Stuck float valve or stale gas?

[jseabolt]

1976 Chevy 454 big block with a Quadrajet. Or Quadrajunk as people refer to it as.

 

Spring of 2012, I get the truck running which had been sitting for awhile. Dad loads it up with mulch, get's it home then calls me and says the truck won't start in the yard. So I pull the tubing off the carb and the fuelpump is pumping fuel to the carb, just not past the fuel bowl so I assume the float valve has stuck closed.

 

So I take the top of the carb off and only to open up a can of worms (metering rods) unlike anything I've ever dealt with. Sure enough the fuel bowl was dry as a bone.

 

I broke the gasket between both halves and would have to buy a whole rebuild kit just to get the gasket. I tried making one off the old one but due to the metering rods, now when the secondary opens, stalls out under WOT because the metering rods are touching my homemade gasket. Ait but no fuel.

 

I finally decide to take the carb to a guy with a lot of experience with Quads. He rebuilds it and it has started and ran ever since until here recently.

 

So the truck was filled up with fuel probably back in May of 2012. It ran back in the fall when was parked outside until now.

 

Now the truck will start and run with ether but not on it's own. At one point It did idle for about 10 seconds but that was the longest.

 

I suspect the float valve has either stuck or the fuel has become stale. I just recently dealt with this same issue on his 58 Ford 800 tractor. The float valve on that thing stuck closed after it sat over the winter.

 

So does that sound logical? if a vehicle sits for 6 months and the fuel evaporates out of the fuel bowl, it leaves residue behind and that is what's sticking the float valve?

 

So what is the best way to break it loose and clean it without having to pull and tear the carb apart again?

 

Remove the fuel filter and get one of those rubber vacuum plugs, poke a hole in it the end of the cap, stick it in where the fuel filter screws into the carb (or over top of it) and using an air blow off tool stick that into the inside of the vacuum cap (or thought the poked hole) to create a seal. Then apply air pressure.

 

Question is how much air pressure? I'm afraid something like 80 PSI might damage something or mess the adjustment up on the float. I need just enough air pressure to blow the needle off the seat. Maybe 15 lbs?

 

Then perhaps spray some carb cleaner into the hole and allow it to sit.

 

I got lucky one time on an old lawnmower engine. It sat for about 5 years and it smoked and backfired. I drained all the fuel out of the fuel bowl, connected a hose to the carb and poured the carb full of straight fuel injection cleaner. Then let it sit for about 30 minutes, drained the fuel bowl and refilled with fresh fuel and it worked!

 

Any chance I could get lucky using the same method with this Quad?

 

Concerning my stale fuel theory."They" say gas will go back in 6 months. Any chance this gas being 16 months old has went bad to the point it won't allow the engine ro run? I've ran engines before with 2 year old gas. They will usually knock on old gas (even with an 8:1 C/R) but run fine otherwise. If the gas is four years old, then the engine runs really rough but it will start and idle.

 

 

 

[txab]

You need to add fuel stabilizer to the fuel, especially since it's now ethanol. Within 6 mos I notice performance differences on carbed engines. I never leave fuel in fuel bowls/carbs on small engine equipment or boat motors.

 

 

I've never had the problem with any of my QJs that you describe

[gmtech4]

take it off and apart , no pissin around

[jseabolt]

You need to add fuel stabilizer to the fuel, especially since it's now ethanol. Within 6 mos I notice performance differences on carbed engines. I never leave fuel in fuel bowls/carbs on small engine equipment or boat motors.

 

 

I've never had the problem with any of my QJs that you describe

 

I've been using that Stabil Marine ethanol treatment in all my vehicles and lawn equiptment. Wheather it actually does anything or not I guess it can't hurt. But would that prevent the float valve from sticking when the fuel evaporates out of the fuel bowl? What could be done for that in the case of long term storage?

 

I fired up my 68 Ford Fairlane yesterday and drove it to work today and it runs just fine. I filled it up with non-ethanol gas last September but added Stab-il to it. Although I have started it every now and then since then. Well the last time I fired it up was back in the spring because I was thinking about selling it and was showing it to a guy who was interested in it.

 

The trouble with Dad is he let's his stuff like his tractor and truck sit out in the weather and doesn't start it at least every three months or so then when it goes to pot, he want's me to fix it. He did park his tractor in the barn over last winter but the float valve still stuck shut on it.

[Duelin]

Loosen the gas line and remove it from the carb. Then take the fuel filter out and inspect it. While you have it out take some carb spray with a nozzle extension and spray it inside. Try to trap enough carb cleaner inside so it can soak the needle and seat. I have an old piece of fuel line that has a 90° bend and about 4" long. I point it straight up and fill it with carb cleaner and let it sit. Also you can take a small hammer and tap on top of the carb. Use common sense when tapping with the hammer. Don't hit it hard enough to break anything. Some times you can free up the needle that way.