MCX 270 not running past half throttle

[Sleds R Fun]

Approximately 30miles into 70 mile ride sled started farting and popping past half throttle! Stopped for 10 minutes and started sled, it decided to run for about 5 minutes but then back to farting and popping.
The Nitro has 5000 miles and this is the first motor/electrical/injector hiccup??I now have heat on sled hoping its as simple as moisture.
Any suggestions where I should start checking?
Thanks

 

[Northernboy]

First thing I would check would be if the MCX box and injectors are working. This simply can be done by pressuring the MCX box at idle a few pounds. If they are working then the engine will load up. If they are not working I would check the connections for the MCX box. Then I would check fuel pressure at idle. Also check your TPS in diagnostics. Could also be a blocked boost line.

Good Luck.

 

[Sleds R Fun]

MCX box

Pulled hose line from box and sled loads up as you said. To the point it won't run!
Will get TPS checked next!

 

[Sleds R Fun]

TPS

How do I get into diagnostics and what is the range?

 

[Northernboy]

When you disconnect the line from the MCX box you will have to pinch it or the Stock MAP sensor will not see vacuum and stall. With the line disconnect and pinched it will idle normal, then put another line on the MCX box and pressurize it. Engine should load up. Not sure if you did it this way or not but this will tell you the MCX box and injectors are working.
To check the TPS there is a procedure in the service manual. If you can't find it I can email you the section to check it.

 

[sledheadd]

Approximately 30miles into 70 mile ride sled started farting and popping past half throttle! Stopped for 10 minutes and started sled, it decided to run for about 5 minutes but then back to farting and popping.
The Nitro has 5000 miles and this is the first motor/electrical/injector hiccup??I now have heat on sled hoping its as simple as moisture.
Any suggestions where I should start checking?
Thanks

Check your header and bellows for cracks .
If its as bad as you described I'm betting your bellows are finished.

 

[Sleds R Fun]

MCX Box

Pinched off proper line. Pressured up MCX box by blowing in it! No engine loading or change in RPM. Northrnboy, you think it's the box? Will check TPS tomorrow!

 

[Northernboy]

It could be the MCX box but I would suspect it to be a wiring or connection problem. I would check your connectors for the MCX box, clean connectors and put dielectric grease in them. You can always try another MCX box if you know someone who has one.

 

[Tuesday]

Could be a boost/exhaust/vacuum leak, mcx box or recently I had this issue. Check charge tube, intercooler, bov, check vacuum lines or ice/cracks, hold had on exhaust see if sled will stall if not then prob a header leak.

Did this problem come on slowly or just all of sudden?

http://www.snowestonline.com/forum/showthread.php?t=343281

Wire had rubbed through could not build boost.

 

[Sleds R Fun]

MCX box

Pinched proper line and pressured box to 15#'s and motor loaded then died, did test a few times so hopefully a good indicator box is working.
Checked diag and no codes.
Anyone ever have problem with throttle block?
Machine builds boost , just farts and pops in process.

 

[dexter]

Did you change your plugs. Sometimes it's the simple things. Saw a couple of sleds that did exactly this and it was the plugs

 

[precision-weld]

Dont know if its worth checking. But my apex did that same thing twice. Both times it was the fuel pump. Is your pump making more noise then usual when you turn the key on?
Hope you get it figured out!!

 

[Turbo X]

Is the sled for sure running rich or is it really running lean????

 

[BigFish BC]

one or more of your secondary injectors could be going & spaying to much fuel,thats about where the secondary injectors start to come on.

 

[sledheadd]

Have you checked your exhaust for leaks?
It's easy to do and would eliminate one more thing if the exhaust is all good.

Mine did the same thing.

 

[Sleds R Fun]

Improper running

New plugs installed, header not cracked. Testing in the morning. The pump is making more noise than norm I think.
Will report back after testing.
Thanks for all te imput.

 

[JDen]

For what its worth, we had a few of our groups sleds start doing what sounds very similar last year. Turned out it was the inline fuel filter on all of them. I change mine before every trip now just because they are dirt cheap and then I know if I have any issues it isn't that. Might be worth changing.

 

[BigFish BC]

For what its worth, we had a few of our groups sleds start doing what sounds very similar last year. Turned out it was the inline fuel filter on all of them. I change mine before every trip now just because they are dirt cheap and then I know if I have any issues it isn't that. Might be worth changing.

yah i had mine do that at yamafest last year almost forgot it was same thing die at half throttle

 

[Sleds R Fun]

Figured for now, thanks JDEN

New plug and fuel filter. Believe it was filter. Ran sled for 5 minutes and ran great. Headed out with sled neck crew in morning so guess I will really know for sure after tomorrow.

 

[powder pig]

having same problem woundering how you made out on weekend, if it worked or not, what mcx box you have