Suzuki King Quad 700 problem

[NZrider]

My king quad 700 runs rough when cold then won't start some times but not often when it's hot. And occasionally smoke's a lot when it's cold I'm guessing that's rings but I'm worried unless it's causing the other problems

 

 

 

All help is appreciated thanks

[Mech]

Have you had the spark-plug out and checked.. The oil might be fouling the plug.

Check the plug for traces of oil or carbon caused by burning oil, and change the plug if it's dirty. EFI engines are quite particular about the plug condition and gap.

Smoking at start up is often the valve guides leaking oil down into the cylinder when it's sitting.  Rings smoke under different circumstances to valves.. If the plug is oily we can do some tests to tell if it's rings or valve-guides.

[NZrider]

I've put a new plug in and didn't do anything. Should I try a hoter plug?

[NZrider]

When it smoke's it doesn't run rough but it doesn't smoke that often and it doesn't always run rough.

[Mech]

So this is a fuel injected bike right ?  If the plug's not getting fouled by the oil then the oil probably isn't causing the rough idle.

First thing I'd do was do a basic tune, plug, adjust the valves, clean or change the air-filter, check for any air leaks into the inlet manifold, vacuum hoses, change the fuel filter, check the exhaust for leaks, adjust the idle speed and mixture if that's possible.. If it's EFI I'd check for trouble codes. I'd also check the compression.

Then I'd take it for a ride and check how it ran under a load, and on very light throttle settings. EFI engines are tricky beasts and they self adjust a lot so they don't behave like carb bikes do when they have a problem. Quite often with EFI the symptoms are mainly things the bike is doing to compensate for some very small problem(like a big plug gap) that you'd hardly notice on a carb bike. Any small differences you might see in it's running now compared to how it used to run could be important.

 

[NZrider]

I've done everything other than compression test and valves.

It idles fine but when you give it throttle in gear moves really slow runs roughly and dies but if you let it idle for 5 minutes or rev it in neutral until it stops running rough because it doesn't die in neutral it works fine.

Thanks 

[Mech]

Ok, that's helpful.. Might pay to check the temp sensor reading.

I suppose you have checked for trouble codes ?

What year is this bike ?

Edited October 29, 2023 by Mech

[Krazo]

wealth of info Mech.  appreciate your contributions.

[Mech]

Thanks Krazo..

[NZrider]

Yeah checked for trouble codes.

How to I check temp sensor reading

Year is 2006

Thanks for your help

[Mech]

You need a service manual. There's likely one on this site to download. That will tell you how to check the temp sensor.

The manual should say how to test the throttle position sensor and the air flow or air pressure sensor.. Any of which could cause this, (what sounds like), lean mixture. If you can you could also check the fuel pressure. That can be checked with a bit of experience just by holding the fuel hose to the injector while you turn the key on. The hose will bulge if the pressure is the required 50 pounds. If you can barely feel the hose stiffen or bulge then it might be low fuel pressure.

Tell us more about this problem.. Have you had the bike for long, has it been parked up or did the problem start while you were riding along one day, has it got gradually worse and how long did it take to get this bad, or did it just happen over night, is the fuel fresh.. ?

[NZrider]

I bought it 6 months ago and was told it needed a top end rebuild but what i didn't know until after I bought it is that it had previously cooked the ecu he got it replaced and it didn't run good he sent it back to the bike shop and they said it needed a rebuild but I found that the fuel pump was the reason it didn't run good so I replaced the fuel pump fuel injector spark plug wire because it was bad all of which as fixed all of the other problems and I wasn't that worried about this problem since it runs fine ones it's warm and I've put about 1100km on it but it would be nice to fix

Thanks

[Gwbarm]

Good stuff Mech! It does sound like a fuel delivery problem, but with all the sensors you need a manual like Mech suggested to do the diagnosis. You might have already done this, but a fuel injector cleaner wouldnt hurt and check all the connections at the sensors.

[Mech]

Yup Injector cleaner may help.. Simple thing to try.

[NZrider]

[Mech]

That sounds like a real piece of sh**..  I would have to fix that !

That's not firing at all when it's missing like that. . Are you sure the plug's gapped right ?

 

 

[NZrider]

It's a new plug so I would of thought it is I'll check

[Gwbarm]

It could b e spark, not advancing properly, but it sounds like its sucking in too much air causing a lean mixture, as you increase the speed of the engine, and as you go higher with speed, more fuel going in, it seems to level out a bit , i would check to make sure the manifold gasket has a good seal.

[Mech]

If it idles good then I wouldn't expect it to have a manifold leak..  I'm thinking the coolant temp sensor, the air temp sensor, the air-flow/barometric sensor, or the throttle position sensor showing the ecu a wrong reading and so causing the mixture or timing being thrown out and making it run bad..   It would be an easy thing to check if you could connect a laptop or had the dealer ecu reader. Otherwise it's a matter of getting the manual and a multi-meter and starting to test/check all those sensors. If all the sensors are delivering the right figures right at the plug going into the ecu, then I'd check all the earths and power supplies to the ecu and all the sensors, and if all of that's good then the manual will say to try a known good ecu, or try the suspect ecu in another bike..