Does it have a separate ignition module?
Polaris Sportsman 800 HO - Loosing spark/combustion...something
Starting out, I have a 2008 Polaris Sportsman 800 HO EFI.
The issue I have is that, when first starting and even just idling, there are zero problems with the quad. No extended starts, no hard starts...etc. It'll sit and idle just fine without a single hiccup for hours ( I know, i've done it recently).
The issues start after driving it for a little while, not a first, and not at the exact time each ride, but as a visual, from my house to my camp is about 1.5 miles of road, from my house, I can get all the way out to camp, and about half way back...around a mile or so, driving figure roughly 20mph +/- 5, and the quad will like lose power and bog down at throttle. It'll still run and idle fine, you can drive it still but only at very part throttle, give it throttle and it just bogs down. It'll restart without a problem as well. It's like one cylinder just dies (not sure, haven't actually tested).
Here's what I know as, admittedly, I haven't' done a whole lot of actual testing, but there's no oil in the coolant, no coolant in the oil, no boiling coolant, there's full oil in it, no frothy oil. I leiu of actual testing and diagnosis, i've kinda just thrown a parts cannon at it. It has two new spark plugs, new plug wires, new coil, new exhaust manifold gasket (possibly related, probably unrelated, as the last guy never tightened the bolts and it blew out the gasket).
There is a lot of blow up coming out of the oil dipstick area, though not really sure how long that's been like that, and not sure if there is supposed to be a certain amount of blow by, or what constitutes a certain amount. After replacing the coil, I drove it out to camp yesterday towing a 5x8 utility trailer with a tractor harrow in it.; started and drove fine until about 3/4 the way out to camp. Did the exact same thing, could hear an audible change in the engine and exhaust sound. Lost power and would bog down when given more than just a bit of throttle. However, on the way back from camp, after doing tractor work for a couple hours, I drove back to my house on the quad, towing an empty trailer, and drove the entire way without a hickup, not a single problem, and even sounded better than it has in a long time in general.
I'm really unsure of what else to look at. The internet is not helpful as everything seems to be for when the quad dies when warm, or wont start when warm...etc. Neither of those are the issue.
The issue I have is that, when first starting and even just idling, there are zero problems with the quad. No extended starts, no hard starts...etc. It'll sit and idle just fine without a single hiccup for hours ( I know, i've done it recently).
The issues start after driving it for a little while, not a first, and not at the exact time each ride, but as a visual, from my house to my camp is about 1.5 miles of road, from my house, I can get all the way out to camp, and about half way back...around a mile or so, driving figure roughly 20mph +/- 5, and the quad will like lose power and bog down at throttle. It'll still run and idle fine, you can drive it still but only at very part throttle, give it throttle and it just bogs down. It'll restart without a problem as well. It's like one cylinder just dies (not sure, haven't actually tested).
Here's what I know as, admittedly, I haven't' done a whole lot of actual testing, but there's no oil in the coolant, no coolant in the oil, no boiling coolant, there's full oil in it, no frothy oil. I leiu of actual testing and diagnosis, i've kinda just thrown a parts cannon at it. It has two new spark plugs, new plug wires, new coil, new exhaust manifold gasket (possibly related, probably unrelated, as the last guy never tightened the bolts and it blew out the gasket).
There is a lot of blow up coming out of the oil dipstick area, though not really sure how long that's been like that, and not sure if there is supposed to be a certain amount of blow by, or what constitutes a certain amount. After replacing the coil, I drove it out to camp yesterday towing a 5x8 utility trailer with a tractor harrow in it.; started and drove fine until about 3/4 the way out to camp. Did the exact same thing, could hear an audible change in the engine and exhaust sound. Lost power and would bog down when given more than just a bit of throttle. However, on the way back from camp, after doing tractor work for a couple hours, I drove back to my house on the quad, towing an empty trailer, and drove the entire way without a hickup, not a single problem, and even sounded better than it has in a long time in general.
I'm really unsure of what else to look at. The internet is not helpful as everything seems to be for when the quad dies when warm, or wont start when warm...etc. Neither of those are the issue.
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Does it have an oxygen sensor? If so unplug it and see if it changes anything.
Just throwing spitwads-
how do you feel about your fuel system?
You are adding air via throttle with not increase in power.
possibly fuel pump bad or starving from foreign object in tank/sock or air leak above siphon?
how do you feel about your fuel system?
You are adding air via throttle with not increase in power.
possibly fuel pump bad or starving from foreign object in tank/sock or air leak above siphon?
Nope, the ignition module is built into the ECMDoes it have a separate ignition module?
No 02 sensor, would be a good idea thoughDoes it have an oxygen sensor? If so unplug it and see if it changes anything.
Funny you mention this, as prior to yesterday I didn't even consider a fuel problem; I believed the whole problem to be spark related. However, looking up more info after I posted this thread and remembering when I replaced the spark plugs the plugs were not overly wet or gummed up which points to not a spark problem to me. Looking up more info, seems like there is a known problem with the fuel pump on the 800s overheating and not working properly or not working at all. Which would correlate to my issues as it's when the quad "warms" up.Just throwing spitwads-
how do you feel about your fuel system?
You are adding air via throttle with not increase in power.
possibly fuel pump bad or starving from foreign object in tank/sock or air leak above siphon?
Though at first I don't think it explains why it starts and idles without a problem, even when running rough, ti'll still start just fine. I suppose it would make sense that the fuel pump heats up, stops working properly, but still kinda "works", enough fuel to start and idle the quad, and will pump enough fuel to for sitting idle without overheating, but when it gets throttle and the pump has to work faster, it overheats and stops working properly until it cools down again.
That sounds accurate? or am I mis-thinking something?
Either way I guess, nobody in town had a fuel pressure tester that I wanted to rent, and with a whole fuel sending unit being only $50 (the fuel gauge wasn't reading correctly on the atv anyway), I figured what the hell, why not. Tore apart the quad last night, and got the fuel tank out. so it's sitting and ready for a new sending unit. Really hoping it gets here before the weekend so we can use for memorial day camp.
My Buddy has a Ranger 800 that I believe is the same year. Would do pretty much the exact same thing. It was fuel pump. He bough a cheap ebay one and it did it again a while later. Been good since installing OEM pump.
I bought the cheap ebay pump lolMy Buddy has a Ranger 800 that I believe is the same year. Would do pretty much the exact same thing. It was fuel pump. He bough a cheap ebay one and it did it again a while later. Been good since installing OEM pump.
Hopefully it's good for a year or two, then I will buy OEM. Just didnt' want to shell out the $400 for OEM
The cheap pump will at least be enough to prove if that's your issue or not
word on the street is OEM is shit, Quantum is shizzle.
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Small update, I bought the new unit, however either my polaris is not a 2008 but a 2007, or they used a 2007 part in it. The pump unit I bought is not right at all, as it attaches with a big plastic nut, and the one on the fuel tank has 6 screws that hold it in, which is the 2005-2007 style pump.
The cheapest I found the 2005-2007 part for is $250. So I think i'm going to just try swapping the pump itself between sending units and see if that solves the problem; then next time it takes a shit, i'll just buy the whole sending unit. In the mean time, i'll just do the "look in the tank" method of fuel level indicating.
The cheapest I found the 2005-2007 part for is $250. So I think i'm going to just try swapping the pump itself between sending units and see if that solves the problem; then next time it takes a shit, i'll just buy the whole sending unit. In the mean time, i'll just do the "look in the tank" method of fuel level indicating.
I am leaning more towards a fuel issue as well. Weak pump when warm. I also once had a generator in an RV that would only run about 15 minutes and then would shut off and wouldn't restart until the engine cooled off. It ended up being an old rubber fuel line that would swell up shut from the engine heat.
Id say let it sit and idle for an hour and then with out shutting it off, go take it for a hard ride and see what it does. Id imagine that fuel pump is going to run hotter sitting at idle with less airflow than cruising down the road. Every sportsman I've ever owned always seems to have a shit ton of heat coming out by your legs. It likely gets hot and weak and like you said, only flows enough fuel to idle.
Id say let it sit and idle for an hour and then with out shutting it off, go take it for a hard ride and see what it does. Id imagine that fuel pump is going to run hotter sitting at idle with less airflow than cruising down the road. Every sportsman I've ever owned always seems to have a shit ton of heat coming out by your legs. It likely gets hot and weak and like you said, only flows enough fuel to idle.
Finally got around to working on the Polaris; i've had the new sending unit for a week or so, but time...etc.
Anyway; I took the new sending unit apart, and when comparing it to the old unit it looks very similar, all the connections and such were the same. So I acutally tried swapping over everything removeable to my old unit; didn't quite fit. The float system was just different enough to not fit into my fuel tank. So, oh well. I just swapped the pump itself over, looked exactly the same as my old pump. Got the quad backtogether and at the least it started and ran just fine.
I did not have time last night to take it for a test drive to heat it up, but at the very least it's back where I started where it starts and runs. Should be able to take it for a ride after work today; hoping that solves the problem.
Anyway; I took the new sending unit apart, and when comparing it to the old unit it looks very similar, all the connections and such were the same. So I acutally tried swapping over everything removeable to my old unit; didn't quite fit. The float system was just different enough to not fit into my fuel tank. So, oh well. I just swapped the pump itself over, looked exactly the same as my old pump. Got the quad backtogether and at the least it started and ran just fine.
I did not have time last night to take it for a test drive to heat it up, but at the very least it's back where I started where it starts and runs. Should be able to take it for a ride after work today; hoping that solves the problem.
Little man, dogs, and I took the quad for a ride.
Same thing. New fuel pump didn't make a difference.
While it was doing...whatever it was doing, I took the fuel cap off and there wasn't any excess heat, and the fuel was still cool, so I don't believe it's the fuel pump ot a fuel pump overheating. Runs fine until it heats up, always about the same time, then like it bogs down and looses...something. It'll run ok at low throttle, 15-20mp, 3,000-3,500 rpm, but give it more throttle and it bogs down and backfires a bit, like it partially lost one cylinder or something.
Suppose a compression check cold and hot is next. Then I guess Spark test? It has new coil, new plugs, new plug wires. So really rhe only thing left would be stator, way I see it. If it was PCM, the pcm was not hot and it was not hot in the area around it, plus i'd think the problem would be different and it seems to be directly related to heat sink/soak.
Same thing. New fuel pump didn't make a difference.
While it was doing...whatever it was doing, I took the fuel cap off and there wasn't any excess heat, and the fuel was still cool, so I don't believe it's the fuel pump ot a fuel pump overheating. Runs fine until it heats up, always about the same time, then like it bogs down and looses...something. It'll run ok at low throttle, 15-20mp, 3,000-3,500 rpm, but give it more throttle and it bogs down and backfires a bit, like it partially lost one cylinder or something.
Suppose a compression check cold and hot is next. Then I guess Spark test? It has new coil, new plugs, new plug wires. So really rhe only thing left would be stator, way I see it. If it was PCM, the pcm was not hot and it was not hot in the area around it, plus i'd think the problem would be different and it seems to be directly related to heat sink/soak.
I am 90% certain it is not a fuel issue.
Went ahead and tore it apart again and swapped out the old fuel pressure regulator for the new one just to make sure, as i never actually changed it when i did the pump. And go figure, nothing changed. Still same issue. Found out some more info though.
When I put it back together I left off the plastics, when it started missing and backfiring, I drove it back to the house, prolly 4-5 minutes. I was able to get a look at the engine really good.
The right side exhaust pipe was red hot, like it was just heated up with a torch. Left side pipe was just fine.
So, my assumption is, the backfiring is coming from that cylinder, it's loosing Spark or compression (my money is on compression), and the excess fuel is igniting in the exhaust pipe Cause it's still getting hot from the one good cylinder.
So, think that answers my next step, compression test? What would cause a loss of compression when it heats up, cracked block?
Went ahead and tore it apart again and swapped out the old fuel pressure regulator for the new one just to make sure, as i never actually changed it when i did the pump. And go figure, nothing changed. Still same issue. Found out some more info though.
When I put it back together I left off the plastics, when it started missing and backfiring, I drove it back to the house, prolly 4-5 minutes. I was able to get a look at the engine really good.
The right side exhaust pipe was red hot, like it was just heated up with a torch. Left side pipe was just fine.
So, my assumption is, the backfiring is coming from that cylinder, it's loosing Spark or compression (my money is on compression), and the excess fuel is igniting in the exhaust pipe Cause it's still getting hot from the one good cylinder.
So, think that answers my next step, compression test? What would cause a loss of compression when it heats up, cracked block?
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