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Discussion Starter #1 (Edited)
I am pretty sure I have a problem with the EFI electronics system. The machine has 302.8 hours on it.

The engine starts and runs fine until it is warmed up - approx. 15 mins. After about 15 minutes of run time, the engine looses power, runs rough, fires back thru the throttle body, backfires, and will barely move forward in Low. When it starts running like this, I turn the key off to kill the machine and immediately restart. Upon restart, it will run fine for another 10 to 15 mins then it starts the same problem.

The Diagnostic Blink Codes are showing: 45 - Barometric Pressure Sensor: MAP Circuit Low Input; and 51 - Injector 1 Open Load / Short Circuit to Ground / Short Circuit to Battery. I have tried to clear these codes multiple times by disconnecting the battery and shorting the battery cables together without any luck.


Other diagnostic measures:
A) I have changed the MAP sensor, IAT sensor, and the external fuel filter.
B) The fuel injector was pulled, grommet replaced and injector tested. Resistance is within the tolerances listed in the service manual.
C) Crankshaft position sensor is within the tolerances listed.
D) IAT is within the tolerances listed.
E) Idle Air Control: All pins are within resitance tolerances except the 5-6 measure. It measured out to .2 ohms more than the 31.2 ohms listed.
F) Throttle Position Sensor is within tolerance(without having the harness for testing): 1-2 Closed is 3.847k ohms; 1-2 Open is 781 ohms; 1-3 is 4.835 k ohms.
G) Engine Temp Sensor: 31.8 ohms at about 80 degrees. The manual lists 37.2 to 39.2 ohms @ 68 degrees.
H) I checked wire continuity between every sensor and the ECU. All wires were intact and showed solid continuity.
I) The ignition coil tested within tolerance.
J) I cleaned all of the grounds - battery, cables, engine, & ignition coil. No significant corrosion was found.
K) The battery voltage is at 12.8V.
L) The gas in the tank is fresh.

Other info: In 2008, I had problems with the machine dying. The dealer - Killeen Power Sports - worked on it for about 3 months over the course of about 4 return trips to diagnose and repair the machine. In the end, I brought it home 'fixed.' The dealer put a sticker on the airbox lid that listed: Service Bulletin #24699; Date 3/4/2008; and Dealer Code ATV07-04.


Are there any ideas about what could be wrong with the machine and what I need to do to fix it?

-jse
 

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Discussion Starter #4
I pulled all of the main grounds off at each end, cleaned them, applied dielectric grease, sanded the frame contacts and rebolted. No change to the operating issue.

If it will not clear codes after multiple attempts, does that point to defective ECU?
 

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Josh, you may have a fuel heating problem, which is a much cheaper fix. You may be boiling your fuel. Sounds crazy I know, but as a Polaris Tech, I have seen this before. If you can, attach a flow through fuel gauge and start your machine, let it run and as it warms up check to see if your loosing fuel pressure. Hope this helps.
 

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Run it half full till you have the problem, then fill it up with fresh (cool) fuel and see if it runs better. If so, there was a group that had problems with the fuel pump when hot.

Sean
 
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