PKR

Hey guys I've stripped the carb and cleaned out again, didn't make any difference, unit won't start. Pulled old carb apart and cleaned and rebuilt it, didn't make any difference. Unit is getting gas and I have spark but it will only fire about once every 20 seconds of crank and then it is only one fire, no start. Started thinking maybe the timing was off, Checked the valve clearances and they were right on spec with the manual, so I'm assuming the timing is good. I think that leaves me with 2 other options to look at, the CDI (this has a new CDI in it) and the pulse trigger. I did the ohms tests for the stator and pulse trigger and they are all in spec with the manual. Took a acv reading on the pink wire at the coil (comes from the cdi) showed 26.3 acv with key on. Got no reading on the black and green wire at coil (this also comes off the cdi) Is there some way to voltage test the stator and trigger coil without a peak voltage meter or adapter, all I have is a simple multimeter. I'd also like to test the 2 wires at the coil for voltage while cranking. The manual has no specs on doing this so I'm not sure what I should be seeing for readings, I am assuming these should all be acv readings. Thanks again for all your help and insight. PKR

Thanks for the comments, I'm going to take carb apart again. It's a new carb, I've cleaned it twice but have found nothing. I think the extra wires from the carb are what they call a warming resistor and work with the electronic choke.

I have had this machine running and put about 4 hours on it but it would not idle great. Would fluctuate between 700 & 2000 rpm and usually quit at the low rpm. Spark plug would carbon off and have to be cleaned. Throttled up nice and ran good in mid and high range. Machine then quit and wouldn't restart, couldn't get it to fire. Checked everything, had spark, gas, etc. Thought spark may be weak so ordered a new coil. Machine sat for 3 weeks waiting on new coil. Installed coil and machine fired right up. Idled nicely until it warmed up and then rpm's were all over the place. It quit after about 20 minutes and then would restart. If I let it sit for a few days it will start but won't idle. Fuel/air mixture screw does nothing, can be screwed out or in and no change in idle. Only way to keep it idling is to turn the throttle screw way in and have it revving over 2000 rpm. As this unit sat for close to 14 years I have replaced the pulse pump, carb, CDI, spark plug and now the coil. What am I missing? I have done all the ohms checks on the stator, pulse trigger, etc and they are all good. I've took the carb apart to ensure it was clean, reset the float to be leaner as plug was indicating it was running rich. Didn't make any difference. Don't know where to look next? Also can anyone tell me what these wires are for that come off the bottom of the carb (see pic). Thanks for the help PKR

Problem solved. Pump tested good, I had my temp tank to high above the pump, that's why it free flowed through.

Thanks, I will give this a try.

Thanks for the reply. I don't think it would be pressure from the tank as I just have a small tank attached for testing. I did have the quad running for about 3 minutes before it flooded out. The float is screwed in the carb so I have to wait for a new one before I can run the machine again. I will try seeing if the pump will actually pump or just free flow. Other than that I'm thinking of sending it back as defective.

Bought a new pulse pump and installed on machine. Hooked everything up except the line to the carb. Opened gas valve and fuel free flowed through the pump. Should this happen or is this pump defective? Thanks PKR

Update: It was the CDI. Installed new one and spark is back and unit is firing. Now to tackle the gas side, as you can imagine it is pretty gummed up after sitting for 14 years. Thanks for all you help and ideas for testing the electrical on this thing. I've learned some more about testing for electrical problems that I can use in the future.

Quick update. One of the guys at coffee row had a friend that does all this trouble shooting. He came out did all his testing and said it was the CDI. I have ordered anew CDI and should have it next week. Will let you know if that works.

Thanks for the response. Not sure what you mean by the trigger coil? All I have is a cheap multimeter. It has ACV and DCV on it. The safety switch has it's own 2 wire plug that I disconnected. This is for the switch on the handle bars. The CDI has 8 pins but the plug only has 5 wires to it. Black/green, green, Blue/White, Black/Red and Pink. As for a service manual I doubt there is one for this unit as it was only made a sold for 1 year that I know of. Have not been able to find anything about it online. Thanks for the response. It will take a few weeks for me to find a coil. Once I have one I will let you know if that was the problem.

Thanks for the responses. These are the readings I got this morning. COIL - Primary was 4.2 ohms, secondary was 16.96 ohms. Tested for voltage - pink wire 12.0 vdc with key on and while cranking motor, Black/Green wire 0 vdc with key on and 0.3 vdc while cranking. STATOR - pins 1-2, 1-3 & 2-3 all at 0.9 ohms, When tested to ground they all showed open circuit. CRANK POSITION SENSOR - pin to pin 184.6 ohms, tested to ground both pins showed open circuit. CDI - Black/Green open circuit, Green 0.2ohms, Blue/White open, Black/Red open, Pink 1.0 ohms. Tested for voltage only one that gave reading with key on and when cranking was the pink wire, showed 23.8 vac and 11.3 vdc with key on and also when cranking. Unplugged safety switch, made no difference, tried new plug, made no difference. Rechecked all wiring around starter and eveything looks good. Battery is new. Not sure what all these readings mean as electrical isn't my bag but hopefully they point me in the right direction.

This quad has sat in a shed for the last 14 years as it won't crank over. I cleaned up some connectors and grounds and had the machine cranking and running. Pulled the starter off and had it rebuilt as connectors were all very loose. Reinstalled starter and now it cranks over good but I have no spark. If I leave it sit for a few weeks I do get a weak spark for about 10 cranks and then nothing. Any and all help greatly appreciated.

Thanks for the ideas, will check all the connections.

Sorry, I thought I had updated this post a while back but obviously I hadn't. After getting taking this carb apart several times and getting frustrated, I walked away and went fishing for the summer, When I looked at it again I took the carb apart and checked everything, mounted it back on the quad and just hooked up the gas line. Quad fired up right away and throttled up nice and idled nice. I then started hooking everything else up on the carb, vent lines throttle cables air box and filter. Quad ran good until I hooked up the line off the bottom of the carb (overflow line). As soon as I hooked this line up quad started blowing gas out the air intake. I removed the line and it ran great. This line has what Yamaha calls a pipe in it. It looks like it may be a oneway valve of some sort. I removed this "pipe" and the quad ran great. I looked at a few other Yamaha quads that have has carb jobs done at dealerships and noticed none of then had this "pipe" on them so I just ran a length of gas line off the bottom of the carb. Quad has ran great ever since. Owner took it hunter last fall and it didn't miss a beat and is still running great. Still not a hundred present sure what the purpose of the "pipe" is but that was my problem all along. Thanks to everyone that responded to this request. PKR

Frank Thanks for the reply. I had taken a gas sample from the tank yesterday and it looks good today, no sign of water. The air filter and everything else looks good. My plan today was to pull the carb but I decided to try to start it first. It fired right up and purred like a pu*** cat. I ran it around the yard for about half an hour and it didn't miss a beat. I'm not to sure what is going on. I'm starting to wonder if the kids are flooding it when they try to start it and sitting out in the cold it isn't clearing itself??? The only difference between it being at the neighbours and being at my place is it is left outside there and is inside my shop here. I'm going to move it outside tomorrow and let it sit for the day to see what happens.