Hi, the initial problem was experienced while travelling at around sixty on an extremely cold day, the throttle couldn't be shut off and was revving high. After recovery and replacing cables which seemed the obvious cause, the engine starts ands idles but shuts off when opening throttle (correctly fitted), also revs increased occasionally with no throttle and choke off, I have checked and cleaned the fuel filter, the fuel vacuum tap is allowing fuel to pass, hoses do not appear damaged or trapped, air filter is clean, spark plugs are clean and functioning properly. After reading several forums I'm quite baffled as to the cause. Also there was a humming coming from the fuel pump when the throttle couldn't be closed off. Any suggestions would be great. Thanks.
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If your bike will fire with carb spray, you need a lot more than a simple adjustment. I suspect that you are not getting fuel to the carb. While you have the air filter off, look just inside the mouth of the carb and you'll see a small brass nozzle sticking up. With the engine OFF, twist the throttle grip to wide open throttle position. You should see a stream of fuel squirt into the carb. If not, you don't have any fuel in the carb or the diaphragm in the accelerator pump is bad. Next, pull the fuel line off the carb or the fuel petcock. Crank the engine over and watch the fuel flow from the fuel hose. If it's weak or none, your petcock is bad. In 1996, Harley went to a vacuum operated petcock and they give problems. The diaphragm in the fuel petcock will go bad and you'll have a full tank of fuel but none gets to the carb.
Have you checked to see if you have fuel IN THE CARBURETOR? In 1996, Harley went to a vacuum operated petcock and they've had troubles with them. The diaphragm in the backside of the petcock gets a hole in it and it doesn't allow for a full flow of fuel. Ride the bike with the air filter off until it quits. When it quits, look into the mouth of the carb with the engine not running and crank the throttle grip to wide open throttle. There is a brass nozzle standing just inside the mouth of the carb. When you crank the throttle grip to wide open, you should see a stream of gasoline squirt into the carb. If not, the carb has no fuel in it even though the fuel tank may be full. You'll have to drain the tank and remove the petcock. Take the plate off the backside and take a look at the diaphragm. Gently stretch it while holding it up to the light and check for holes. Personally, I'd replace the petcock with a high quality mechanical petcock and plug the vacuum hose. You'll have to manually turn the fuel on and off old-school style but you won't have anymore petcock problems.
Reserve tube is usually set at a 1 gallon level in the tank, if you only added a gallon to an empty tank,I would fill the tank at least half full, If that doesn't fix the issue then replace the petcock, It's not a carb issue if it runs fine in reserve.
It might not have any fuel, in the carb even with a full tank if it's carburetor equipped. In 1996, Harley introduced a vacuum operated fuel petcock. These things give problems in the fact that they get a hole in the vacuum diaphragm and will not open allowing fuel to flow to the carb. Take your air filter off and WITH THE ENGINE OFF, crank the throttle grip to wide open. When you do this, watch the accelerator pump nozzle, the brass thingy just inside the mouth of the carb, to see if it squirts a shot of fuel into the carb. If it doesn't, you're float bowl is dry.
You can repair the petcock by draining the tank and taking it out. Remove the square plate from the backside. Take note of how the parts are placed in the petcock. Remove the diaphragm and hold it up to the light while gently stretching it while looking for a hole. Personally, I'd rather replace the petcock with a high quality manually operated petcock. You'll have to turn the fuel on and off old school style but you won't have any problems with the petcock anymore. You'll have to plug the vacuum hose as well.
If you just replaced the petcock, you may want to go back and check for a good fuel flow. Pull the fuel line loose from the carb. Hole a catch container under the fuel line and press the start button. The bike should start up and run for a short while or spin over a few times. Either way, watch the fuel flow and see how is coming out of the hose. Does it look like it is enough? If not, check the vacuum line going to the backside of the petcock if you installed an OEM petcock. If you installed a manual aftermarket petcock, did you plug the vacuum hose that went to the backside of the original?
If you have a good fuel flow, you may have gotten some water in your last fuel stop. There may be a screw right on the bottom of the float bowl of the carb. Back this screw out and it will allow the float bowl to drain thorough the hose. Catch it in a catch container and look to see if it's got water in it. If so, buy a can of Sea Foam fuel conditioner and pour some in the fuel tank. This will help get the water out.
If all that fails, you may have trash in the accelerator pump or the slow speed jet. Take the air cleaner cover off the air filter. With the engine OFF, twist the throttle wide open while looking into the carb. You should see a squirt of fuel come out of the brass nozzle in the mouth of the carb. If not, your float bowl is either empty or the accelerator is not working.
Well, you can pull the fuel line off the carb and check the fuel flow there but you'll need a hand operated vacuum pump to open the petcock with unless you have changed the petcock to a manually operated one. Also, when your bike fell over, it could have stirred the sediments in the bottom of the tank up enough to clog the fuel screen in the tank. Take your petcock out to check for this. To get the fuel out of the tank, loosen the petcock until the fuel will run out around it and catch it with a fuel directing it into an empty fuel can.
you need to have your throttle position sensor checked. tps its starts goi9n bad and get erratic readings to the computer. i just experienced some what the same problem, come to stop sign, let off gas pedal it dies. i set up the idle a lil bit and solved the prob and then had tps checked. replaced it and solved the prob. not 100% that that is the prob but that is what i experienced.
Might have a restriction in the fuel filter, fuel petcock could have a restriction in it. Remove fuel line from petcock to fuel filter, move fuel vale to prime, fuel should flow freely. If not will need to clean fuel tank and petcock. If flows smoothly go to the outlet side of the fuel filter, same time should happen if not them restriction is in fuel filter, replace filter. Lastly could be restriction going into the carbs, in this case carns will need to be removed and cleaned. Good Luck
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