toyota231

I know these show up all the time but I've got a problem that is just killing me to figure out. Now as I explain keep in mind I'm working alone so some tests are hard to do. 1980 4x4, 20r. A little back story, truck ran one day (never really ran great due to old factory carb) next day it wouldn't run. Parts I've replaced and have less than an hour run time total: distributor, cap, button, plugs, wires, gm coil, ignition module, weber carb, fuel pump, fuel lines. Truck has been "de smoged" down to one line for the distributor.

I had the truck to where it would start and try to fire up but just wouldn't quite make it. I purchased an airtex electric pump from my work (advance auto) because the factory pump wouldn't show pressure on a guage, then with the electric pump I was getting 3.5 psi but still would try to fire un successfully. Then all of a sudden no spark at all
Now I have voltage going into the ignition module, power on both sides of the coil, but no spark on the coil wire, no voltage showing on the wires to the distributor with key on. I swapped back to the factory igniter and coil still nothing.

My questions are
1) could someone please explain the operation of the coil and distributor (voltage transfer, when it happens)so I make sure I understand? Keep in mind I can't test while turning the key cause I'm working alone.
2) the air gap on the distributor seems to be right and its a new reman distributor so is there anything else there that could cause no voltage between the coil and distributor with key on and no spark.
3) what else would come to mind to check? I'm at a loss, seriously I'm losing my mind with this freaking truck.

Any help would be appreciated. I can't view the factory service manual due to only having my phone for interweb, wish I could so maybe I could see any and all tests that could be done. I don't usually post like this asking help but I just want the dang truck to start up.

mwisham

There is a company in Tenn. called Dewey Unified Ignition ( DUI ) that makes HEI distributors to fit almost any engine. It only requires one hot wire from the ignition and one vacuum line. All the electronics are in the distributor. Costs about $200. I put one on my 1980 20R and I love it.

toyota231

Thank you for that info. I will check them out.

msane99

I've had them try to run when they are a tooth off on the distributor. I'd confirm top dead center first and for most. might be 180 out. might be one tooth off. sounds like timing first off.


no spark @ all might have smoked the igniter. check fuses, check fuse-able links @ battery (wires coming from green plugs @ battery) actual fuse-able links are just wires closest to battery upstream of green plugs, but as long as you are testing on downstream side you should have voltage) battery side will show voltage regardless has to be downstream of those green plugs..

should have 2 vacuum tits on distributor inner one should be capped or ran to intake manifold beside power brake vacuum nipple. outer one does the advancing as throttle opens, therefore its the one that goes to weber carb.

if its desmogged right those are the only three vacuum lines that should be present. 2 distributor lines and one to the brake booster. everything else should be capped.

if egr is still on truck (hooked up or not) whack it a couple times on the diaphragm on top to seat it well. If they are nasty they can get clogged open sometimes whacking them sometimes will close them up. They bleed serious amounts of vacuum when they are stuck open.