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[TT600] Trouble starting and idling

6K views 30 replies 6 participants last post by  Tripps 
#1 ·
Hi guys,

I'm back. I have a TT600 (year: 2000).

I always had a bit of trouble starting my bike and the idle was very unstable the first 30 seconds - 2 minutes (depends on the day). I changed my battery last week and the issue has gotten significantly worse since then. But once the engine warms up, it seems to run just fine.

I had the battery checked and the voltage is at 12.6 which is fine.
I checked the IACV pipes and joints and they are all plugged in tightly and don't have a single crack.
I noticed that I don't have a breather hose coming out of my tank (nowhere to be found, previous owner must have lost it or removed it). I thought this could be the issue so I started the bike with the fuel tank cap open but it didn't change a thing.

Could it be an the idle setting are wrong in the ECU?

Any help is appreciated (although my mechanics skills are very limited!).

Cheers.
 
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#2 ·
You may have some adjustment problems. If the throttle bodies aren't synched, it's going to cause problems. If you add in a CO level (fuel idle trim) that's too low, it can make for idle surging. Depending on how far out of tune it is, the surging can continue for a while.
 
#3 ·
Hi Will,

Thanks for your reply and sorry for not coming back to you ealier, I was busy testing the bike.

So, last week I moved the fuel tank out of the way (can't remove it completely as the electric wire doesn't want to disconnect itsef). I cleaned a bit the inside, made sure that all the hoses and cables were propery connected. Put the bike back together and it started from the first time!
I tried to start the bike today and it doesn't start. I can hear the fuel pump priming when I turn on the ignition. When I try to start the bike the starter is turning but there is no ignition, there is a light fuel smell coming out of the exhaust (which is a good sign according to what I read in other thread) and sometimes I get a backfire. I managed to turn it on once, I waited a bit, put a bit of rev (2,000 rpm) but the bike cut off when I released the throttle.

Could it be the spark plugs? I've had issues to start the bike for a while now (but it always ended up starting) and there were also a few idle issues. All of which seems to point to faulty spark plugs according to what I read.

I would like to check the spark plugs but I'm not sure what I'm supposed to do once I removed the fuel tank. Do I have to unplug any hoses to remove the airbox or just release the strap? And after that?

(As you can probably tell, I don't know a lot about mechanics so any help would be appreciated).

Thanks!
 
#4 ·
I'm a little surprised the electrical connector wouldn't come off the tank. It should have a quick disconnect that comes apart pretty easily if you squeeze it to disengage a locking tab. I don't remember if it even has that - it's been a while. Worth a look.

The airbox just comes right off. If there's even a strap left at this point, remove that, then gently remove the boots to the throttle bodies. Same with the boots to the snorkles up front. At that point, you will see the spark plug wires disappearing into the top of the valve cover. The plugs are down in wells, below the coil. What may have happened is that the bike sat somewhere it could collect rainwater for a while, and the spark plug wells filled up, rusting the plugs. The coils are supposed to have a seal that keeps water out, but it's not always effective, and that means new plugs.

If that solves the problem, it's fantastic. You may also need new coils, depending on how long it sat and how bad the corrosion got.
 
#5 ·
I'm not quite sure why the electrical connector won't come off the tank. Either glued or too much dirt.

Anyway, I managed to remove the airbox and the coils. I didn't remove the spark plugs but as far as I can tell, they look fine. How am I supposed to test them (i.e. see if they spark)? Plug in the battery and try to start the bike? And is there a way to test the coils?

If everything looks fine with the spark plugs and the coils, what should I test next? (Detailled explanation would be much appreciated as I know next to nothing in mechanics).

Sorry if it's a lot of questions but I have a ride on Saturday with my club and I really wanna go.

And thank you for the help so far, Will!

P.S: The seals on the coils look just fine. I also checked the air filter and it looks brand new.
 
#6 ·
Pull the spark plugs and at least look at them. Replace any that are rusted, caked with carbon, etc. They should have a light color to them, not black, caked brown, oily, or anything like that Then reassemble everything. Use dielectric grease on the connection between the coil and spark plug. This helps seal out any moisture that gets in there. Once you have everything back together again, see what happens and we can think about other things if that doesn't work.

Fuel smell in the exhaust without it firing says spark problem, so we will have to think about what else that could mean if it doesn't run after you put it back together.
 
#7 ·
So, I removed the spark plugs and their tips were all black (burnt). I replaced them with NGK CR9EIX (iridium) spark plugs, put the bike back together and it still won't start!

No changes. The fuel pump primes; I can hear the starter turning over and over but no ignition; occasional backfire in the exhaust; light fuel smell coming out of the exhaust.

I have no idea what to do next. Any ideas?

P.S: I assumed the new spark plugs were "good to go". In other words, I didn't make any adjustements before fitting them. Was I right?
 
#8 ·
To add more information to the post above:

The ignition switch seems to work as when I push it, the headlight becomes weaker (I read on another forum that it is a good sign).

The clutch switch seems to work fine as when I try to start the bike without engaging the clutch lever, the starter just doesn't turn on.

I tried to start the bike with the side stand up but it doesn't make a difference.

When I try to start the bike in first gear (clutch in, side stand up), I can feel the bike pushing forward.

I hope that helps! =)
 
#9 ·
Does it sound like it's trying to fire, or is is just turning over?

Also, have you plugged in TuneECU to see if there are some other issues? That's probably where to start at this point. It may have been where to start back when.
 
#11 ·
TuneECU gives me an error about the air inlet temperature sensor. Currently in the process of checking this. But I don't think it's a reason for the bike not to start.

The battery voltage is at 12.45V. So, a bit low, but it should't stop the bike from starting. (The two times I had trouble with my battery, the voltage was so low that it couldn't even turn on the tachometer or honk).

I'm wondering if my sparks are actually getting any/enough fuel. As I can't disconnect the fuel pump from the tank, it makes it hard to check the fuel pump. But can I try to start my bike and then check if my spark are wet? (Also can I try to start my bike without the airbox?).

Cheers!
 
#12 ·
UPDATE:
1) I managed to fix the error that TuneECU gave me (Air inlet temperature sensor).
2) I checked the spark plugs by removing them from their holes and attaching them to the coils. I then pushed the ignition button and all four spark plugs gave me blue and frequen sparks.

So, since there seems to be no electrical failure and I'm getting proper sparks, it seems to me it's either the fuel injection or the air injection. I want to check the fuel injection (starting with the injectors). Anyone has any recommendation (tutorial) on how I should do this? (Keeping in mind I know next to nothing in mechanics).

Cheers!

P.S: I already checked the IACV cables and they seem all good (no crack, splits or such).
 
#13 ·
Did the bike sit for a long time? Perhaps it's got clogged injectors. Also, the fuel pump may be making noise, but it may not be getting you enough fuel pressure. The fuel filter could be plugged.

This is turning into an epic diagnosis.
 
#14 ·
I cleaned the injectors with carb cleaners and I got two strong sprays from each connectors. So I believe the injectors are good.

Do you recommend to only change the fuel filter or the fuel filter AND the fuel pump?

Thanks for your help so far, Wil.
 
#15 ·
How did you get the spray? Was it from pressure in the fuel rail? If so, then the fuel pump seems to be working. Without it you don't get fuel pressure.
 
#16 ·
How many mile are on the bike since the valve clearances were checked? My Sprint wouldn't start and on the advice of the guys here on the forum I checked my valve clearances and found that they were all tight on the intake side. After I got them back within the proper tolerance it starts every time. Just a suggestion but it seems to be a common ailment and frequent solution.
 
#17 ·
No, I sprayed carb cleaner through it. So I know the injectors are clean. But I don't know if they're getting enough fuel. I ordered a new fuel filter (from BMW, the KL 145).

Side question: My connector to fuel pump (under the fuel tunk) is completely stuck. Any tips to unstuck it? Any spray?
 
#25 ·
Update: So, I managed to remove the fuel tank connector. I removed the fuel tank and replaced the fuel filter. I also removed a bit of rust around the fuel pump and the bottom of the fuel tank. I put the bike back together but it still doesn't want to start! The bike is turning but no ignition =(

What are your suggestions?
 
#29 ·
This may sound silly but it is how I had to start my bike until I adjusted the valves.

Try to heat the engine. I have a small, electric heater that I bought at Sears (maybe you can find something similar at the Tesco- that's a UK company I think). It doesn't need to be full operating temperature, just try to get the engine to where it is warm to the touch, then see if it starts. If it does that's probably another indication that the valves need some attention.
 
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