1995 RXL fires and dies - Snowmobile Forum: Your #1 Snowmobile Forum

YRR3 · 09-15-2009, 07:57 PM

Here is the deal... 1995 RXL with electric start will fire and die. I here the fuel pump come on for about 5 seconds and then I try and start it and it will fire and die right away. When I pull the plugs, they are wet. Spark test shows good spark. I pull the crankcase drains and gas will drain out (about two teaspoons). I was suspect of the battery, so I put a charger on it while trying to start it. I read here that the RXL is finicky about batteries, so I will try a new one..I have a manual and all componants that I can test without the Select Monitor, test good. This started last year and one day I just tried it and it ran fine. Put it away for the summer and now I try and start it and same problem as before. I had a spare fuel rail with injectors and pressure regualtor and swapped that out, but all that is left now (i think) is the ECU. Any thoughts???

**RJ Gleason** · 09-15-2009, 08:22 PM

Still flooded.
Put in new plugs.

JheLrey · 09-15-2009, 10:07 PM

Had one where you could hear the fuel pump prime the system, pull the rope, want to fire, but did not, and kept pulling nada. Reset the key and turn it all of the way so the pump would prime, same thing again. It was the ECU

mrholmquist · 09-16-2009, 08:58 AM

Start with a compression test followed by a fuel pressure test. The only way to properly test the fuel pressure is with a guage, you have a manual so it will explain the steps.

The way it is starting and dying sounds like the fuel line is rotted inside the fuel tank and causing it to suck air and not really get a steady supply of fuel. I know it looks like it is flooding but funny things happen when the fuel pressure is inconsistant. Also the way you say it was worse after sitting all summer seems to point to that fuel line. It seems to be a common problem and would be worth checking for prevention even if it is not your current problem. Pull the fuel line out from inside the tank and check its condition

TwinsofMLB · 09-16-2009, 11:45 AM

Couldn't it be the carb settings?

**RJ Gleason** · 09-16-2009, 12:31 PM

Quote:

Originally Posted by TwinsofMLB

Couldn't it be the carb settings?

No, it's EFI.

YRR3 · 09-19-2009, 04:46 PM

***UPDATE****
OK. Today I spent several hours getting intimate with my polaris manual and an RXL that right now, I dont like very much. Here is what I did today:
I checked the fuel line in the tank as Mr M suggested. It was good. There was some black particals around the inlet screen, but it was not restricing flow. I put the hose back in the tank and tried to start it again. It still just fired and died. Next, I hooked up the fuel pressure gauge and took some readings. The pressure is 38 PSI while the pump is running and 36 after the pump is done with its initial prime sequence. I tried to start it again and same thing. Next, I unscrewed the air temp sensor from the air box and plugged it in thinking that maybe because it wasnt receiving a outside air temp, that it was adding to much fuel at start up. (Ive been trying to start it without the airbox on) but nope. Still wouldnt start. I held the throttle wide open and tried to start it while the computer was in 'clean out' mode. It would start and die about 30 times and finally when it no longer would try to start, I let go of the throttle and tried to start it. (thank god for electric start!) THis time it started, but in doing so, it sounded as if it was running on two cylinders and then the third came in. (there has always been spark on all three). When it is running, it runs great. Good throttle response, etc. It smoked alot as it was clearing the gas out. Then I shut it off and tried to restart it. Started right up. THen I shut it off and let it sit for about ten minutes. Now it was back to the fire and die thing. So digging deeper in the manual, I pulled off the drop resistor and tested it. The manual says the ohms between the white and each of the black wires should be 6 ohm +/- 10%. Each terminal on the drop resister measured 6.6 ohms. within 10%. I did notice on the drop resistor that there is a ceramic coating and the coating is cracked and there is a scorch mark on the ceramic. It measured good, so I disregarded it. Then I ohm'd the TPS to make sure it was within tolerance. If i remember right at idle position it measured .648 (book says .400-.700) and WOT was 4.5. I jumped the black and grey wire on the diagnostic plug and pulled out an old code for the crank case temp sensor. I check the CTS, and it was within tolerance. I should mention that I am not getting any codes before startup or while it was running. Next was the last resort. I swapped out the computer. Same problem and no codes. I put the original computer back on. WHile I was trying to start it, it started but was running very low rpm and any crack of the throttle, would kill the engine. I started it again and this time while it was running at low rpm (lower than idle) I put a mirror and a light in each of the throttle bodies. Each injector, when I squeezed the throttle, would show a heavy stream of fuel (not a mist or spray). Is this normal?
I am certain that the problem is on the fuel side of things, but I am unable to pin point it.
THe only other thing that I can think of is the RPM sensor in the CDI box. Could it be bad to the point that it is thinking it is at a lot higher RPM that it actually it is? I dont have another CDI to try and I cant find a way to test it in my manual. Or something else that I just thought about is the timing. The center mark on the stator is lined up with the seam of the two crankcase halves. (havent checked to see if this is normal yet..)
Also, I put in a brand new today today. The voltage before starting it is 11.4 When it was running I checked the voltage...11.85. Shouldnt it be over 12 as it is being charged by the flywheel?
Guys, I tried to explain in great detail what the problem is and hope that someone can help. I like this sled, but soon it is going to be parted out if I cant resolve this.....lets here your thoughts!

JheLrey · 09-19-2009, 05:28 PM

Is your enrichment switch on?

**RJ Gleason** · 09-19-2009, 06:02 PM

Quote:

Originally Posted by JheLrey

Is your enrichment switch on?

Read the posts Troll

it's EFI.

mrholmquist · 09-19-2009, 07:04 PM

The fuel pressure is good , you dont mention compression but i assume you found no problems there either. Really sounds like it is overfueling . The mixture is mapped and controlled based on inputs mostly from the TPS then to a lesser degree temp inputs from the temp sensors and the baro sensor. Since you say you already swapped out the fuel rail and injectors to no avail that leaves bad sensor inputs or engine mechanical problems . (twisted crankshaft, broken piston skirts etc. ) Of course there is a chance the ECU is defective but personally I've never seen one fail in such a way to cause this condition. Havent ever seen the CDI cause anything like this either.

Pull back the rubber boot at the connector to the ECU leave the connector connected and gently back probe the TPS wires one at a time (key and kill sw on , engine off) while slowly operating the throttle. Use the millivolt scale on your meter and ground the black lead at the battery for the tests . Let me know what voltages you get when you do this.

The low voltage when the engine is running is definitely not right , especially with a new and fully charged battery. You may want to diagnose the charging system and see what you come up with there since you have a manual I wont go into that.
Normally low voltage will cause less fuel to be injected than too much but hey maybe you will come across something to explain the problem in the process.

JheLrey · 09-19-2009, 10:48 PM

There is an enrichment switch with EFI smart guy! (RJ) :-) My 92 Polaris Indy SP 500 EFI did... and when flipped on, it would run like garbage.

**RJ Gleason** · 09-20-2009, 05:55 AM

I know that some of those had a switch to change the timing for elevation and fuel................

YRR3 · 09-20-2009, 09:06 AM

Quote:

Originally Posted by JheLrey

There is an enrichment switch with EFI smart guy! (RJ) :-) My 92 Polaris Indy SP 500 EFI did... and when flipped on, it would run like garbage.

What is the little rubber button by the key? when I push it, the fuel pump runs?

YRR3 · 09-20-2009, 09:11 AM

Quote:

Originally Posted by mrholmquist

The fuel pressure is good , you dont mention compression but i assume you found no problems there either. Really sounds like it is overfueling . The mixture is mapped and controlled based on inputs mostly from the TPS then to a lesser degree temp inputs from the temp sensors and the baro sensor. Since you say you already swapped out the fuel rail and injectors to no avail that leaves bad sensor inputs or engine mechanical problems . (twisted crankshaft, broken piston skirts etc. ) Of course there is a chance the ECU is defective but personally I've never seen one fail in such a way to cause this condition. Havent ever seen the CDI cause anything like this either.

Pull back the rubber boot at the connector to the ECU leave the connector connected and gently back probe the TPS wires one at a time (key and kill sw on , engine off) while slowly operating the throttle. Use the millivolt scale on your meter and ground the black lead at the battery for the tests . Let me know what voltages you get when you do this.

The low voltage when the engine is running is definitely not right , especially with a new and fully charged battery. You may want to diagnose the charging system and see what you come up with there since you have a manual I wont go into that.
Normally low voltage will cause less fuel to be injected than too much but hey maybe you will come across something to explain the problem in the process.

Last year (when it was running right) I took it out for the only drive of the year and the pto crank went throught the case. So I did rebuild it with a used case and crank. 3 new pistons, 1 used cylinder, new gaskets, etc. so I would definetly rule out mechanical as it runs the same after the rebuild as it did before. I tried a different ecu and same problem.
Yesterday after my post I let the battery charge and I tried to start it...strated 10 times perfectly. Today, the battery was sitting at 14.2 volts and I tried to start it and sme flooding issue. It seems as if it is running in fail safe mode seeing how much fuel is being dumped in.

YRR3 · 09-22-2009, 06:09 PM

Mr M: The TPS reading is .455 at closed throttle and 4.2K at full throttle...

mrholmquist · 09-23-2009, 09:56 AM

Quote:

Originally Posted by YRR3

Mr M: The TPS reading is .455 at closed throttle and 4.2K at full throttle...

The readings you give for TPS are using an ohmmeter as the book lays out to test the component when it is not connected to the system.
I was asking for something a little different though. I wanted you to check it by leaving it connected to the snowmobile and back probing the connector. For this you must use a voltmeter , use the millivolt scale (0.000v). The computer receives a voltage from the TPS and from that calculates the throttle angle. This test is much more accurate than the resistance test you have done previously and also takes into account supply and ground to the TPS. Connect the black lead of your voltmeter to the battery neg terminal and probe all three wires of the TPS one at a time while slowly operating the throttle . The signal voltage (center wire) should be the only one to change based on throttle position and it should rise evenly and steady with no skips or irregularities as you SLOWLY open the throttle.

The key and kill switch should be in the run position but the engine should not be running.

Let me know what readings you get doing this test

Also did you correct the cause of it not charging the battery?

YRR3 · 09-30-2009, 12:27 PM

OK. I finally had an extra two minutes to do the voltage check. The olny wire that would give my the voltage of the three TPS wires is the white one. At idle it is .330 it will gradually and evenly increase with the throttle being applied. Full throttle is 3.556.

The battery charging issue seems to be corrected now that the battery is fully charged. I think I took the reading without the battery having a full charge. It is 12.8 static and 14.2@5000 rpm.

I tried starting it yesterday and it was flooding out at start-up. To prove that it is getting too much fuel at start-up, while it was running rough at below idle rpm, I disconnected the fuel pump and the RPM increased and it idled smoothly for about 2 seconds before it ran out of gas. Plug the pump back in and floods at start. Fuel pressure checked at 38psi, so its not the pump or the regulator. All I can think of is the dang TPS, but I changed it out and it does the same thing. HELP PLEASE!

zoomsfob · 09-30-2009, 08:25 PM

what about the actual fuel injectors themselves? you said they were shooting a stream of fuel instead of misting? I know injectors usually clog up and suplly less fuel, but have you used an additive in the past year or two that is possibly eating away at your fuel system?

mrholmquist · 10-01-2009, 05:23 PM

OK the voltage from the TPS sounds a little off. The Black wire is the ground so it is normal for there to be no voltage there, if you did have a voltage reading here it would indicate the ground was bad. The Red wire is the voltage supply and it should read 5 volts. This should be constant and is fed from the ECU. If you didnt have 5 volts here it would mean there is an issue with the computer or the wiring. I think something was wrong when you tested it because it would not be possible to get a voltage reading
on the white wire if there was no voltage on the red. The white wire voltage is derrived from the 5 volts on the red . The 'voltage you got on the white is a out of whack too. At idle it would be normal to read near .659 and wide open just over 4 volts. The voltage is very sensitive and the reading of .330 you mention would indicate to the computer a negative angle for the throttle plates. Since there is no such thing as less than 0 degrees of angle the computer would do strange things with this data. I suggest you go back and re test the TPS voltages , make sure you have a good ground on the black and 5.0 volts on the red. Adjust the TPS to .659v with the throttle released and verify you get over 4.0 v at the wide open throttle position , see if that is any better.

YRR3 · 10-02-2009, 03:04 PM

I set the TPS according to the book-- Disconnect the throttle cable and back off the idle screw so the throttle plates are closed. I will admit that I have the select monitor software (but no cord), and all the book speaks about is to adjust it the positive side ov zero. I thought that with a positive voltage, I was on the positive side of zero. WHAT DECIMAL IS THE POSITIVE SIDE OF ZERO? .659v is where it was originally when I had the problem. Is there a decimal to angle conversion formula? I think the book says to set it to 3-4 degrees. What decimal would that equate to?
If .330 is telling the computer it is a negative anfle, shouldnt it not be delivering fuel at start-up then?
I will retest the wire voltages and post them.

Thanks again for the help.