Tnytro wont start when hot

[1madbird]

So I have had a turbo on my nytro for 3 years now and never had a problem until last year I put a fuel pressure gauge on just to see what it was doing and at Idle it was at around 50 PSI so I put it down to around 40 and then it would take a few cranks to start. Then this year I was running it in the garage and when it got hot It would not start, then after it cooled down it would fire right up. Put new plugs and rode it and still the same problem any one got any ideas. My fuel pressure is around 45 when cranking

 

[brutis]

Are you running an aftermarket fuel pump or stock in tank pump ?
If you are running an aftermarket pump it might be the pump location.
We ran into some issues with a powderlites turbo kit.
The pump was mounted beside the rad and when the sled was shut off after
running awhile the fuel inside the pump would boil causing the pump to
air lock.We would have to bleed the pump and then it would start again.
We have since moved the pump away from any hot engine parts and now
their are no issues.

 

[SylvanLaker]

too rich?

 

[1madbird]

Thanks for the input guys. Brutis I think you are right about the air lock but I dont think it is my fuel pump and it is not rich because there is no fuel smell or smoke coming out of the pipe. I have a friend who races bullet bikes and he also sell race fuel and he said he has seen it at the track when the bikes will vapor lock right above the injector and wont let any fuel to the injectors. He said it is usually due to bad fuel that causes it to boil to soon. So I am going to try some new fresh fuel and see what it does.

 

[1madbird]

Well I thought I would be able to Just top off my fuel and it would clean out the old fuel but it still wont start so now I guess I will have to drain it completly and try that.

 

[jehay]

100% sure its your fuel is getting so hot its boiling and vapor locking been there! Best thing to do is install all the vents it the plastics to get the heat out worked on mine!

 

[julio]

100% sure its your fuel is getting so hot its boiling and vapor locking been there! Best thing to do is install all the vents it the plastics to get the heat out worked on mine!

I had the same kinda prob with a mcx apex, fuel pump vapor locked, opened the line and ran the pump till the pump ran gas and it worked afterward. done this twice so far. one time it would not start the next it would start but not run full tilt, vapor in the fuel lines.. julio

 

[1madbird]

I will put as many vents on as possible it just seems weird that I never had any issues until this year I was woundering If I had some bad injectors or something.

 

[1madbird]

Ok guys I need some help I have found that the fuel is not the issue. I can run it in the garage for about 10 minutes with all the covers off and it still wont start until it cools down. I have felt the fuel rail and it is still cold. I believe the problem is with the ISC valve. It gets really hot and when I omh it out it is out of spec. Can some tell me what this valve does looks like it just controls air to each throttle valve.

 

[1madbird]

Ok I am still having problems. I have checked the fuel rail when it wont start in the Garage and they are still fairly cold. I have also found that when I am pointing down hill it will start. I think it has to have something with the injectors but not sure.

 

[rknight111]

Are you running a MSD fuel pump? I had issues with the power going to the pump on mine. For the first year it was fine and then once the sled got warm the power supply to the pump went waco. Changed the Relay and the same. So I ran a separate relay off the ignition and the problem was fixed. I thought I had a clogged filter, or a bad pickup, then found out I didn't, changed the fuel pump and the same, so I ran jumper cables to the fuel pump and my problem was resolved so I wired it. Check your fuel pump.

 

[1madbird]

I am not running the MSD pump but another brand and I know the pump is coming on because I have fuel pressue gauge and so there is no problem with that. I have read on TY that some guys are having problems with vapor lock in the fuel rail. and so they have some sort of bypass that will allow the fuel to bypass the regulator and go back to the tank to get rid of the air. I was thinking this could be the problem but my pump will produce 120 psi and it is regulated to 40 so I should already be sending fuel and any air back to the tank but i am going to check that this week.