help,rx1 w alpine turbo, started backfiring - sputtering

[925rotax]

sled ran great all day except at the end. sled started backfirring and sputerring real bad,like it was running on 2 or 3 cylinders, tried choking it and did not help, shut it off for 10 -20 min and runs good for a few mins and starts again . 04 rx1 w front mount alpine ,g28rs, corrillo rods ,je pistons,heavy springs, running 18 pounds boost today, any ideas would be appreciated, taking it into the shop tommorrow,check compression,fuel pressure, almost seems electrical? half a tank of c12 in it

 

[lakercr]

sled ran great all day except at the end. sled started backfirring and sputerring real bad,like it was running on 2 or 3 cylinders, tried choking it and did not help, shut it off for 10 -20 min and runs good for a few mins and starts again . 04 rx1 w front mount alpine ,g28rs, corrillo rods ,je pistons,heavy springs, running 18 pounds boost today, any ideas would be appreciated, taking it into the shop tommorrow,check compression,fuel pressure, almost seems electrical? half a tank of c12 in it

Start with the simple stuff - did you check to see if your intercooler has blown off the boots?

 

[4strokes are better than2]

check your header for cracks,check all your electrical plugs up front in the nose for moister .

 

[Ted Jannetty]

sled ran great all day except at the end. sled started backfirring and sputerring real bad,like it was running on 2 or 3 cylinders, tried choking it and did not help, shut it off for 10 -20 min and runs good for a few mins and starts again . 04 rx1 w front mount alpine ,g28rs, corrillo rods ,je pistons,heavy springs, running 18 pounds boost today, any ideas would be appreciated, taking it into the shop tommorrow,check compression,fuel pressure, almost seems electrical? half a tank of c12 in it

Water in the coils or Plug holes?

 

[KnappAttack]

Check the wiring up in the nose of the sled where it runs thru the bulkhead, right under the toolbox. I've seen wiring wear thru rubbing on chassis and cause this even on stockers.

 

[925rotax]

ill be pulling it in the shop tonight after work, really appreciate all the info on where to start,ill let you know what i find, thanks again everyone!

 

[RX1T]

Mine did exactly the same as your sled last winter, i cleaned the carbs and the problem was solved.

 

[925rotax]

well? checked the updated alpine header=no cracks, checked all boost connections and did a leak down= no loss,checked wirring through the bulkhead and no visible cuts,changed out the plugs and installed irridium ngk, plugs showed no variance between each other, started it up and ran it throughout the throttle for about 10 min,no backfirring,sputtering or running sluggish. maybe it was moisture somewhere, anyways ill try it out again this weekend, fingers crossed, thanks everyone

 

[Ted Jannetty]

well? checked the updated alpine header=no cracks, checked all boost connections and did a leak down= no loss,checked wirring through the bulkhead and no visible cuts,changed out the plugs and installed irridium ngk, plugs showed no variance between each other, started it up and ran it throughout the throttle for about 10 min,no backfirring,sputtering or running sluggish. maybe it was moisture somewhere, anyways ill try it out again this weekend, fingers crossed, thanks everyone

Spray Silicone and Dielectric grease helps a bunch against moisture.

 

[925rotax]

thanks again ted and everyone above ^^

 

[925rotax]

well, i thought i had the problem solved, took it out today and 5 mins into ride the sled started popping ,sputtering again, sounds like its running on 3 or 2 cylinders ,turned the choke on and it ran a bit better? a/f reads way lean when problem occurs,problem is intermittent, i changed out plugs and used dialetric grease on all connections, boots,intercooler is on tight and boots, sled sleeps in a heated garage but maybe not for much longer woundering if the fuel pump is going or fuel regulater, anyone know what pressure should be, ill put a fuel press reg on it and check wiring in the nose again, thanks

 

[new24stroke2]

Mine did the same thing it was the header.The way I found out was wathcing the fuel pressure gauge.It should run about 4.5-5 psi when running.When you get in to boost it should boost pressure plus you 5 psi.So at 10 pounds boost you should read 15 psi fuel pressure.When my header cracked I could only get 8 psi fuel pressure and it would miss and back fire bad.

 

[925rotax]

I checked the header last time , removed tank etc,and no cracks,i have the updated alpine header and downpipe.I will check the fuel pressure next. when the problem cuts in i cant even bring rpms up to build boost, thanks

 

[925rotax]

any suggestions?

i connected a fuel pressure gauge and at idle 5-6 pounds of pressure,warmed sled up and could not get it to act up,seems to act up under load when at operating temp, very intermittent, ill have to drive up to the snow line this weekend to try it under load. i checked the header for cracks again andall good.turbo flange to header flange tight,dont think its moisture, sled is in a heating garage and is dry,acted up last time within 5 minuets on the snow, after sitting warm in a garage for a week plus,intercooler is tight and carb boots,really wondering if its a the fuel pump? looked at electrical while the intercooler was off and no rubbing. im not sure where the fuel filter is located? is it in the tank? do thecoils fail completly or intermitly, really lost on this one? when it suddenly acts up the rpms drop,pops,sputters backfires cant bring rpms back up off idle,air fuel reads way lean. if i shut it down and sits for 10 mins it will start up and run fine for 2 -3 min and problem usually comes back, sometimes in 10 min intermittent, thanks!

 

[new24stroke2]

Check your tors.My uncles sled acted like it was dropping cylinders.By pass it and see what happens or get a manual and do a recistance test