Gy6 idles at low speed and then dies too

[nacra533]

Just like the previous post, mine cranks, ides for about 15 sec and dies. It dies if I give it any gas/accelerator at all.

I just bought it used, so have no history on it. Baja reaction 150. Dogs ate the wiring, so i rewired the bad spots. Almost positive everything is correct because i was able to match all wire ends ( ex yellow to yellow, green to green, etc)It didn't even fire when I got it.

I pulled the carb and cleaned very well. The float looked a little off, too angled but i left it alone because I didn't know the setting. Put it back on and it fired right up and idled. I went to bed.

Next day, I cranked it again and it idles for about 15-30 seconds and then died. Keeps cranking back up but if I give it gas, it bogs down and dies immediately. Also, after many cranks, it idles less and less, maybe only a few seconds after it warms up.

I pulled the carb again cleaned again, adjusted the float to parallel to the body because I saw that on a forum somewhere. No change in problem.

Help please. It seems too rich on the surface, but could be a cdi, choke, or another electrical problem. I've been over wiring and can't see anything apparently out of whack.

Problem exists with air box hooked up and with air box removed.

[nacra533]

Been following the other thread.

New plug, gapped. Spark looks good I guess.

Still think its too rich. Any application of very slight throttle immediately kills the engine. Also, after 4-5 cranks, engine runs less time each time.

Also, Adjusted air mixture screw and idle screw, no significant change. Engine cold during this. I'm in GA, so cold is relative. Outside temps 55 degrees

Should the pilot jet and hi speed jet be seated then backed out some turns??? In my kid's Tecumseh engine kart and my outboard boat engine, this is not the case, so I don't think this is the case.

I did notice the diaphragm (rubber) on the opposite side of the choke of the choke is deformed (possibly a primer). I was able to seat it(carefully) to get it aligned properly. Could this be the problem??

[metalstudman1]

Jets in the carb should be seated gently but firm. Can you post a pic of your carb? the diaphram you speak of is on the outside of the carb? sounds like you have a 30mm carb with the accelerator pump.

[nacra533]

That sounds right. Can't post a pic right now, but it's the carb in this video. At about 1:30, he points it out.

http://www.youtube.com/watch?v=XuMH_ILOQmo&sns=em

http://www.youtube.com/watch?v=XuMH_...e_gdata_player

[metalstudman1]

Wow! that's a terrible vid - he says the intake (part you straightened up & reset) for the manifold vacuum line goes to ventilation!!! It hooks to the intake outlet to get vacuum to move the sllde diaphram (under the top cap).He also says the choke (FEV) is variable- not true- it works one way only-it starts out (cold) retracted (large fuel orfice,small airway) & then extends as the motor/FEV heats up to expose the normal fuel inlet at the needle jet.This is done by providing voltage to the FEV from a resistor block (usually 1 or 2 tan porcelin block/blocks), the voltage heats it up and makes it extend, once extended it won't retract till it's "cold" again. If the FEV doesn't extend (due to being burnt out) too much fuel not enough air to feed engine properly.
It's possible that the vacuum inlet diaphram could have been causing your issues- if it wasn't functioning then the large diaphram (throttle slide) wouldn't move correctly(pulling the slide up to meter more fuel/air mixture @ 1/4+ throttle to WOT.
I'm going to say the FEV (fuel enrichment valve/choke) isn't working.remove the 2 screws and pull it out. Note the amount of the plunger exposed, turn on the ignition (or apply a power source), wait a few minutes and check for the plunger to have extended about a 1/4". If no change in the plunger- check wires going to the FEV,use a test light or volt meter to verify voltage is present.If voltage checks out then FEV is bad. If no voltage, keep following wires and checking connections to the ignition.

[nacra533]

Spent some time on it today. I have a service manual for a baja crossfire 150, mine is the reaction. I am pretty sure the engines are the same or close enough.

NOTE: this carb does not sit horizontal, it angles backwards. The air intake is lower than the butterfly and intake manifold. See notes on float below.

I thoroughly verified all wiring was correct. Started some electrical checks. I am very suspect of the fuel air mix.

Deni pd24j carb
Pilot jet 35
Hi speed jet 77?? It looked like an 11, 17, or 77, couldn't tell

-Choke FEV is good. 11mm with power and 14 mm 5 minutes later. Book says this is proper.
-Coil reads .6 ohms. Book says 0-1 is good.
-Plug is new. I don't suspect the plug b/c I have good spark and it idles pretty good at first.
-Haven't checked valves yet.
- the diaphragm mentioned previously (side of carb) looked much better when I pulled it. I must have gotten carb cleaner on it last time causing the deformed look. It was nice and round this time. I am no longer suspecting this as a culprit.

I pulled the carb again today, cleaned again, checked everything. I adjusted the float again away from the way the crossfire manual shows to a little more diagonal, thinking maybe there is not enough fuel in the bowl to do anything more than idle. It seemed a little better. I was able to nurse it gently above idle to the point where the clutch was starting to engage.

With the air box off, I can see a backfire in the carb. This occurs occasionally when idling and when I apply accelerator (opening the butterfly.) i assume a float height can cause this (too high). Could this also indicate an intake valve not seating?

I have a new plasma cutter. If I don't get this fixed soon, I may have some fun cutting this thing into pieces.

[metalstudman1]

Do the valve adjustment!!!!!

[satoys]

Nacra533 - I just went out to do a valve adjustment on a engine that won't start, it was easy - and I don't know what I'm doing. Watched this utube last night - even easier than the video showed. http://www.youtube.com/watch?v=s0K-ytyjOFg

[nacra533]

Originally Posted by satoys

Nacra533 - I just went out to do a valve adjustment on a engine that won't start, it was easy - and I don't know what I'm doing. Watched this utube last night - even easier than the video showed. http://www.youtube.com/watch?v=s0K-ytyjOFg

Thanks. I am now thinking the intake manifold may be leaking. The valve adjustment is next on the list. Thanks for the link!

[satoys]

Look inside the intake manifold first, mine is cracked all over the place, looked in side, it is solid metal, so guess the outside rubber does not matter. Saw somewhere that if you spray starter fluid at the intake while running, you will hear it rev if leaking. Search first, my memory is sometimes faulty !

[metalstudman1]

satoys - you're correct, I use carb cleaner (no as explosive!)

[SYCARMS]

I would first check the valve adjustment as well as compression, the compression test will tell you if you have compression 130 psi minimum. Don't care what you do for if valves are badly misadjusted or compression is low it will not run correctly. The diaphram on the right side is the air bleed valve, if that diaphram is ruptured or has a pin hole in it your buggy will not want to run. Also note that some also have a small o-ring under the cover and if bad will cause a vacume leak.



TOM

[nacra533]

Dont have a compression tester. Buggy has pretty low hours on it.

Im doing the valve adjustment today. Gonna start with .004.

I definitely have a leaking intake manifold. Ran like a champ when I sprayed a little carb cleaner on it. I'll replace it when I can get the part and post results.

Thanks all for the help so far.

[nacra533]

Valve adjustment made a world of difference. It now runs.

Really tightened intake manifold bolts and gasket screw. Not sure if that stopped leak. Was able to drive around the yard a little. I don't have seats, so didn't go far.

Now on to the frozen brakes.

[satoys]

Originally Posted by nacra533

Valve adjustment made a world of difference. It now runs.

Really tightened intake manifold bolts and gasket screw. Not sure if that stopped leak. Was able to drive around the yard a little. I don't have seats, so didn't go far.

Now on to the frozen brakes.

Now go read the many good threads on the brakes, bleeding, etc. My main problem was frozen caliper pistons. Here is what I learned http://www.buggymasters.com/forum/showthread.php?t=2512