Cutting out/backfiring

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autox7 · #1 Post by **autox7** » Sun Oct 19, 2003 5:36 pm

First let me give you the quad specs:
2002 Speed
Stock motor
Stock mapping
Slip on Big Gun exhaust.

I pulled my motor to check all of the crank plate bolts and the tranny cartridge bolts, and then consequently put the motor back in. While the motor was out, I also re-routed the oil lines to prevent blow back into the airbox.

The motor starts up and runs fine, however if you put a load on the motor it begins to cut out. Specifically, when I get to about 3/4 throttle, the motor hiccups REAL hard. Then it backfires and then it dies. It will idle fine, and just put around fine, but under any sort of load, nothing.

I first thought maybe and exhaust leak, but I checked the exhaust and no dice. The fuel filter is brand new, and none of the fuel lines are blocked. I tried running it with the air filter and without, same result. (not that i advocate riding without the air filter)

Any suggestions?

wistech · #2 Post by **wistech** » Sun Oct 19, 2003 6:00 pm

recheck the rubber manifold is secure from the head to the airbox.physically check all electrical connections like the fuel injectors and ground to the battery. And of course the fuel line orings and quick connects.

autox7 · #3 Post by **autox7** » Sun Oct 19, 2003 6:04 pm

Been there, done all of that. The only thing that is new on the bike is the spark plug. And it is the same as the one that came out.

This has got me baffled.

wistech · #4 Post by **wistech** » Sun Oct 19, 2003 6:17 pm

Is it possible the fuel line has a kink in it from your hose reroute. I can remember the fuel lines were stretched pretty tight over the head on my speed when i did my crank bolts in march. They have that heat wrap on them so it will be hard to tell. A fuel pressure check would show this right away.

blaze#52 · #5 Post by **blaze#52** » Sun Oct 19, 2003 6:58 pm

hey, with that big gun muffler you are allowing better exhaust flow than stock, i would put a blaze or moto map in and see what it does, plus you are going to get some more hp.

jfarrar · #6 Post by **jfarrar** » Sun Oct 19, 2003 10:33 pm

check your grounds.mine did this and i forgot to hook up a ground wire.same exact symptoms.if not try recalibrating your throttle.

autox7 · #7 Post by **autox7** » Mon Oct 20, 2003 1:29 am

I'm convinced that it is something in the throttle. I took it out and tried to ride it hard this afternoon. Sometimes it ran fine, sometimes not.

It acted like it was getting flooded. It would run for a while and then just backfire and shut down. For example I was flat out in 5th gear one time and then no throttle response. Nothing. The bike just coasted to a stop. It started right back up, but I don't understand.

If there is a ground other than the battery ground, please tell me where it is. The battery ground is good, the battery terminals are hooked up.

There are no kinks in any of the fuel lines. None of the lines are blocked.

The fuel filter is brand new.

I have run the stock map and this pipe for over a year, without difficulties.

I put the old spark plug back in.

It seems to happen at the same throttle spot every time.

Somebody give me some direction here!!!

:confused:

wistech · #8 Post by **wistech** » Mon Oct 20, 2003 3:25 am

I remember the first time I ever rode my speed it did the same thing about 20 miles into a ride. About one minute after a warm start I hammered it at full throttle for about a half mile before it did it. It just popped and coasted to a stop. It started right back up and was good for the rest of the day and actuall never did it since . That was about 2000 miles ago. I did switch over to a number 8 plug after that. How does your plug look? If you think it may be your tps has a dead spot it is easily checked the d&m software or an ohmmeter . Download the efi manual and it will show you how. We had another guy with similar symtoms and he was very frustrated and it did turn out to be corroded ground ground off the battery. It looked good and was tight but needed to be cleaned . It seemed engine vibration at a certain speed was causing it to break contact and causing the ecm to restart.

autox7 · #9 Post by **autox7** » Mon Oct 20, 2003 3:34 am

I switched over to the #8 plug just after I broke the bike in. When I first bought the bike, it would do the same thing, and then just went away.

What would cause this?

I will re-check the ground off the battery, and I think that I am going to check all of the electrical connections under the ECU tray.

wistech · #10 Post by **wistech** » Mon Oct 20, 2003 4:26 am

I just checked my quad and the electrical diagram and found there should be 2 smaller ground wire eyelets besides the big battery cable on the lower right side of the radiator bracket. There are also 2 other eyelets onthe computer harness that I think may be under the computer tray but I dont recall removing them when I pulled my engine for the updates.
I work on a electonic diesel engines and some times I find the seals missing on the electrical plugs for sensors or injectors. This causes intermittant shorts between the low voltage wires when water gets in them and they will work fine when dry but cause problems when wet. There is a service bulliten on the fuel return line to the tank that will over presurize the fuel system and foul the plug if its kinked or not fully plugged into the tank fitting. Please bear with us if we sound repetative but the simple things must be done first before we go into deep diagnostics. If this started after engine removal then its a good bet its something simple.

Cannondaleriders

Cutting out/backfiring

Cutting out/backfiring

richen it up?