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Major problems with 2007 King quad 450


josephnbl91

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My four wheeler when i first got it seemed like it was very slow when i first got it and it had no throttle response so i replaced the belt and cleaned all of the rollers thinking that would solve the problem from what i read on the forums. well it turned out that it wasnt. so i went to the next thing i took out the injector to check it out and i seen that there was a tiny bit of debree in it so i cleaned it and it seemed to improve a little bit. but still did not solve the problem. i later found out how to find the trouble codes out from the lcd screen using a paper clip on the diagnostic port and it showed the code which stood for no codes C00. i also forgot to mention that the throttle position censor is working perfect. before i started all of this the four wheeler ran just not to its potential. after my friend and i did the trouble code test the bike wouldnt even start anymore and the injector would spray for a few seconds for the start up then it stops and the fuel injection light comes on and blinks. the four wheeler wouldnt start anymore. i took it over to the local shop and they hooked it up to the computer to see if there was any codes and it still showed it was free of codes. they hooked it up to the fuel pressure gauge and we found that it was making 22 pounds and it should be making around 43. i then bought a new fuel pump and put it in. it now starts and runs for a few seconds and then it stalls out and the fuel injection light comes on again. which then leads me to think it is the ecu now but i want to be sure before i invest around $500 more into it. any opinions on whether or not anyone thinks this is the problem or if they have had a similar problem before would be really appreciated. sorry for writing a novel and not spelling very well. also i forgot to put the year in the title it is a 2007

Edited by josephnbl91
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i forgot to mention that the four wheeler was running very lean before you could pull the spark plug out and it would be very white. and from what i hear they are supposed to run a little on the rich side. at this moment while i have been working on it the air box is off of it and everything so i dont think that could be the issue.

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If it is running lean, then a clogged air filter is not likely, but running without the airbox lid will only make the lean condition worse. Have you tested the fuel pressure againg since you installed the new pump? I would double check the injectior to make sure it is clean and plenty of fuel is getting to and through it. I would try to explore every possibility before investing the $500 on a new ECU. Tank vent? Check the fuel hoses going from the tank to the pump for leaks. That could be how you were losing fuel pressure.

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no i havn't checked fuel pressure with the new pump because i dont have a fuel pressure gauge i got it tested at a shop. it seemed to improve though because the four wheeler now at least starts and runs for a few seconds then shuts off and then puts the fuel injection light back on and stalls out.

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meaning when you turn the key on the fuel pump relay clicks which means the pump is turned on and it puts fuel in the intake and then it is ready for start up. but after that initial start up it does not put any more fuel into it after the fact. if you keep cranking the four wheeler you will see the injector spraying fuel in but i guess it stops after the four wheeler starts which makes it stall.

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This is just a wild thought, but when you are initially starting the machine, the electrical system is running off the battery. After it is running, it really gets it's power from the alternator, some components, like maybe the fuel pump and injection system, run off the current that comes out of the regulator/rectifier. Try checking the voltage that is coming out of the regulator.

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hmm sounds possible. i know for sure now that the computer is fried litterally but im not sure if that is or was the only problem im hoping it is. my friend figured that if the computer was not working due to moisture getting in it some how (submerging the four wheeler) that he could get the moisture out by heating the ecu in the oven. i didnt know what temp. he did it on until after the fact but it was baked at 250 degrees for a little while. he said he plugged it in and it actually ran for about 30 seconds rather than just stalling after 5 seconds. but anyways seeing that it some what improved we thought that we should do it again. so we did and now it doesnt start at all. yes i know it was dumb to do this. he didnt just make up this idea his dad owns a generator repair business and he heats the computers of some of the generators and they start working again.

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hmm sounds possible. i know for sure now that the computer is fried litterally but im not sure if that is or was the only problem im hoping it is. my friend figured that if the computer was not working due to moisture getting in it some how (submerging the four wheeler) that he could get the moisture out by heating the ecu in the oven. i didnt know what temp. he did it on until after the fact but it was baked at 250 degrees for a little while. he said he plugged it in and it actually ran for about 30 seconds rather than just stalling after 5 seconds. but anyways seeing that it some what improved we thought that we should do it again. so we did and now it doesnt start at all. yes i know it was dumb to do this. he didnt just make up this idea his dad owns a generator repair business and he heats the computers of some of the generators and they start working again.

I've never heard that one...heating up in an oven. Why not just take a blow dryer to it? Is your ecm fried, or you don't know...the ecm sends a signal using throttle posistion, engine rpm, etc..to keep the fuel pump on or shut it off.

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I have heard of the oven trick but I don't believe you are suposed to use that high of temp. I thought it was 150* max. I have used a heat gun and hair dryer as well. Just two weeks ago I droped my cell phone in the dish water. Got the battery out ASAP and did the hair dryer for a while and then left it in the sun for a few hours. Works ok now.

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The best way to test it is to measure the output voltage with the engine running and see if the output is affected by changes in engine speed. I guess that would be kind of hard if you can't get the engine running. There may be some direct resistance tests you can do, a manual or a service tech at a dealership may be able to tell you if that is possible. Another thought is to hook the regulator up to a power source that is putting out about 16volts AC. Hook it in instead of the wires that come out of the stator going to the regulator. The output from the regulator should be about 12volts DC. But most people don't have 16 volt AC power sources just lying around. A dealer may be able to test it for you also.

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  • 2 weeks later...

Hello there.

I have come accross this problem and it took me along time to fix!

no one in Suzuki Australia has come accross it since the KingQuad has been out.

it is a long story... But there are few outcomes.

Due to the ECU being a "negative" ground switching device (meaning that when the ECU wants to turn "ON" somthing it dose not "send" 12V to a solinoid, rather it "receives" 12V from the device and finishes the circuit by earthing that 12v to ground)

thus it is very hard to diagnose problems with a ECU.

you have 2 possoble problems with your fuel pump relay not staying on.

1st there is 2 circuits inside the ECU that control the fuel pump relay. 1 is during the boot up (turn on for 2 seconds to build up initial fuel pressure and ECU gets to see if the pump is electricaly working)

2nd circuit is when the part the controls the fuel pump relay to "stay on" while the motor is running.

it is this circuit that seems to be the problem (same as the bike I was working on)

at this stage it is 100% recomended to get a electrical schmatic of the bike!!! (in the back of the workshop manule)

Due to all the possible problems (broken wire, dead relay, bad earth from ECU to bike, etc...)

I will just jump to the cool things.

The relay can be "tripped" turning the pump relay on, thus turning the fuel pump on, so that your bike has fuel pressure and it will most likely start up and run fine now.

by tripping I mean just putting a wire or pointy nosed plyers accross the part of the relay that gets joined when the relay is turned on normaly.

this will make the bike run, but there will be a constant fault code and a FI light on the dash...

I ended up finding the "pin" on the ECU and finding the wire in the loom that goes to that pin, and joined it to ground "earth" making the relay turn on.

it is a long story but the ECU just forgot or broke.... in that part.

it just would not earth to ground that pin, even tho it thought that it was (thus no fault code)

The bike can now be started by walking up to it and turning on the key, the pump turns on because of relay is shorted to ground not because of the 2 second circuit.

then the rest of the ECU will still work and the bike will run.

the only down side to this "fix" is that that bike must be started within 2 seconds (which is no big problem)

for eg. If you turn on the key and sit there for over 2 seconds, the ECU during the boot up and 2 seonds test, the 2 seond test will tell the ECU that the "relay did not turn off" and send a fault code to the dash and the FI light will turn on.

but the bike will run fine, and the fault code will clear when u turn the key off at the end of the ride.

But if the bike it cranked over before the 2 seconds are up, the bike is 100% normal and no fault code.

the bike I did this on was a LTA450 K8 that was drowned in the sea...

so initaly it came in for a relay due to corrosion on the pins and was fixed with a new relay. Then weeks later is started to glitch and not start up just like you were describing.

The owner just didnt want to buy a new ECU and I had to fix it cheaply (but who realy wants to buy a ECU!!!! I dont!)

oddly enough we ended up haveing a brand new LTA500XP the next week with the same problem, and the bike had to be "fixed" that same way so it could be sold (it was the last 500 we had)

When it comes back for its first service that bike will have a waranty repair on the ECU.

your bike should go to a shop who know what it is doing! and best of all if it has a LTA450 like your to swap over a new relay and ECU to test.

because if it ends up being the same problem as mine, then it is a easy fix with 1 wire being joined and earthed to the battery negative, it is neat and clean and works great.

I just with that I could tell you what caused it.

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dang that sounds dead on for the problem. thanks im going to try to see what happens when i get the new ecu in tomorrow. so you say i should be replacing the fuel pump relay also? oh and the reason i dont like to bring it to a shop is because the local ones we have in my area are not even near half as knowledgeable as you are. i ask them questions all of the time and they never have a solid answer.

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dang that sounds dead on for the problem. thanks im going to try to see what happens when i get the new ecu in tomorrow. so you say i should be replacing the fuel pump relay also? oh and the reason i dont like to bring it to a shop is because the local ones we have in my area are not even near half as knowledgeable as you are. i ask them questions all of the time and they never have a solid answer.

I think what he said was the part of the ECU that controlls the fuel pump relay is faulty. That is why he said you could manually turn the fuel pump relay on, hence overriding the ECU's control of the fuel pump. Like he said, use a wire to jump from the wire that feeds power to the relay to the wire that goes to the fuel pump. That way the fuel pump will be on when you turn the key on.

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yes. i got the new ecu yesterday and plugged it in to find that there was no change what so ever. i then jumped the relay and heard the fuel pump turn on and i got the four wheeler to start but as soon as it starts it stalls out again which is telling me that the injector isnt opening again. it only opens once for the initial start up. then it wont open again. that leads me to think that i have a faulty crank censor. im buying a new fuel pump relay because i know i need that for sure and im also going to buy a crank censor hopefully between the two they solve the problem.

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