Okay here is a tester for you,
I have been working on my own quads for 10 years and I can't figure this one. I bought a 2004 DVX (same as a Suzuki LTZ 400) which had 10 hours on it. Looked new, started right up, ran for a few hours then started stuttering and stalling. Looked inside the carb and there was what looked like rust particles and residue. Apparently it was the original gas from new!

So, I have cleaned and rebuilt the carb. petcock and gas tank. It still runs and dies. I installed a fuel filter between the petcock and the carb and can see the fuel stop flowing. I switch it to prime, the bowl fills again, it runs until the fuel stops flowing then same thing. It is driving me crazy, does anyone have an idea why the fuel stops flowing to the carb?

Suggestions appreciated.

 

Something is clogging that petcock OR perhaps your tank vent is clogged

 

check your float height.

 

How do you set the carb float height? Where should it be ideally? I just rebuilt the carb and used the new float plunger that came with the rebuild kit.

 

I had tank venting problems with another quad so that was one of the first things I checked. Thanx anyway!

 

One other thing... it will run fine but then if it hits bumps or goes on a steep downhill it acts up again until it gets on flat ground. But it still happens all the time argh....

 

Fair enough. from your post, it sounds as though you actually end up with no fuel in the filter at some point until switching the petcock to "prime." If that is the case, I would drain the tank then clean it and the petcock one more time. Sounds like it might have a dirty tank clogging the petcock intermittently.

 

On that type of carb and petcock, fuel will only flow in the "on" position if there is vacuum on the line from carb,maybe that is plugged. Prime position bypasses that, and lets fuel flow directly from the tank. Dont know why Suzuki made it like that,maybe as a safety thing,to only draw fuel when the motor is acually running.

 

I have flushed the tank 4 times with Acetone, removed the petcock and inspected the tank. It is clean as a whistle. I disassembled the petcock and thoroughly cleaned it as well ( it was very dirty). I think i might have figured it out. I will be taking it for a test ride on thursday and will report back. When I cleaned the carb previously, I dropped the float and it fell apart. I think I might have put the plunger spring on backwards (180) when I reassembled it which made the spring susceptible to catching thereby keeping the plunger in the closed position when it bumped around. I flipped it the other way last night and it makes it harder for the spring to slip and catch on the end of the float piece. Let's hope that is it!

Will report back.

 

hey i one time had a weed seed floating around the carb and it would clog the main jet in certain situations , it would stick to differant parts of the carb when u would drain it so u wouldn't see it .just a thought .