Well, here we go again. I swapped plug wires with a friend,no change.Now when its running i see bubbles in the gas tank which increase if you rev it up.Could it be that the timing is out? , and if so how do you check it. I appreciate any info. Thanks.

If the timing is off, there's a problem with the ECU. The ECU controls all timing functions. I can't explain the bubbles.

Gasoline must be boiling. Taking the cap off would reduce the pressure in the tank, making it easier for the gasoline to do this.

Very !!

quote:

Gasoline must be boiling. Taking the cap off would reduce the pressure in the tank, making it easier for the gasoline to do this.

These tanks are vented to atmosphere so there shouldn't be any pressure to begin with. The bubbles could be explained by a number of reasons, I doubt boiling is one. If the gas is boiling you have some serious issue's.

The tank vent hose that runs up to the pod might be pinched. That could explain the bubbles and restricted air might cause fuel starvation at WOT.

You should be able to see the vent line between the tank and the pod. On every Polaris I've seen in hot weather when the machine is hot, you can see gasoline bubbling in that line. If it doesn;t on yours, then I would trace the line and look for a blockage.

This message has been edited. Last edited by: YnotAZ,

If the vent hose gets plugged completely, it will just die and not run...been there done that. Opened up the tank and had major pressure built up. My vent tube got pinched when I put my guages in the pod. The machine ran great for about 5-10 minutes and then killed. I always have bubbles going out the vent tube. Every polaris I have seen does this.

The vent tube is fine,and when i saw the bubbles inthe gas in the tank it was cold,like ran for 5 mins.Also when i rev it up with the tank almost full, gas actually squirts out the top when the caps off.Very strange.

sounds more like a fuel pump issue.

quote:

Originally posted by Heller1 - Ron:
If the vent hose gets plugged completely, it will just die and not run...been there done that. Opened up the tank and had major pressure built up. My vent tube got pinched when I put my guages in the pod. The machine ran great for about 5-10 minutes and then killed. I always have bubbles going out the vent tube. Every polaris I have seen does this.

actually if you plug the vent, u didn't have a pressure issue, you had a vacuum issue

Don't the Yami's have problems with boiling gas...

I agree with Heller-Ron.\,
The Yamis have a lot of problems, one of them being boiling gas under pressure.

Elk is right about vacuum.

With a metal tank, on a vehicle, I've seen them "implode" when not vented properly. Since ours our plastic, I'm not sure but they very well might kill the motor before damaging the tank.

Like I said in your 1st post:

You just need to have someone look at it that knows what they are doing. EFI is new to the atv world and the guys are not very good at diagnosis yet. Its probably just a sensor.

one thing you guys haven't talked about is that the fuel pressure regulator is in the tank and the fuel pump, pumps more than the system needs. so the regulator sends the gas back. thats probably the bubbles you are seeing.
What is it doing?