Good evening all. I need some spiritual guidance, if you will. I have an 84 Blazer 2wd with the carbed 2.8/700r4 combo.

The truck will turn over, but will not start. A week ago, I did a basic tuneup on it (plugs, wires, dist. cap & rotor). Afterwards I started it up & drove it. It drove fine. I later go to leave and it wouldn't start.

I detirmended it wasn't getting spark. It's clearly getting gas in the bowls. I then replaced the coil and the control module, being careful not to cross any plug wires. No luck. Next I ran some tests on the main power wire to the coil and going to the control module and they all test good at +12 volts and switched polarity when the ignition swich (cylinder) was on.

Since that tested good, I went to the pickup coil & distributor next and replaced those making sure it was properly clocked. No dice. I even went as far as drop in a larger battery and did the big 3 upgrade to insurethe systemwas getting proper voltage.

At this point, I'm stumped. I've replaced all the items needed (as far as I know) to create spark.

Does anyone have any ideas?!? This is getting to me, lol. I'm ready to take it to the shop, but something is telling me that it's something simple. The truck ran good prior to this, so I don't believe it was mechanical failure and I'm sure it's getting gas.

Any help would be greatly appreciated.

Thanks.

84

 

I'm trying to remember if your truck uses the old capacitor discharge ignition system or if it electronic spark actuation. You said that you replaced the whole distributor? Did you swap any parts over? Was the replacement distributor new or used?

 

As far as the dist is concerned, it is a new unit (well reman) that came with the pickup coil & control module installed. I originally replaced the control module, but the distributor came with another one, so I just used it. I didn't have to swap anything over, as far as I saw. I simply had to run my lead from the ignition coil and plug it in to the new module and pop on the rotor and then the cap.

As far as the capacitor discharge, I'm not sure. I looked around to see if there was the little capacitor in the valley of the distributor (similar to my v8 HEI setup on my full size Chevy truck) and there was nothing there. I'm assuming you're refering to the capacitor they used to help eliminate radio noise on the early style setups. Mine doesn't have anything like that.

It's a basic system from what I can see. There are only 5 wires for the spark side of things.......large pink wire that brings power in from the ignition switchto the ignition coil. From there you have a small pink and small brown wires which runs to the control module. From the control module you have a green and a yellow wire that runs to the pickup coil. The unit is self-grounding. Thats it. I'm stumped at this point, since there's nothing else left to replace on that side of things and it seems to be getting voltage to and from the ignition coil.

 

Also, if it makes any difference, it is the vacuum advance setup. The new distributor also came with a new vacuum advance already installed as well.

 

Big 3?
Battery, alternator, starter?

Just becuase the starter turns the engine over doesn';t mean its turning it fast enough. Get it tested.

Not spark at all, or just not in time?

Got a security system?

Verify your plug/coil wires are all the way on.

Since it ran with after the tune up, I gather the tune up was done correctly.
Retrace your steps though, maybe you left something disconnected.

 

The alt is fine, batt is new (and I had my batt charger on it as well), and starter turns over just fine. Theres no security system on the truck whatsoever. The plug wires are plugged in as required.

I did do another spark test today and it is now getting spark. When I first did the test it wasn't getting spark, but I'm not sure if I performed the test properly at first. This was before I replaced the distributor & pickup coil tho. I did the old school test of taking off a plug wire and putting a spark plug in it, turn the motor over and see if the spark jumps. When I originally did the test, I don't believe I had the plug close enough to a ground for it to arc. This time itarced with no problems.

I'm positive it's getting gas, which leads me to believe it's getting too much gas. I noticed when turning the engine over, I would smell gas whether I gave it gas or not. I checked my oil and it smells like gas, which tells me that gas is running in the cumbustion chamber and flooding it out whether I give it gas or not. I believe I now need to either rebuild or replace the carb all together. After looking at prices, I'll be rebuilding for the moment lol. No sweat, I'verebuiltcarbs before.

I also gave a call to the person I bought the truck from and he mentioned that he had the needle valve stick on the truck before and it had the same problem (turning over, but not starting). He then rebuilt the carb, but this was some years ago.

That's where I'm going next.

 

i didnt really read any of the posts except the first one, so im sorry if im repeating something or if youre already past the no spark problem. my dads "project" isnt a blazer but the coil was getting grounded out somewhere causing no spark out of it,yet there waspower to the coil. that might be what the no spark problem is. again, sorry if someone already mentioned the problem or you fixed it. im just throwing in a little fun fact

 

It's funny you mentioned that. I was curious about that as well. At first I tried running a small ground jumper wire from the negative terminal to the disc pack around the outside of the coil. It didn't make a difference in it starting. I did find that it have proper ground tho. I was able to put one end of my test light to the + terminal and the other to the discs on the coil and it lit up fine.

Thanks for the input just the same. Right now I'm just waiting on the carb to get here. Autozone sells them from 350-500 with a 3mo warranty depending on which model you have. I found a place in Orlando (Carburator Exchange) that sells them with a lifetime warranty for $200 shipped with exchange. They also include free core shipping on the return trip. Sounds great, but I ordered it Monday evening and they still haven't processed my order nor collected the funds to do so. I'm assuming their just swamped right now, but I need this thing running asap. I'll keep yall posted. Thanks again.

84