presdme

Hey all this place is great!! I have been given a couple of sleds one a 1991 rxl 650. Did not run whe I got it but thanks to some previous posts here it will start now. It is running at very high idle and will flood real easy. High enough idle to engauge the clutch and turn the track. I have read in previous posts that the tps sensor should be at .6 to .65 on a volt meter or 1/2 a volt. Mine is regestering at 4.5 volts now. Did I read correct or was I misinformed. What would cause this dumping of fuel. When I take out the 3 case drain plugs gas does come out of all 3 of them. Thanks for the help and I cant wait to go 100+ mph on the snow.

mrholmquist

TPS adjustment with a digital voltmeter...................

....the black lead from your digital voltmeter should be
connected to the battery negative terminal for all tests

The tps connector has three wires

blk= gnd from ECU
wht= signal back to ECU
red= 5v supply from ECU

With the TPS connector connected and the ECU powered up
back probe the wires in the plug. The black should give you 0v indicating a good ground. The red should read 5.0v indicating a good supply. The signal voltage should vary with throttle position and yes it should read very near
0.659 v at idle .
If you are getting 4.5v on this wire at idle the TPS is shorted and fooling the computer into thinking the throttle is wide open and this would cause overfueling
at idle.

presdme

THANKS for the info. I did what you said but without the sled running, the tps read .7 volts. Does it have to be running? The motor is reving up and down enough to make the track spin so I dont wank to get in real close unless I have to.
Also after I let it run a couple of minutes it will not restart unless I drain the gas out of all 3 case bolts. Any thoughts on what might be causing that? Thanks again for the help!!

mrholmquist

I assume you have no faults blinking on the LED on the side of the computer when the engine is running or you would have mentioned it earlier.

It is a tricky thing to set the TPS with a voltmeter you must make sure your meter is set to the millivolt range ....three decimal places 0.000
The .7 volts you mention makes me think you are not using a small enough range on your meter. Make sure you see the signal rise evenly and smoothly as you slowly operate the throttle. At wide open throttle you should be getting over 4 volts.
Oh and no the engine need not be running to test. Once you switch on the kill switch and the key switch the computer "powers up" and you can test your voltages. Even after you switch off either or both switches the computer will remain powered up for about 10 min .

Other things to check in the case of overfueling are fuel pressure. If the return line was crushed kinked or blocked the fuel pressure would be way too high and could cause your condition. The only way to know for sure if the pressure is correct is to tee a guage into the supply line on the clutch side of the fuel rail . Specified pressure is 35- 37 psi anytime the fuel pump is running.

Also check the possibility of the injectors dripping. Pull back the throttle bodies so you can see the injector nozzles and cycle the fuel pump. Check your guage to ensure you have 35-37 psi and then look for any visual signs of fuel dripping from the injectors when the engine is stationary. The computer should not be opening the injectors when the engine is not turning and there should be no fuel coming from them.

If the above tests pass and the engine is still overfueling we will have to look at the temp sensor signals , to be sure they are accurate.

presdme

Thanks for the help, I did get the tps set thanks to you. Its a steady .67 to 3.97 wide open now. Is this close enough or does it have to be dead on?
It will idle down now but the flooding problem will still shut it down after a minute of running. Then it will not start untill I empty all 3 drain plugs. But the good thing is [mabe] its now showing a code of one long and two short blinks. After looking here I found that is the code for crankcase temp sensor. Is that correct? If so do you know of a way to test it or do I have to buy a new one? Thanks again for all your help!!
Oh is that the sensor that goes in the crankcase, under fuel rails, right side if sitting on seat?
Thanks again!!

mrholmquist

Sounds like we are getting there. The 0.670 v you are getting at idle is close but still a tiny bit high . It would read a degree or so high on the Select Monitor. I'd like to see it closer as it does have a large effect on the mixture. Maybe we should get the code looked after and then come back to the TPS adjustment. The proper adjustment procedure involves closing the throttle plates completely by loosening the cable and backing out the idle stop screw and then adjusting the TPS to read 0 degrees. The voltage you get with the plates in the idle position is not really accurate as it will vary depending on where you have the idle speed adjusted to.

The code 12 you are getting is indeed indicating there is either an open or short in the crankcase temp sensor circuit. Failure of the sensor itself is not common but it is fairly common for the wire to break at or near the plug which goes onto the sensor. Check the wire is in good shape in the area of the sensor and the plug is tight and making good contact. If that is good you can test the wire and the sensor at the ECU connector using an ohmmeter. Disconnect the ECU connector and turn it upside down. The top row of wires in the plug will now be terminal numbers 1 through 11. Terminal 1 will be a black wire and 11 will be a white wire. The CTS sensor wire is terminal 10 and will be yellow. With the black lead of your meter connected to battery ground you can carefully probe the CTS wire in the ECU connector with the red lead being careful not to damage the pin in the connector. You should get a reading of around 2.5k at room temperature. If you get 0 ohms or no reading at all disconnect the sensor and check right at the sensor . If you now get a good reading your problem will be in the harness. If the reading is still no good at the sensor then the sensor will need to be replaced.

presdme

Hey I finaly got to test the crankcase sensor. If I have my tester set right it says 1.7. in hand off the engine. Just for kicks i put it in the freezer for couple of minutes and retested it jumped to 3. something. Do you think its bad? Also does the ground from the battery go to the motor, reason I ask is i cant seem to get contitinuity from the battery ground wire to the motor. Will it hurt the track to let it spin while I rev up the motor? It will stay running if i keep it at 4000 rpm. try to idle and it floods. There is more gas coming out of case plugs at both end cylinders than middle one. Lots of ??s Thanks again for the help!!

presdme

also adjusted the tps to .659

mrholmquist

There should be a good connection between the battery negative and the engine block the ground wire should be bolted to it . Remove the wire and cleant the connections until you have a good ground.

The resistance readings you quote for the crank temps sensor sound fairly close depending on the temperature . Say you were testing in a fairly warm condition.
Essentially the resistance should be around 2.5k at 20 deg C and increase the colder it is . I assume you tested the yellow wire to the ECU and found no problems however the engine block needs to have a good ground for this sensor to function properly. I feel that if you repair your ground problem the code will go away and perhaps all your problems as well.

presdme

Off hand do you know where the engine ground wire is? Man that would be great if that were so!! I sure would like to smoke some of these new young ones that run around on their new sleds, yea that would be great!! THANKS !!

mrholmquist

If I recall correctly there was a ground wire which went from the chassis frame to one of the two water pump belt guard bolts on the 91 model.

If you cant find it put one on , the engine needs to have a good ground

Got2bFlyin

Im bumping this back up for I just got a 91 rxl wasnt running in 3yrs so when I got it home drained all contents out of the tank flushed the fuel system put in new filter and fresh gas cleaned the injectors and new plugs. Oh and it has a brand new battery. When I start it for the first time after a day or two, 2 pulls its going. but once I let it sit for a few min, about 2-5 it dies and then I cant start it.

I have bean reading threw old post about a light on the computer but I dont see one on mine. Im extremely new to these motors for I only bean working on cars threwout my life and just got into smaller engines not to long ago so Im still trying to get my bearings on this. got a manual ordered and on its way to my house so I can learn more but was wondering if anyone could help give me some senior knowledge on this so I dont have to worry about this in the winter when it comes time to play with it. Thanks

Got2bFlyin

Ok so I came home tonight tried to give it a start put the key on fuel pump went on then went off tried giving it a pull or two it sounded like it wanted to start but just could not keep going. what could this be from? its getting fuel because I can smell it and I can see the fuel going back to the tank when the pump goes on after each pull. there something im missing? If this was a carb I wouldnt have any problem but sense Im still learning this setup Im running into blanks rite now

Any and all advice would be greatly appreciated. Thanks guys