Motor Died and wont start...troubleshooting help!

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amp3d

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Hey Guys,

Yesterday after running the baja for about an hour with a new WT-990 carb, the truck flipped and just shut down. Have not been able to get it started since.

I have tried everything, and the coil seems to be working fine, I get a good spark and the gap on the coil seems ok.

That said, I'm trying to figure out if the problem is with the carb. It doesn't look like that much fuel is making its way into the motor. I cannot seem to flood it and although it looks like a tiny bit of gas is going in, there definitely isnt much.

I just removed the carb, and I'm wondering if anyone knows how much suction there should be on my finger if I plug the intake manifold.

Should I feel much when I pull the pullstart?:mad:
 
I had the same problem twice. First time was the vent on the gas cap. Pull out the rubber seal then re install then give it a go. If that doesn't fix it then most likely its the coil wire. When my wire went bad i still had spark but the wire wasnt making good contact to the stud in the coil. So try it without the cap if it goes then it was just the vent in the cap.

If the cap is not the problem its your wire most likely. I can sell you one for $10 shipped in the usa by first class maill or add $4 for priority. The wire is a accle copper core super stock wire.
 
I should have mentioned all the troubleshooting we went through at the track yesterday actually.

We checked the coil gap and all was fine, but reset it anyways to about a business card thickness...

And as for the gas cap, I don't usually get that problem because I use the snappy RC fuel line kit with the extra vent :)

For troubleshooting purposes though, I even tried to start with the gas cap off in case the vent was faulty, and still had the same problem.
 
bhilly82 said:
I had the same problem twice. First time was the vent on the gas cap. Pull out the rubber seal then re install then give it a go. If that doesn't fix it then most likely its the coil wire. When my wire went bad i still had spark but the wire wasnt making good contact to the stud in the coil. So try it without the cap if it goes then it was just the vent in the cap.

If the cap is not the problem its your wire most likely. I can sell you one for $10 shipped in the usa by first class maill or add $4 for priority. The wire is a accle copper core super stock wire.
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Im still getting a decent spark, I don't think that is the problem?

That said, I can't seem to intentionally flood the motor. I'm not getting much gas into the engine I don't think.

I swapped back to my other carb and it seems to be doing the same thing...any ideas why gas isn't making it to the motor if the carb doesn't seem to be the problem?

Even with the gas cap off...and I can see fuel filling the bulb on the carb and squirting into the return...
 
Also make sure the fuel lines arent hooked up backwards....lol.....easy stuff is easy to overlook
 
jw32baggs said:
just an idea, check the fuel filter in the tank itself..it might be clogged.
Click to expand...

thats my next option, and if that is the solution Im going to be mad at myself!

That said, I can prime it ok...still should check the filter tho eh?
 
I bet it's your coil wire. Mine did the same thing I couldn't flood it either. Try spraying some wd-40 down the spark plug hole re install the plug and see if it tries to run. If it just pops its your wire. But if it runs for a little bit then it's something else. You can run another wire then the one's I sell. I just had the samething happen to me. It would show spark on the plug but would not run at all just a little pop with starting fluid sprayed into the hole. And my problem started after a flipped it jumping a speed bump. What happens is the copper in the km wire is only like 5 copper strands of thin wire and the terminal ontop of the plug gets loose, so the electricity has to jump a gap twice and every gap it jumps you loses voltage. You can also have the same happen at the lug of the coil.
 
bhilly82 said:
I bet it's your coil wire. Mine did the same thing I couldn't flood it either. Try spraying some wd-40 down the spark plug hole re install the plug and see if it tries to run. If it just pops its your wire. But if it runs for a little bit then it's something else. You can run another wire then the one's I sell. I just had the samething happen to me. It would show spark on the plug but would not run at all just a little pop with starting fluid sprayed into the hole. And my problem started after a flipped it jumping a speed bump. What happens is the copper in the km wire is only like 5 copper strands of thin wire and the terminal ontop of the plug gets loose, so the electricity has to jump a gap twice and every gap it jumps you loses voltage. You can also have the same happen at the lug of the coil.
Click to expand...

Very interesting, I will look into this next.
That doesn't explain why the plug looks dry though does it? I don't see the relation...

Maybe I should also note I just found some fuel in my velocity stack...where the air filter is...that probably means some sort of blow back or something? Could this have affected something?
 
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amp3d said:
Very interesting, I will look into this next.
That doesn't explain why the plug looks dry though does it? I don't see the relation...

Maybe I should also note I just found some fuel in my velocity stack...where the air filter is...that probably means some sort of blow back or something? Could this have affected something?
Click to expand...

Yes bad spark. You don't have any exhaust to help pull fuel into the cyl so you are building to much fuel in the crank case. With a tuned pipe it scavenges the burnt fuel out which also helps pull in fuel/air mix.

Is it harder to pull the rope now? If so your spark is not burning the fuel/air.
 
bhilly82 said:
Yes bad spark. You don't have any exhaust to help pull fuel into the cyl so you are building to much fuel in the crank case. With a tuned pipe it scavenges the burnt fuel out which also helps pull in fuel/air mix.

Is it harder to pull the rope now? If so your spark is not burning the fuel/air.
Click to expand...

Its hard to say if it's harder to pull. Id say perhaps less smooth? If that makes sense...

Your theory makes sense, and you arent the first person to say the spark may be weak, so I'll give this a try :)

Fingers crossed!
 
after checking some more stuff, I am now convinced that the motor is not sucking in any fuel from the carb. I have tried 2 carbs with the same problem.

The carbs are working fine because it's dumping gas into the bottom of my carb, even spilling into the air filter stack.

Any idea what would cause the motor to not be pulling the gas in?
Gaskets? I have no idea!
 
Check your cly compresion. I almost think you are just worried and looking to find a problem thats not there. Since you said it was running fine before the roll/flip its telling of a few things it has to be since the roll can only do so much. I don't think its anything to do with the fuel side. You need to think about it a little bit. The motors draw very small amounts a fuel and aur at idle which is around 2-3k rpms. Niw when you are just pulling the pull start. Which means there is very little suction at start up with 500rpm for a second during your pull. These engines push and pull air threw the carb ever rev of the crank. Thats were the fuel in your stack is coming from.

Plus you said in the pm its not as smooth when you pull the rope. That means combustion is out of time. The wire is in the post and hopfully you will get it by the weekend. See if your freind will let you mount his coil on your motor and see if it works then you know that wire will be the fix.
 
thanks so much for your help and support. I look forward to seeing if you are correct! I sure hope you are! If so, I owe you bigtime!
 
Just hope the wire does not get stuck in customs On either side. Also if the wire is too long you can cut it down then take a knife and cut the yellow sleve and screw it back in.
 
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