150cc ASW Zircon engine keeps dying on the trail. Ideas anyone?

[doberman1]

Ok, so I'll give you some background first.

ASW Zircon. Stock except for high flow filter.
Sat unused for 2 years
clear fuel lines, vacuum style petcock works great.
new filter
brand new 24mm carb
new plug
fresh gas
No vacuum leak that I can find.

Here is my problem. The buggy starts and idles fine. The buggy does great on the top end and all points in between. When I am driving on the trails everything is good until I hit the brakes and lock up the rear wheels. When I hit the brakes, 9 times out of 10 the buggy will stall and die. It won't start easily again unless I give it a small bit of throttle. Then it starts and accelerates fine. Thought maybe the 20 dollar carb was junk, so I rebuilt the tamper proof stocker. buggy still dies. I have tried all kinds of different idle speed settings. The buggy did not do this prior to the 2 years of inactivity. Any ideas? (Please tell me I need an A9 cam, big bore kit, higher compression, ported big valve head and aftermarket exhaust,bigger carb, a turbo, and nitrous. All running on methanol LOL...! just kidding around. For now)

[jmansracerocket]

It's a possibility that the vacuum petcock could be the culprit. When ur on the gas and slam on the brakes you cut the vacuum which causes a fuel drop. Your also saying it won't start again until you give it some gas which to me would indicate the carb isn't getting good fuel flow. Also the petcock could be clogged since you said it sat for 2 years. Also try turning the fuel mixture out maybe a little more for more fuel. Last thing to check for fuel would be the carb float level.

[doberman1]

I do have a new petcock assembly. I will try it. When I flushed the gas tank I visually inspected the petcock. But that does not mean I didn't miss something.

[doberman1]

Oh, does anyone have the spec for the float level?

[jmansracerocket]

another thing make sure your gas cap is vented.

[doberman1]

Ok, gas cap is venting correctly and new petcock did not help. Have not tried the float, but both carbs do the same thing. Gonna check the float when it cools down.

[jmansracerocket]

Did u put in a new vacuum petcock or manual ?

[doberman1]

I put in a new vacuum style. I figured the old diaphragm might be getting tired. I had a chance to run it some more. This time I scratched my head and I paid more attention to the symptoms. It does not die on smooth ground like in my front yard no matter how hard I hit the brakes (unless I slide sideways). only when it is on rough, rocky terrain. All of our trails around here are rough rocky terrain (anywhere from marble sized to fist sized), but when I accelerate up the hills I'm fine. My grades are steep enough going down hill that I just always happen to be on the brakes when it dies.There is no way the buggy would ever make it up those hills. just no traction. I idled at the top of a down hill section today, and let gravity take over. I did not touch the brake or throttle. When it started getting bumpy it died, THEN I hit the brakes because I wuz haulin ballz by then.:big grin: I think raising the float level slightly might be worth a try....Waddaya think? I'm seriously considering trying to retrofit this thing with some front brakes, too. My hubs are factory drilled in a six bolt pattern. But that's a subject for another thread. And more research before I pester you guys on this site.

[doberman1]

I did adjust idle mixture and that seemed to help some. But I had to screw it all the way in? That's odd to me......

[ckau]

I've seen this before. every time the guy slammed the brakes the buggy would die. It was a poor electrical contact in the ignition switch. the force of braking was just enough to ground out the cdi. In my experience, every time a buggy suddenly starts behaving erratic, I go to the electrics first. A point for using clear fuel lines is you can observe and confirm flow problems immediately. no guess work there.

[doberman1]

Good info. looks like I will be grabbing my VOM today and checking connections as well!

[SYCARMS]

CKAU has the right idea. It will not be the vacum fuel pump since the bowl would have to run out of fuel first.

[doberman1]

As a side note, I put clear fuel lines on right after I flushed the tank. Fuel flow is no problem. went through the buggy with my VOM. Everything checked out good except my light switch only works intermittently. I did find four wires leading from the dish to the electrical box that have abrasion damage down to bare wire on 2 wires. am going to cut and solder them in a few minutes. Spent all weekend doing lots of different things to the buggy. Welded in brackets to move the seat forward so my wife and daughter can reach the pedals. She is only 4' 11". One thing I thought of and plan to address today is that I replaced the stock airbox with aftermarket air filter and extension. If I grab the filter and wiggle it side to side briskly it kills the engine every time. The carb moves around a lot compared to the way it moves with the stock airbox in place. am going to weld up a bracket to mount filter extension tube to the frame. I checked to see if my intake manifold had a crack or a vacuum leak by shooting starting fluid around it while flexing in different positions. no leaks. So before I crack it I will mount the air filter better. It really seems like I have a severe fuel slosh problem. I am going to check connections again with VOM just to make sure. But i'll fix the abraded wires first. If you guys can think of something, no matter how obscure, please chime in! Thanks!