go down hot.

Check EGR solenoid with meter, is +5 VDC reference voltage there? Is signal ground wire to battery ground less than 1.5 ohms? Is signal ground to computer pin connector 0 ohms? Check back probed voltages of EGR solenoid in various running states and resistance when off.--you can find these specific values online/ in book.

EGR is also straightforward, use a miti vac to pull vacuum on its nipple, does it hold a vacuum for a minute? IF not diaphragm is bad.

Now, with engine fully warmed up at 1.5k-2.k RPM and observe EGR valve pintle--Do you see it moving? If not, remove hose and hook up vac gauge to EGR vac hose and run engine again, do you have vac at gauge? If not, vac line is broken or EVR solenoid is not giving signal to open vac.

With EGR removed --Are the ports full of carbon crud inside?