Bike stutters under boost

[mysticblu999]

Hey guys i got a problem, my bike studders under boost.Off boost it does fine. Today i went through second, it ran fine, but then i hit third and it would studder and wouldn't pull at all. I have been running leaded fuel for the last 2 tanks and it has started (i think) when i first started running it again. I first thought it was my plugs have not checked yet. Or does this sound like a FMU problem. Any help?

 

[cdhoroho]

more info like what did the FP look like under boost and what afr was it tuned for (ie what fuel tuned for also)

yes it could be plugs
also maybe a little too rich
but also could be lean under boost
if the fmu has gone bad this will happen

 

[kawiboy11]

not a good thing , hope it's not lean or the fmu failing. What king of FMU do you run?

 

[mysticblu999]

fuel presure.. i have no way of checking it or the knowledge to do so, except for seeing it done once. i would be doing good to change the plugs lol

AFR i have no idea but i can email some one my map if that helps

The FMU is a BEGI i think, its silver and its the one that comes with the RCC stage one.

I had to take the header off once to tap one of the holes for the bolts. when i did it layed on the ground for the weekend and the inlet (?) where the air filter goes filled up with oil. I thought i got it all out. i put the header back on with out the charge pipe and blew alot out then i wipe it out the best i could. It ran fine for a while until i put the sonoco 110 in it. Maybe lead deposits on the plugs? But it runs fine off boost

one other thing, strange enough... the bike has never idled well off the choke, now it idles fine off the choke? could that be related?

thanks for all your help

 

[mysticblu999]

i also thought about running all the 110 out then putting pump fuel back in. It was tuned with mostly pump and a gallon of c16

 

[suzuki4life]

pump the 110 out...swap the plugs if necessary...

I am betting you got some backfires with severe stuttering....

either it was wayyy rich and was loading up....

or you backfired and blew the up pipe off

or....


you blew a head gasket (hopefully that is all if it gets to this point...should be some pressure in your overflow tank if it did.)

 

[dadofthree]

Good luck on the fix

 

[boosted]

sonoco 110 and vp c16 runs richer than pump.

 

[mysticblu999]

you guys are gonna kill me...

I had 2 pinched fuel lines...

I straightened them out and now it stopped.

maybe it was a good thing i had the race gas in there?

phew... i hope thats all it waslease:

 

[suzuki4life]

you guys are gonna kill me...

I had 2 pinched fuel lines...

I straightened them out and now it stopped.

maybe it was a good thing i had the race gas in there?

phew... i hope thats all it waslease:

then there was more to the story than you told us...pinched lines don't "just happen" on their own.

 

[Ripcord4]

I would advise putting a fuel pressure gauge on the bike. With pinched fuel lines you would have seen that the pressure was really high, at least if the return line was pinched

 

[suzuki4life]

I would advise putting a fuel pressure gauge on the bike. With pinched fuel lines you would have seen that the pressure was really high, at least if the return line was pinched

most of the time if the line pinches or collapses....the pressure drops.

If your lines because old and they bubble...your pressure drops.

 

[kawiboy11]

Good to hear, better then a bad FMU! ???

 

[Youkai]

I thought it was pinched lines, same thing happened to me. Invest in some steel braided lines, that's a future purchase.

 

[mysticblu999]

I thought it was pinched lines, same thing happened to me. Invest in some steel braided lines, that's a future purchase.

Where were you planning on getting yours at? sounds like a good idea to me. On my bike the line that went to the FMU was really too long and it was just in a bad position.

The bike is great but it has made me learn to work on it. Oh well thats just part of it I guess,

 

[MET]

You did the right thing, always check for the little things first.

 

[suzuki4life]

okay...please explain how braided lines will keep them from being pinched.

 

[cdhoroho]

braided lines arent a good idea on a bike (unless coated with rubber)
due to there abrasiveness they will cut through wires and the coatings and cause major electrical issues

i run parker or earls lines and they are very durable and dont kink when routed properly