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Discussion Starter #1
I have a 2006 LTZ400. I've been all through the fuel system on this deal and I'm sure fuel is not the problem - so I've narrowed it down to electrical. Here's the deal:

Jump on it cold - turn the key, hit the starter and it starts right up. Runs like a dream. Heats up, cooling fan comes on, no temp light - everything seems fine - until it dies. If it dies for any reason: kill it, drop the clutch, go up a hill too big for the gear, whatever and it will not start using the starter. Turns over plenty, but won't catch. Choke on, choke off, little throttle, lot of throttle - doesn't matter. BUT - start towing it home, put it in gear and drop the clutch, and it'll fire off. It'll run again (like a dream) as long as you want but if it dies, you have to bump start it. The starter just wastes your time and builds your frustration.

Let it cool down say 10 or 15 minutes, and it will again start right up with the starter.

I've read about the valve clearance problems creating hard starting, but when it's cool, it starts just fine.

I talked to a shop guy at a local dealership. He's a lot of help (advice wise) and he thinks it could be the ignition coil or the stater coil (?). He told me to check online for the specs and use an ohm meter / volt meter to check readings against specs. He figures taking readings when it's cold and again when it's at operating temp will help narrow down the problem. I need some guidance on that though. The last volt meter I had I burned up trying to measure something.

Somebody PLEASE tell me the source of my problem.
 

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what are the valves set at ?
 

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Weak spark plug wires or coils can cause these kind of things. Fine when cold, but once they heat up, the resistance changes enough to weaken the spark to the point of no light off.

I would check valve clearance first, since it is a known issue with the Z. If that is all within specs, then start checking for spark problems.
 

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Discussion Starter #4 (Edited)
So I watched a video on checking valve clearances and found the specs for my machine on another post on here. But wouldn't the valve issue cause hard starting all the time?
 

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Discussion Starter #5
Weak spark plug wires or coils can cause these kind of things. Fine when cold, but once they heat up, the resistance changes enough to weaken the spark to the point of no light off.

What about the fact that it will still pull start when hot? Can a weak spark cause it to pull start but not start with the starter?
 

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I know you said you read about valves, but maybe the search results were terrible. Tight valves that are cold may still start. When the metal warms up, the clearance gets even tighter and would make the valves hang open. Bump starting gets the engine spinning fast enough to overcome that, but it's obviously not good to run the valves like that. Weak spark can show similar results, but valves are most common on these.
 
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Discussion Starter #8
Pulled the gas tank and plastic off today to get to the valve cover. Got down to the cams and valves easy enough, but took me two hours of measuring and researching to figure out the "T" comes up in more than one cam position. I FINALLY got it TDC with the caps at 10 and 2 and discovered the gaps were great! 0.15 mm intake and 0.25 exhaust.

I pulled the ignition coil off of it. It was rusty on the side opposite the bolt so I cleaned it up with a wire wheel. I also checked the spark plug for good connection. It's possible I didn't have the wire pressed down good on the plug. Ran out of time for a test drive, so the adventure will continue at least one more day.

I'm 98% sure it's electrical now. Any suggestions for how to test the ignition coil?
 

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I'd suggest getting a service manual. All that testing stuff is in there and it will save you time for sure.


Did you see the stickied topic on checking valves on this site.........it tells you about the stroke you need to be on for proper measuring.
 

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Discussion Starter #10
I'd suggest getting a service manual. All that testing stuff is in there and it will save you time for sure.


Did you see the stickied topic on checking valves on this site.........it tells you about the stroke you need to be on for proper measuring.
I read lots of stuff including the sticky topic on checking the valves. I just got in a hurry and didn't read or didn't realize the timing mark came around more than once.
 

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I have a Z that had the same issue. I avoided checking the valves due to all the feedback on "Not starting when cold". After swapping several electrical items, I checked the valves and they were tight. So, check your valve lash. It is not hard to do and not a bad thing to check just to know where they are.
 

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Discussion Starter #12
I have a Z that had the same issue. I avoided checking the valves due to all the feedback on "Not starting when cold". After swapping several electrical items, I checked the valves and they were tight. So, check your valve lash. It is not hard to do and not a bad thing to check just to know where they are.
Yeah, I got them checked. Your right, wasn't that hard. (once I figured out that the TDC mark came around more than once related to the cam rotation.)
 

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Discussion Starter #13
So I'm checking the ignition coil now. Took it off and checked with a cheap multi-meter. Primary coil at 2.5 ohms and secondary at 16.01 ohms. Can anyone tell me what the specs are? The only thing I've found so far were much, much lower.

Next step will be to compare ignition coil cold to ignition coil at operating temp.
 

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Primary spec is 0.1-1.0 ohms
Secondary is 6k-7k ohms
 

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Discussion Starter #16
So I'm checking the ignition coil now. Took it off and checked with a cheap multi-meter. Primary coil at 2.5 ohms and secondary at 16.01 ohms. Can anyone tell me what the specs are? The only thing I've found so far were much, much lower.

Next step will be to compare ignition coil cold to ignition coil at operating temp.
Rechecked the ohms and got the same measurements today. Warmed up the machine and measured again. Same measurements.

Ugh! What next?!?
 

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Discussion Starter #17
I'm measuring the coil off of the machine. Should there be any difference on or off the 4wheeler?
 

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Quote:
Originally Posted by amcf18 View Post
Primary spec is 0.1-1.0 ohms
Secondary is 6k-7k ohms


So my coil is showing too much resistance?
I don't know. If you checked it according to the book with a quality meter, I would say it is out of spec.
on the secondary side, you show 16 and spec is 6500 or so, I would say that is low, not too much resistance, but I'm electrically challenged..
 
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