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Discussion Starter · #1 ·
Good day!

A little background: I have a hobby of tinkering with motorcycles. I've restored and built a number of bikes. This is why my buddy contacted me last week.
His son traded his dirt bike for this sled (93 Polaris Indy 500 EFI). When they got it a few weeks ago, they had it running and could run it round the yard a bit on the grass. When he went out to start it recently after we got a bit of snow, it was completely dead. No response at all. My buddy knew I worked on bikes so he brought it over hoping I could help get it running. The young guy who traded his dirt bike for this thing is obviously pretty upset and I'd really like to help.

I've been doing some research on these machines, and this forum was where almost all of the good knowledgeable info has come from so far. So I thought I'd fire up a thread in hopes of enlisting some help. To be completely honest, although I've worked on other types of machines, I don't have experience working on snow machines.

Ok - the lowdown so far..

- Good spark at both plugs.
- I know that these EFI sleds require a juicy battery to start up. I have a trickle charger on the battery and it's > 13V.
- No electric start on this sled, just pull start.
- As I understand it, when I pull to start it, I should hear the fuel pump start up. I don't.
- I checked the fuel pump (by jumping it to the battery) it runs without any problems when wired this way.
- I replaced the inline fuel filter with a new one.
- I got a wiring diagram from this site, but it looks like someone has modified the wiring. (stock wiring diagram attached)
- My first thinking was to check fuses and relays. I can't find any fuses or fusible links anywhere.
- When I check the resistance across the two (black - four contact) relays mounted on the ECU, I get 100 ohms as expected, however when putting 12v across the other two contacts, I see no change in the 100 ohm resistance. I was trying to test these relays as shown on the instructions attached to this post.(relays(1).pdf) - it seems unlikely both are bad, so I must be doing something incorrect in my test? I'd love to know how to properly verify these relays are functional.
- Following that, it seems that the next step is to verify the ACS, as this component is responsible for firing up the fuel pump when the cord is pulled (which isn't happening).I found some guidance about testing the ACS but I don't understand it. I also can't find the actual ACS - I don't know where it's mounted.

I'm attaching a number of pictures of the wiring on this sled. Maybe it will help someone more knowledgeable than myself understand the intent of what has been modified, and what to do about it.

Please help if you can. I'd really like to get this sled running for my buddy's son. Any and all guidance is appreciated..
 

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I should check my sled to exactly how I wired it, but essentially the ACS fails on all these units. It was integrated to the V/R and after a set time of no engine running, tells the computer to shut off everything if the key was left on (when you went into the bar for a beverage).

You can be creative and try to run the fuel pump relay off a keyed power, or just have a separate switch for the fuel pump. That’s what I opted for. Flip the switch, turn the key and she starts in 1-2 pulls every time.

Edit:
My switch is functioning in place of the acs relay. The fuel pump relay is still activated by the ECU.
 

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Discussion Starter · #3 ·
I should check my sled to exactly how I wired it, but essentially the ACS fails on all these units. It was integrated to the V/R and after a set time of no engine running, tells the computer to shut off everything if the key was left on (when you went into the bar for a beverage).

You can be creative and try to run the fuel pump relay off a keyed power, or just have a separate switch for the fuel pump. That’s what I opted for. Flip the switch, turn the key and she starts in 1-2 pulls every time.
Thanks for the feedback. I tried powering the fuel pump directly from the battery and it still wouldn't start. How long should the fuel pump need to run to pressurize everything?
Is there anything the ACS does other than start the fuel pump when the cord is pulled?
Where is the ACS mounted?
Is there another way to check the EFI controller to ensure it's getting power when it needs it?

As you can see from the pictures, it looks like the previous owner of this sled did some wiring around the ignition, and there is what appears to be an extra switch (although I'd appreciate confirmation that the red switch is not stock).
 

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Heated grip controls and an enrichment switch are the other switches on mine.
The ACS is the same little box as the voltage regulator. Use a switch to throw the fuel pump relay instead of worrying about the acs and ecu.


Do you have fuel returning to the tank when the pump runs? You could adapt a gauge to confirm fuel pressure at the rail. Something around 45 psi I think. Spark plugs wet?
There are other sensors, coolant and airbox I believe the ECU is also looking for.
 

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Discussion Starter · #6 ·
Heated grip controls and an enrichment switch are the other switches on mine.
The ACS is the same little box as the voltage regulator. Use a switch to throw the fuel pump relay instead of worrying about the acs and ecu.


Do you have fuel returning to the tank when the pump runs? You could adapt a gauge to confirm fuel pressure at the rail. Something around 45 psi I think. Spark plugs wet?
There are other sensors, coolant and airbox I believe the ECU is also looking for.
I'm pretty sure the two switches on this sled are a) the heated grip controls, and b) another 'mystery' switch that was added afterward. I don't think it's the enrichment switch because there is no stock label describing it like the one in your video (thanks for that btw).

I saw some disconnected wires coming out from under the battery box, so spent a good 45 minutes removing the battery box last night. (what a pain). It looks as though the ACS was mounted underneath there. Now that the battery box is removed, I can see things much better and am hoping to begin investigating with the wiring diagram and my meter to trace some wires.

At this point, when I pull-start it, there is a good spark at both plugs, but the fuel pump does not run. Despite what I do with that 'mystery' switch, the fuel pump does not start. If I wire the fuel pump directly to the battery, the fuel pump will run - but if I try to start the sled while the fuel pump is wired to the battery and running - the sled still won't start..

My near term goal for today is to try and figure out where that other switch is wired into, and what the disconnected wires were under the battery box.

Is there a way to confirm that the ECU is getting the correct 'inputs' to run?
 

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Discussion Starter · #7 ·
Hello again

I've determined where the switch is mounted as it relates to the wiring diagram. (See 20201219_01.jpg (below)).

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The plug on the back of the ignition switch is completely disconnected. Electrical wiring Wire Technology Cable Electrical supply

When the 'mystery' switch is on, I can confirm that there is 12V up to the red wire on the ACS, but only 0.04V on the O/BLK wire that goes from the ACS to the ECU. This means that the circuit breaker is good, and also I am taking it to mean that the ACS is bad - since I saw another thread on here that indicated there should be 12V out of the ACS as well as in. Please confirm my conclusion if possible.

So, despite the addition of the 'mystery switch' - it does not appear to me that the ACS had been previously bypassed on this sled. If someone can provide an alternate wiring diagram or something like that describing how I can modify the wiring to bypass the ACS, I would be very grateful.
I will continue to look for one in the meantime.
 

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Discussion Starter · #8 ·
fyi: Found this thread that has been very helpful. I am including a reference here to help anyone else who finds this thread in the future.

 

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Discussion Starter · #9 ·
Ok, following the instructions on the other thread (referenced above) I tried jumpering the red and O/BLK wires as shown here.
This didn't seem to do anything. I tried pull-starting it a few times with everything connected, and there was no indication of any activity - I did not hear the fuel pump start.
Did I misunderstand the instructions on the other thread?


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Discussion Starter · #10 ·
I've got another theory?
Since the ignition is disconnected, it appears as though (on the wiring diagram) that for the sled to be "on", the R/W wire needs to be grounded.
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So I checked it, and it's definitely not grounded.
I then noticed that the other end of the wire (near the engine) is disconnected? Could it be that this is the problem?
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I can't seem to find the male part of the bullet connector that is supposed to plug into the red/white wire here, and I also can't find where it goes on the wiring diagram?
I can't see any R/W wires going into the ECU? If I check resistance between this open connector and the ignition plug, there is 0ohms, so I know it's the other end of that wire.
What is this supposed to connect to?
 

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Alright I’ve looked at the wiring diagram for a bit now. Looks like the ignition switch is currently being used for the hand warmers. Does the stock plug even match up to the ignition switch? Looks like not enough pins on the switch.

Have you pulled apart all wire connections to clean and grease?

Where does the other ‘mystery’ wire go? One end looks like the + battery post.

There are two relays, one for fuel pump, one is the acs relay. Make a jumper wire and figure which one is the fuel pump/acs. The acs relay when bypassed will make the fuel pump prime and then shutoff until the engine is cranked. The fuel pump one will of corse run the pump constantly. Leave the jumper on the acs for the time being until you get this running. Unplug when you’re not working on the sled.

Will the sled run (with the fuel pump on) and just a touch of throttle? This has gotten me on my sportsman in the past. Link for explanation of that.
 

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Discussion Starter · #16 ·
Alright I’ve looked at the wiring diagram for a bit now. Looks like the ignition switch is currently being used for the hand warmers. Does the stock plug even match up to the ignition switch? Looks like not enough pins on the switch.

Have you pulled apart all wire connections to clean and grease?

Where does the other ‘mystery’ wire go? One end looks like the + battery post.

There are two relays, one for fuel pump, one is the acs relay. Make a jumper wire and figure which one is the fuel pump/acs. The acs relay when bypassed will make the fuel pump prime and then shutoff until the engine is cranked. The fuel pump one will of corse run the pump constantly. Leave the jumper on the acs for the time being until you get this running. Unplug when you’re not working on the sled.

Will the sled run (with the fuel pump on) and just a touch of throttle? This has gotten me on my sportsman in the past. Link for explanation of that.
I haven't pulled apart all of them. (Although I have done many of them). This is an oversight on my part, and I will definitely do it. Thanks for the suggestion.

In terms of any mystery wire, look at the wiring diagram. It seems to represent the best absolute truth for the current wiring on this sled as best I can determine?

I tested both relays by testing coil resistance, and by energizing them and hearing the click. I had not tried jumping the contacts. Good idea, I will try that.

I tried jumping the fuel pump and the sled wouldn't run. It's been awhile since I tried that though, and I may not have been powering the ECU (by jumping the ACS red->O/BLK) at the same time. I will try this test as well!

Thanks so much for the suggestions, I will try them :)
 

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Discussion Starter · #17 ·
OK.

I've gone through some of the connectors and they actually look pretty good. I haven't gone through all of them yet though, but I wanted to report what seems like a development since I found the 'light' on the ECU.

I tried jumping the R>O/BLK wires at the ACS (to bypass it), and also delivering 13V to the fuel pump directly.
In this configuration after about 10 seconds, the light on the ECU becomes and stays solid red. No blinking at all.

I waited a good 60 seconds with the fuel pump running (thinking it may take some time to pressurize the fuel rail), and pulled it about a dozen times with zero luck. It wasn't biting at all.
In this configuration, I've still got a good spark when I attempt to pull-start, but no lights at all on the console.

What does the red light on the ECU mean? Is that a useful clue at this point?
 

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Discussion Starter · #18 ·
Looks like the ignition switch is currently being used for the hand warmers. Does the stock plug even match up to the ignition switch? Looks like not enough pins on the switch.
Correct, the stock plug does not match up to the ignition switch. The stock plug is just hanging there disconnected. This is how it was when I got it?
 

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I imagine it ran like this like you said, but let’s put the ignition switch back the way it should be.

When you jump the two wires on the self shutoff relay, as in my video, does the RDY light come on the dash? If not there may be something going on with that ‘mystery switch’ as I’m still not sure we clarified where both of those wires actually go to.

You can hear how mine runs in the video. Not normal for it to take so long to start, but the fuel pump only has to run a few seconds. I would check fuel rail pressure next.
The solid light on the dash does not correspond to any codes I have found, so that will take some digging to find what that means. Are the spark plugs wet after you try pulling a dozen times?
 

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Put everything back together and check to see if you have 12 volts coming out of this when you pull the cord with a multi-meter. You may have said but I did not see it. Just stated the fuel pump was not working.
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If you have 12 volts coming out of the O/BLK

Check this plug next
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