1985 C20 350 Won't Start

[Metallifan]

Hi, I'm new to the forum.

 

I picked up a 1985 C20 2 wheel drive 350 a couple days ago and I've been trying to get it to start.

 

This is the first carbed vehicle I've ever owned and I know nothing about them.

 

It will crank all day, and I've tested for spark at both the wires and plugs and I'm getting spark, but it's weak.

 

I've tried putting starting fluid in the carb and it still won't fire.

 

I want to diagnose the issue before I throw parts at it.

 

The previous owner says it started in the fall but ran rough then died. He says it needs a new carb due to a vacuum leak, but it did start.

 

What are some diagnostic procedures I can run through to figure this out?

 

Thanks for any help.

[grampadirt]

I think the first thing I'd do is a compression check on the cylinders,it'll help give you an idea on which direction to go.

[Metallifan]

Compression is good and the head gaskets are brand new. I messed around with it with a buddy of mine not even 5 minutes ago and he suspects the pick up coil or ignition module or both.

[grampadirt]

I was going to suggest the ignition module as well.One went bad on an old '77 GMC I used to have.Make sure the connections to the HEI coil are good also.

[Metallifan]

I replaced the plugs, wires, cap, coil, rotor, and ignition module. It still will not start. Any ideas? Things I can check? My next though is the pickup coil but I have no idea how to remove/install that.

[Squirrely]

_{Did you set the choke before you started cranking this thing. No choke, no fire.}

[Metallifan]

It has a Quadrajet carb that has a vacuum choke which I assumed was automatic.

 

As I've said, I've tried putting starting fluid in the carb and had a friend hold the choke open while I cranked it. It refuses to fire.

[Squirrely]

It's not quite as automatic as you think. You still need to manually set the choke it by stomping the gas pedal to the floor once or twice. Do that then crank.. see if it will even sputter.

 

The vacuum leak is usually around the throttle shaft. the butterfly seals could be bad, or the carb body could be worn. Regardless, you need to set that thing at full choke to start.

 

Check EGR to make sure it's not stuck open. Are you getting fuel to the carb? Are the floats set correct? Are the jets plugged? Is there water instead of fuel the bowl?

 

I know you think dumping starter fluid in it will make it fire, but if it's gulping air, then it will never light.

 

 

 

 

Welcome to the world of Carburetors! I actually miss those things.

[Metallifan]

I have no idea. I don't know anything about carbs. Guess it's time to learn. I'm about to just buy a new one...

[Squirrely]

Get your learn on first. Then you can pick apart that old one and try to find what's up with it.

 

I've rebuilt a lot of carbs and I understand the frustration.

[Metallifan]

Where do you suggest I start? I don't even know what I'm looking at, these quadrajets have so much crap coming out of them.

 

If I set the choke and it still doesn't start, what should I try next? Where is the EGR valve?

 

If I do buy a new carb, what style choke do I want? I'm guessing hot air since I'd assume that's what it has factory. Would electric be better?

[Squirrely]

youtube and google. Tons of learning on there.

 

 

I always went with a manual choke. I got tired of the so called auto chokes failing and killing the motor.

 

The egr is on the back of your intake manifold, round lookin thing. When they go bad they usually get stuck open.

[Metallifan]

Replaced the carb today. Still won't start. It will give a chug like it's about to fire a few times, but won't fire up. Not sure what to do at this point.

[Squirrely]

Maybe your compression is shot.

 

So you're getting fuel?

Fire?

 

next is compression.

[desrtrat]

first i would check to see if your getting 12V to the distributor when your cranking it over. also check your base timing, and TDC on cylinder 1 and excess play in the timing chain. if all is good it should start..

 

good luck