Truck Only Starts When I Pour Fuel Down The Carb

Posted in Fuel Systems & Components

I’m going to try to be detailed on this, I had a 2.5l fuel injected engine in my s10, it didn’t run so I swapped it out for a 305. I put airbags on it and when I did, I had to get a fuel cell because the stock gas tank didn’t clear. It was running just fine out of a gas can that I had the pick up and return hoses ran into. So once I got my fuel cell I put in the back of the truck but I wasn’t getting fuel anymore so I then tried running out back out of the gas can which didn’t work either so I decided that it must be my mechanical fuel pump, so I replaced it, hooked everything back up to cell and it fired up and was getting sufficient gas. That was all on Saturday and Sunday now I’m not getting anything again after flooding the engine on monday. A friend flooded it trying to start it because I have a Holley 650 spread bore, double pumper and when you push the accelerator it sprays some fuel! Anyway, after he flooded it he kept trying to start it so he poured some gas down the carburetor, and everytime he tried starting it he pumped the gas. So, after holding the pedal to the floor and cranking it, and taking out all the plugs and cranking it, then replacing the plugs, it still will not start! If I pour gas down the carb, it will run until that gas runs out, everytime it starts it sort of shakes and its smoking black out of the pipes. It still isn’t getting gas from the gas can or fuel cell even after a new mechanical fuel pump. I know this has been long and thank you for enduring. And advice at all?
the engine did have an electric pump in the tank but is also set up for a mechanical pump on the block and sorry I failed to mention that I had cleaned it out with injector cleaner.
As much money as I have spent on that carburetor I don’t believe I will be changing it anytime soon. I do have hedman headers, a cam, an aluminum intake, and its been bored over.

There are 4 Answers for "Truck Only Starts When I Pour Fuel Down The Carb"

    1. Mr. Hypothetical says:

      Plugged ventrilo, clean it

    2. Mad Jack says:

      I know this may sound stupid but maybe the engine is setup for an electric fuel pump. There may not be anything coming off of the camshaft to move your lever on the mechanical fuel pump. If this is the case, you may want to replace your mechanical fuel pump with an electric one.

      It also sounds like you have this engine flooded very badly. Remove the spark plugs again and attempt to clear the engine.

      Use some starting fluid instead of dumping a bunch of fuel down the carburetor.

      Also, with all of the fuel you dumped into this engine, you should change the oil as by now it is most likely contaminated with fuel. If you don’t, you risk damaging your new engine.

      Also, some advice on your carburetor selection. This one is too large for your application and may actually hurt your performance. The double pumper carb may also part of your problem because it is feeding your engine more fuel than it can handle. You may have frequent problems with flooding this engine with this carburetor.

      If your 305 had the largest possible valves, perfect cylinder head ports, perfect intake maifold, perfect camshaft, perfect exhaust, it could only take in about 530 CFM of air at 6000 RPM. To move 650 CFM of air you would have to spin this little 305 up to 7400 RPM. I seriously doubt you will ever do this on the street. Most people don’t take their street small block Chevy’s mich over 6000 RPM. Also consider that these are the maximum amounts under prefect conditions. Your engine almost certainly flows less because you more than likely don’t have the perfect components I listed earlier. It more than likely flows at least 20% less. A better choice for this engine would be the Holley Street Avenger 4150 rated at 570 CFM. It will run better and make more power with this carburetor.

    3. Donkeyeyes says:

      Did you try fuel injector cleaner. Plugged orifices?

    4. Jeffbudda73 says:

      Try messing with fuel pump