Engine won't run unless primer bulb is being pumped
At idle it runs fine but once the throttle is advanced it runs for about less than a minute it starts spitten then dies unless the someone is pumping the primer bulb. when someone is pumping the primer bulb while running it is fine upon advancing throttle.
Re: engine won't run unless primer bulb is being pumped
I have the same problem and may have a solution. I looked at the primer pump and it was cracked letting air into the system. When I pumped it my finger was over the crack and it worked fine. When I stopped the crack was able to **** air again. Take a look.
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Does the engine run fine after it starts? Most common problem with primer bulb losing prime is an air leak in the fuel line or primer bulb. Air leaks don't always leak fuel. If there is an air leak between the primer bulb and gas tank there is no pressure, only vacuum. If it is not a major leak it might not leak without pressure but it will allow air to enter the fuel line. If it is a very minor air leak it could allow air to replace the liquid in the fuel line over time, but so little air once it is primer again that the fuel pump can over come it with volume of fuel.
Primer bulbs do not stay firm, as they are when initially pumped up, after the engine is running. There are check valves in the primer bulb that hold pressure in the primer bulb and throughout the fuel line to the engine. Once the engine starts the fuel pump creates vacuum drawing fuel into the engine diminishing this pressure and releasing the check valves. At this point the primer bulb is just another segment of fuel hose allowing fuel to pass through it as the fuel pump demands. The primer bulb functions much better when the outlet side is higher than the inlet side. This position makes it easier for the check valves in the primer bulb to seat and release as needed. If the primer bulb is functioning properly and is positioned with the outlet side higher than the inlet it should not be necessary to cover the end of the fuel hose with your thumb to get it to prime.
If the engine is hard to start after being fully primed there could be a problem with the fuel system on the engine. Some engines are hard to prime once air has entered the system, especially fuel injected models.
If you mean your having to pump the primer bulb to keep it running. Then the main jet is plugged. 1. Take jet(bowl nut) off the bottom of the carb 2. spray carb cleaner through all holes. (up to 4) 3. find a hemming pin and break of the sharp tip, run that through all small holes there may be one hidden in the threads. 4. repeat step 2. and dry with a shot of air( air dusting cans are ok). These steps are for emissionized carbs( no mixture screws )
It should start easily, start with fresh fuel/oil, pump the primer as many times as it takes to 3/4 fill the bulb, pull the choke fully out, crank the engine until it fires once, push the choke fully in and crank again until it fires up, after re fueling a warm engine, pump the primer again until it 3/4 fills the bulb,before cranking the engine pull the choke fully out and in again( this will engage the part throttle ) then crank the engine until it fires up.
The choke system is connected to the half throttle position, if you lift the throttle trigger the choke pull will automatically return, whilst trying to start do not lift the throttle trigger, the starting procedure is, pump the primer bulb as many times as it takes to 3/4 fill the bulb, pull the choke pull fully out, this will switch the saw on and engage the half throttle, crank the engine until it fires once, do not continue to pull,it will actually not run on full choke, if you do continue to crank with the choke fully out, you will very quickly flood the engine, now push the choke fully in, now crank the engine until it fires up, lift the throttle trigger once, this will dissengage the half throttle, and it should now come down to idle.
Make sure you have fresh fuel mix in the tank. Pump the primer bulb about 6 times or less until the bulb draws fuel into it. This fills the carburetor with fuel. Close the choke and set the fast idle if the throttle trigger has a button near it--otherwise, operating the choke auto-sets the fast idle. Don't operate the throttle again until the engine is running. Turn on the ignition switch and pull the engine through smartly. It should start within several pulls. If nothing happens, then get back to us for some troubleshooting help. Hope this gets it running!
The H is for high rpm (Main mixture) and the L is for Low rpm (Idle Mixture). First turn in both screws all the way in and then turn them both out 1 and a half turns. Pump the primer bulb if the equipment has one. Start the engine, once it is idling, turn the L (Idle Mixture) screw out (counterclockwise) from the preliminary setting until the engine speed decreases (rich). Note the position of the needle. Now turn the adjusting needle in (clockwise). The engine speed may increase, then it will decrease as the needle is turned in (lean). Note the position of the needle. Set the adjusting needle midway between the rich and lean settings as in the picture below. Don't touch the throttle during this procedure. Once you have found the best idle speed for the engine then you need to adjust the high rpm. This process is the same as with the idle rpm process but you need the to hold the throttle wide open while you are adjusting the H (Main Mixture) needle on the carburetor.