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Discussion Starter #1
I will start at the beginning, Didn't run when i bought it. It sat for two years, outside under a tarp in Minnesota. New fuel pump and it runs. But rod knocked, Fresh rebuild, Crank, rods, pistons, zero last cam, air filter, new battery, great voltage from regulator. But engine light on, and over ride button didn't work, plug in on left handle bar was corroded, cleaned that up, now over ride works and no engine code. Look at throttle side plug ins and that switch in throttle housing. Even put plastic between contacts to test. No different, Tried without air filter, same thing. Then pulled muffler off, same thing. Check contacts on throttle positioning censer, injectors, and map censer, all nice. I runs great till half throttle, then just bogs, let up a little and you could drive all day. Anyone??? before I start throwing more at it, LOL...
 

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Discussion Starter #2
Did some more testing, The injectors spec is between 13.8-15.2 ohms, Mine are 11-12 ohms. I also tested the TPS, with ohm meter its good, but at wide open throttle it has 3.84 volts out. I know it only gets 5 volts to it, do you think it should have a little higher output???
 

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On the sensor, they use a 0-5 volt reference, with a .5-4.5 volt working range. First, just to be safe, check your fuel pressure and make sure it's at spec. I don't know if its' the same as mine or if the specs are the same, mine is a 2015 xp 1000, but i'll give you the test specs for it. Looking at the connector coming from the tps, there should be three pins in a triangular connector. The pins should be numbered from 1 - 3. the resistance readings should be as follows, providing again if it's the same as mine. This is directly from my service manual:

2 -3: closed to open, 1000-5000 ohms, value should change smoothly as throttle is opened and closed. You're allowed +/- 1k ohm
2 -1: closed to open, 5000-1000 ohms, value should change smoothly as throttle is opened and closed. same allowance.
1 - 3: open or closed, 5000 ohms +/- 40%. Reading should not change with throttle position.

Incorrect impedance injectors can have an effect on it as the drivers may not be able to operate them correctly..

Are you sure it's an electronic issue and not mechanical? When you say it bogs, do you mean wants to die out or just falls flat on it's face? Here's how I look at it: Bogs at the hit of the throttle and blubbers = too rich. Stumbles at the opening of the throttle and wants to shut off = lean.

What do the plugs look like? Are you getting 100% throttle AND tps?

what's the fuel pressure at WOT?
 

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Discussion Starter #4
Thanks, my TPS ohms are ok, But wide open throttle only 3.84 volts coming out. I think thats to low. I have a new fuel pump in it and starts great. I have a pressure test kit coming to check that out. What I mean by bog is, front dead stop, if you hit it to half throttle, it will spin pick the front up about an inch and just GO. But if you push it farther it just doesn't do anymore, kind of dies sum, let up just a little and it just rips again. Its like it doesn't get any more fuel after half throttle. Just put new OEM injectors in, and same thing. Plug look nice, not black, nice tan.
 

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Thanks, my TPS ohms are ok, But wide open throttle only 3.84 volts coming out. I think thats to low.
If your TPS checks out on ohms, then the volts are where they should be. One is tied to the other. You can't have correct ohms at the tps yet have low voltage, simply doesn't work like that. Ohms law proves that.

The condition you're talking about could indicate two things. You need to check running fuel pressure and compare it to specs. There can be issues with new parts as well, so you can't assume they aren't the problem just because they are new, they must be verified. Going off your description, it almost sounds like it's getting too much fuel and not enough air. That would cause a "blubbering" or bog that would clear up when you back off the throttle. The other would be an overly lean condition caused by lack of fuel, which is generally called a "stumble", where the engine tries or does shut off and there is little to no response until the throttle is backed off. This can be caused by a fuel restriction, such as a partially plugged hose, lack of fuel pressure, etc. If I heard what the machine was doing, I could better get an idea of what could be wrong. Some people will confuse a bog with a stumble and vice versa...

If you open the throttle up all the way when this happens, does it shut off or keep trying to run?

One more thing to check. Take the top cover off the throttle on the handle bar. Inside is a switch. When you look down at the top, you'll see a small square hole. There is a switch connected to the throttle that basically cuts out the throttle. There is another issue that's been found as well. I'll also include a link on how to adjust a tps.


I'm not saying that your tps isn't at fault, as it could be. But from what your describing it sounds like something else to me. Hopefully something in those videos will give you some direction.
 

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One other thing to check, and this slipped my mind completely, is the MAP sensor....if it isn't working right or is very dirty, it can't sense the airflow like it needs to. That will also cause the issue you're having...just something else to check.
 

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Discussion Starter #8
I have a new TPS i'm going to try today, also have a map sensor. I have been through the videos you posted before I posted here. I even put plastic between the contacts in the throttle switch to test that out. I have no engine codes. You asked if it keeps running when you push the throttle past half way, yes it keeps running, but does not increase and kind of has less power, let up some and its perfit running again. No black smoke ever. I will post back after the map and TPS, THANK YOU for your help. I have never been this stumped before, LOL.
 

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One way or another we'll get it figured out....

ADD NITROUS!!!!
 

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ive read the thread before and briefly skimmed it now and my thoughts are have you tested the fuel pressure??
 

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Discussion Starter #11
ive read the thread before and briefly skimmed it now and my thoughts are have you tested the fuel pressure??
That is next, the new TPS and the new map sensor did not change anything. I'm thinking fuel pressure also. I have a fuel pressure gauge kit ordered.
 

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Ok good keep us posted!!!
 

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Discussion Starter #13
I have seen problems with the fuel pressure regulator, but then they don't idle, or low fuel pressure they don't start. If I don't go over half throttle, I have driven it up to 5500 rpms. I will post when I get the pressure checked. THANK YOU!!!!!
 

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Discussion Starter #14
I'm trying to up grade to a XP, but I'm about to the point of keeping my old 800 in my profile pic. The 800 went through the ice one spring and sat on the bottom for two weeks before ice was gone and I drug it out. Flushed it many times, and it has run for years, just can't kill it.
138490
 

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Discussion Starter #15
Just for fun today, I pulled the fuel pump assembly out of the tank. Took the fuel pressure regulator off, and push on the metal diaphragm and blew air through it. Put it back together and its way better, not full throttle yet but close. New Regulator on ORDER!!!
 

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What is your fuel pressure?
 

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And what pump did you use?
 

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I had fuel pressure issues on my xp1000, oem pump failed. It was suggested to me to get a Quantum replacement...it was money well spent.
 
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