Getting the 69 C20 to run after sitting

[Gruman]

After sitting for 7 years, I got the truck running and hauled back to my place. Have had it running a few times since then just fine. (it would start and idle great) Now it wont start. I believe the 350 motor is from a later truck, 78 to 81~ish with a 4 barrel Quadrajet on top. (OE I'm guessing) Everything pretty much stock.

Here's the problem: It wont start and run. I can pour gas down the carb and it will run until it uses up the gas. I've got fuel to the carb, (fuel pump works) checked the fuel filter (clean) but just cant get it to stay alive after priming it with gas. Fuel line has plenty of pressure, but its like its not getting through the carb.

I'm pretty fresh with carbs so anyone have any suggestion on where to start?

[BLT gmc]

The carb will need a tear down and rebuild. I suspect there are minute peices coming from the tank, fuel lines and possibly the carb itself. Good luck, Bruce

[geezer#99]

Don't jump to that rebuild it just yet.
Check the fuel filter in the inlet of the carb. Remove your fuel line. THen remove that big inlet fitting. It needs a 1 inch wrench or crescent. Unscrew gently. It has easily damaged fine threads. The filter is inside it.

[flashed]

If you have not done so already ,check your gas tank for rust ans dead gummy gas and also check the small section of fuel line on the gas tank ,it may be cracked .

[68gmsee]

Is the gas in the tank fresh? If not, you're introducing contaminated gas into the carb. If the gas is old in the tank, mixing in fresh gas won't help much after 7 years of sitting. A removal and cleaning of the tank is required.

My 68 sat for a couple of years and before I started the rebuilt engine, I removed and cleaned the carb, installed a new filter and used a one gallon container of fresh gas under the fuel pump with a short piece of fuel line going to the inlet side of the fuel pump. This insured I was not burning old, varnished gas which can look like engine problems when burning it.

[Gruman]

Originally Posted by geezer#99

Don't jump to that rebuild it just yet.
Check the fuel filter in the inlet of the carb. Remove your fuel line. THen remove that big inlet fitting. It needs a 1 inch wrench or crescent. Unscrew gently. It has easily damaged fine threads. The filter is inside it.

I have checked it already, seems fine.

Originally Posted by 68gmsee

Is the gas in the tank fresh? If not, you're introducing contaminated gas into the carb. If the gas is old in the tank, mixing in fresh gas won't help much after 7 years of sitting. A removal and cleaning of the tank is required.

My 68 sat for a couple of years and before I started the rebuilt engine, I removed and cleaned the carb, installed a new filter and used a one gallon container of fresh gas under the fuel pump with a short piece of fuel line going to the inlet side of the fuel pump. This insured I was not burning old, varnished gas which can look like engine problems when burning it.

The tank was empty when I bought the truck. But that doesn't mean the lines were clear.

I tried unhooking the gas line from the carb and cranking it and plenty of fuel was shooting out of the line so the problem (I think) is going to be in the carb somewhere. Any other suggestions before I have to do a rebuild?

Remember, I had this thing running fine a few days ago...

[Gruman]

I yanked the carb off and will be going through it soon. I have a rebuild kit on the way.

Heres why:

Well, I tried to get it started again yesterday and still having same problem. I had plenty of fuel pressure, but the filter was still dry. When I disconnect the line, the built up air pressure would release so I know I have good fuel pressure. Could the float be stuck in the up position not letting the bowl fill up with any gas?

[Ol Blue K20]

Originally Posted by Gruman

I yanked the carb off and will be going through it soon. I have a rebuild kit on the way.

Heres why:

Well, I tried to get it started again yesterday and still having same problem. I had plenty of fuel pressure, but the filter was still dry. When I disconnect the line, the built up air pressure would release so I know I have good fuel pressure. Could the float be stuck in the up position not letting the bowl fill up with any gas?

Yup...I've seen it more than once. Tap on the carb with a screwdriver handle it should knock it loose

[Gruman]

So I got to tear into the carb, and look what I found...



Seems all is OK here until I look in the bowl...

Sheesh... Glad I decided to rebuild this thing!

[Gruman]

More pics of the carb...

[BLT gmc]

Good choice on the rebuild. Generously flush the entire fuel system. That business in the carb did not originate in the carb. Good luck, Bruce

[Gruman]

I think its the doing of a few generations of mice. Think a flush of the complete fuel system is in order too. How would you do that?

[Gruman]

Well, I did a minimal rebuilt on the carb. (new gaskets, needle, seat, acc pump, check valve, and cleaned everything) Slap it back on and it makes this horrible sucking noise and is spitting gas everywhere! It won't idle and the only way to get it to run is to floor it. Also, when is starts at first, it acts like its WOT for the first few seconds, you'll see this in the video, be sure to watch the throttle cable!!!

Am I missing something huge here? Help me out please!

https://www.youtube.com/watch?v=uRAVBPPnBBk

[Gruman]

After all this I looked in these areas and saw gas... Whats up?
Also, it sounds like the whistling noise is coning from the top of the carb, not the sides.

[Gruman]

Should I give up on it or just spend the money on one of these?

http://www.summitracing.com/parts/jet-35001/overview/

[68C15]

stuck float?
your distributor is off a tooth. It should be about perpendicular with #2 next to the rectangle

[Gruman]

So you're saying my dist should look more like the position this one is in? Photo is just one I grabbed from google image search.




And I think I have figured out why the carb was acting the way it was. I pulled it off the manifold this AM and noticed what I did. I think it should run much better now that the base gasket is NOT OFF BY 180 DEGREES! So I had the primary holes where the secondary holes go and vice versa... So there was this huge gap where it could suck in air on the backside by the secondaries. I feel like such a dumb... well you know. I flopped it around today and just had enough time to bolt it back on and get it connected, but didn't get to try to start it. Ill try to go home at lunch and try it out. Also, don't think the neighbors would appreciate the noise at 7:30 in the morning.


Is there a thread dedicated to these kind of mistakes? I'm on a gun owners forum where there is and its about 30 pages long and has got some funny stories in it. Of course we would have to admit to doing some stupid things to submit to it. I'll give one of mine:

Have a vehicle with a K&N cold air intake and was washing the filter. While I had the hood up, thought I would blow off the dust in the engine compartment. Thinking ahead, I blocked off the clean air intake hole with paper towels to prevent dust from getting in there. Told myself a million times to take them out before the air filter went back on. I think I convinced myself I did take them out and so they didn't get taken out. Well, no signs of anything until 10 miles down the road and I get loss of power and a bunch of lights flashing at me. Wanted to crawl in a hole for a week with that one.

[Gruman]

I had some time during lunch and after I fixed the mounting gasket, the truck fired up just fine and ran like a champ! All that's left to do now is resurrect the braking system. The reservoirs were empty when i bought the truck. I filed the front reservoir with brake fluid and didn't get any stop. Filled the rear reservoir and got a little bit of stop. Obviously I need to do some line bleeding before I go any further.

After I get brakes done, I'll change the oil, change spark plugs, wires, and do a general cleanup of all the shotty wires under the hood. Then start working on getting all the little things like side marker lights, brake lights, and blinkers working.


I figured out (well I still dont know WHAT they are) what these went to. A bunch of dead end wires that went to what I think was the aftermarket compressor for the air conditioning that is no longer there. So I yanked them off and will be taking those off the fenderwell to clean things up a bit.

But the electric choke wire was in with them. I don't think that wire was working the E-choke because it was not hot when the key was on. I guess I'll have to run another keyed-on hot to the E-choke.

[bowcoffin]

Sounds like a stuck float to me... It would make sense if it was on the intake wrong too... I would just a buy a new one personally... you will just have more headaches with it later if it is a float...

[Gruman]

It wasn't the float, It was a bunch of junk in the bowl. That's why I rebuilt it. It runs great now. (once I got the mounting gasket on right!)

I ought to post a video of how much blow by this thing has. The amount of smoke/steam (or whatever it is) that comes out of the valve cover hole is a lot. I don't think there is much life left in this engine.

Should I get a tool for checking cylinder pressure when I change spark plugs next? Or should I be looking for another engine?