I read that post.. why dont you post links so the threads can be researched together... You know that one here and this one there...Just an idea.
You're Right! Here goes.
Good evening all,
I've written several threads about my saga this summer with my 2006 Sportsman 700 EFI. Since they are all over the place, someone smarter than me suggested I link to the other threads as they contain some useful information. My intent is to post any further updates to my saga in this thread. Replies that pop up in the others will be answered with a link to this one. Here are the links and if you are new to the story, a long update.
Desperate pleas for help and some additional problem areas to look at.
Hopefully zeroing in on the problem.
Could it be the fuel regulator?
To bring it up to date this is mostly a copy of my post in another forum:
I apologize for the REALLY long post but Iíve been trying to fix this all summer long and there is a lot to tell. Please realize that Iíve searched dozens of forums, read thousands of posts, and taken about 20 pages of notes. Lots of people have the same problem as my machine does but there seems to be no answer.
My real question is whether anyone knows of an aftermarket fuel pressure regulator that will work with the OEM fuel pump assemblyÖeven if the assembly had to be modified.
Hereís why I ask:
It started out the summer with backfiring, rough idle and hard starting. That problem was fixed with a new t-bap wiring harness and a new throttle position sensor and harness. Meanwhile another problem started up but was masked by the initial problems in the beginning of the summer.
Now my machine will run great for hours--and sometimes days--and then just die for no reason. Any RPM, any speed, it just dies--no rhyme or reason as to dry trail, wet trail, mud bog, hot weather, cold weather.
Another scenario is it will be running fine when I shut it off; and then when I go to start it again, it will fire up to normal idle RPM, run for a few seconds, and slowly trail off until it dies.
The rest is the always the same. If I try to restart it immediately it will seem normal for a second or two then die again. If I continue to try to restart it every minute or two, it runs longer with each subsequent restart, until finally it will run fine (minutes or days--who knows). It usually takes about 30 minutes to an hour for it to restart and run normally. It throws no trouble codes when it dies and the speedo is not flashing HOT either. The fan is cycling on and off when it needs to.
Sound familiar to anyone?
To date, this is what Iíve done to the machine this summer:
I've changed the fuel pump and filter sock inside the gas tank, and the voltage to the pump is good. I dismantled the entire fuel system, cleaned out the gas tank, gas lines and fuel rail, changed the filter and burned a tank of gas treated with Sea Foam. The fuel tank vent is also good. I've also covered the bottom of the gas tank with foil insulation.
The air filter is clean and the rubber intake boot between the air filter box and the throttle body is not cracked or rubbed through. The plastic throttle body adapter tube to the head is also in good condition. The clamps are tight in all the right places. The oil is clean and full as are all the other lubricants.
Iíve changed the t-bap sensor, installed the beefier harness (the original was broken on the inside), changed the TPS (which was bad and I thought would be the final solution), and adjusted the TPS to within a thousandth of a volt of factory specs (zero offset and idle voltage). The TPS output reads good at the ECU plug as well. Spark plugs are in good condition and the coil and the spark plug wires are new.
Iíve removed and cleaned the contacts on the power and fan relays and their sockets (they were only slightly dirty but seemed to be making good contact). The fan works as advertised. The resistance at the coolant temperature sensor and the crankshaft position sensor are reading within specs at the ECU plug.
Iíve checked continuity for every circuit related to the EFI and found nothing out of order, though that doesn't mean there's not a short somewhere after she gets warmed up. The battery is strong and reads 12.8 volts. The machine reads 13.8-14.1 volts at idle.
That brings us to the 24th of September when I thought I had it licked.
This weekend when it died again, I jumped off and hit the fuel pressure relief valve and got barely a dribble of fuel. The pump runs fine but I noticed it sounds different when the engine dies. Under normal circumstances, when I turn the key on it will usually run for 2 seconds and cut off sharply like there's real pressure forcing it to stop spinning, and this is as it should be. I noticed when it died, I would turn the key on, the pump would run for its usual 2 seconds, and slowly wind down as if there were no backpressure to stop the impeller from spinning.
I'm convinced the fuel pressure bypass regulator inside the tank is sticking open and dumping fuel from the pump right back into the tank instead of through the fuel lines, which causes fuel pressure to drop drastically and stalls the engine. My first bet is a shoddy valve, but because it starts up again after cooling off I believe it could also be heat related...or a combination of both. The other common symptom is it usually happens after riding for awhile, which would be about the time the fuel level has dropped below the level of the regulator.
It's just a theory, but it makes sense because I've read dozens of threads that describe the same symptoms/scenario: Engine dies when warm for no reason then starts back up and runs fine after cooling down. Nearly everybody tries to fix the problem with a new, aftermarket fuel pump but it rarely ever fixes it; however when people throw in the towel and buy the $500 tank assembly from the dealer, they say it works fine. The only other part inside besides the gas gauge sender is the fuel pressure bypass regulator. That leads me to believe that it's not the pump but the regulator that's the problem.
Oddly enough, nobody on dozens of forums Iíve read has found a replacement regulator to see if replacing it by itself might fix the problem.
That's it for the update.