2001 ZR800 Hard Starting

[hunt23fish]

If it sits for more than a few hours it takes at least 40 pulls to start. Is there a check valve in a fuel line somewhere? Carbs are clean and it runs perfect once it is running and you get your breath back. Plugs are dry after 30 pulls so it is lacking fuel not flooded. Ideas?

 

[jimfsr]

Sounds like the carbs are draining for some reason. All the pulls are to pump fuel back to the carbs. Next time, shoot a little fuel or starter fluid down the plug holes and see if it fires off and runs, or if it fires and dies out again. if it dies out after a few seconds, there is not enough fuel in the carbs for some reason. If you cant figure it out, a primer kit might help. There are several possibilities here. Good luck...

 

[hunt23fish]

I have poured fuel in the plug holes and it does fire off and run. It takes two times of dumping fuel in the cylinders to make it continue running.

 

[jimfsr]

either the fuel pump is bleading down and has to be primed back up with all the pulls, or the float bowls are leaking all the fuel out. Not likely to leak all the fuel from both carbs at the same time. It almost seems like the fuel pump is siphoning all the fuel out of the carbs, but it is not possible if the vent tubes are open and the fuel tank vents are open also. If the tank vents are plugged, the motor wouln't run long, few miles maybe, and the tank would litterally implode from the vacuume created in it. upon removing the cap it would woosh as the air went back in. Odd that both plugs would be dry after a fews pulls, not just one. It seems to suggest a common problem for both cyl. Try some things and let us know....

 

[bouncer]

Stupid question but are you are using the choke leaving the throttle at idle position? Lifting the throttle bypasses the choke circuit.

Other then that I would look at the fuel pump like Jim mentioned. Pull it apart and check the diaphragms for tears or wrinkling/shrinkage. Good luck

 

[G]

Can you smell raw gas? Check all the gas lines. This is an old enough sled that if the lines have not been replaced it is surely time to replace them. Better yet - take off the airbox. Get a tank of compressed air. Take off the gas cap and pressurize the tank with the compressed air. Have a buddy move all the gas lines around to check for leaks while you are pressurizing the gas tank. ( One hand on air squirter, one hand on rag in tank top.) This exact same thing happened to a T-Cat of my buddy's. One day it backfired on start-up and ignited the raw gas. End of T-Cat. ps - snow does not work to put out a gas fire.

 

[jimfsr]

Just for clarification, the enricher (choke) if open, is always adding un-metered fuel, throttle open or not. Although the signal to it is not as strong, (with the throttle open) It is common on the older sleds to have the plunger stick in the open position, resulting in a rich condition at all times, but more so at idle to 1/4 throttle, where the engine can't burn the extra fuel.

 

[bouncer]

Just for clarification, the enricher (choke) if open, is always adding un-metered fuel, throttle open or not. Although the signal to it is not as strong, (with the throttle open) It is common on the older sleds to have the plunger stick in the open position, resulting in a rich condition at all times, but more so at idle to 1/4 throttle, where the engine can't burn the extra fuel.

Just for clarification it is also common on the older sleds to have the enricher plunger
stick closed in the bore which could also be another reason for the hard starting.

Air will always follow the path of least resistance. Lifting the throttle while trying to
start the engine allows air to flow past the throttle plate/slide. This small amount of air,
without the engine running does not create enough vacuum or flow to do anything else once the throttle is opened except follow the least resisted path. Thus bypassing the enrichment circuit. This is why even with the enricher on you can hold the throttle open and clear a gas flooded engine.

 

[shawnl]

zr800

you have a bad fuel pump