Carbs not doing anything??

[tengals123]

Here we go. At max spark advace im pulling 1800pms loaded. when i open to WOT and the carbs open up fully, im gaining 50 Rpms extra, instead of 3500 RPMS extra.<br /><br />1.Butterflies are fully open<br />2.Pumping the bulb floods motor<br />3.engine is timed at 4deg btdc and max at 35deg.<br />4. seems to idle fine.<br />5. spark has been tested cold crank at idle and wot with a timing light, it has spark.<br /><br />This is really annoying me now.<br />Please anyone have any idea's?<br /><br />cheers

 

[Dunaruna]

Re: Carbs not doing anything??

I know nothing about merc carbs but if I relate your problem to a car - you've got the wrong (or blocked) main jet. Is it possible you somehow switched jets during the rebuild?

 

[tengals123]

Re: Carbs not doing anything??

No chance of mixing the jets up because evrything was labled correctly.<br />I can check my main jets tonight, do you think it/they maybe blocked. I just rebuilt all the carbs?? I'll check.<br /><br />Would this result in my symptoms, ie, not getting the rpm's I should be?<br /><br />cheers

 

[Dunaruna]

Re: Carbs not doing anything??

just trying to help you 'work' the problem. I repeat, I know nothing about merc 2stroke carbs.<br /><br />Take a breath, have a cuppa. <br /><br />You need air, petrol and spark - in a correctly timed enviroment. One of those is not playing ball. If it were me, I'd start with the last thing I touched - the carbys.<br /><br />Your butterflys are fully open - that takes care of the air. (your cowling isn't fouling the throats, is it?)<br /><br />You have checked your timing 500 times - reasonable to assume that's o/k.<br /><br />Petrol???????????? A blockage either in the fuel line or the carbs.<br /><br />Aldo

 

[Dunaruna]

Re: Carbs not doing anything??

Just thinking out loud - don't these have reed valves, could they be restricted somehow? Fitted back to front or something like that?

 

[tengals123]

Re: Carbs not doing anything??

thanks for your help Aldo. Air is not a problem as all the testing has been done with the cowl off. timing is perfect. <br />yes it has reed valves, but before i rebuilt and re timed the motor ran max rpms fine and i never touched the internats of the motor.<br />So, ok that leaves me with 2 things.<br />Fuel delivery (carbs), remember pumping the bulb while running floods the motor.<br />Or spark/ignition??<br />Has to be one or the other.<br /><br /><br />cheers

 

[achris]

Re: Carbs not doing anything??

Can we please be informed of the horsepower and year/serial number of the engine we are trying to help with? <br /><br />I could give you a whole load of information about all sorts of things to check, but if it's not for the right engine, it's useless. <br /><br />Chris...............

 

[tengals123]

Re: Carbs not doing anything??

sorry bout that,<br />100hp merc. 1000<br />1968<br /><br />cheers

 

[achris]

Re: Carbs not doing anything??

Just found out that this is a continuation of another thread. Please don't do this, it's really confusing. Stay with the thread you started. It makes it easier on us oldies. <br /><br /> other thread

 

[tengals123]

Re: Carbs not doing anything??

no problem chris, actually this is an updated thread. <br /><br />Do you have any idea's on my problem???<br /><br /><br />cheers

 

[AMD Rules]

Re: Carbs not doing anything??

Like Dunaruna I'm just tossing out ideas.....<br /><br />Next time you're on the water testing, try running WOT and kill the motor. Its not easy removing plugs while on the water, but they may tell a story. Inspecting them later after idling back to the dock won't be as beneficial.<br /><br />Did you change any of the fuel lines, fuel pump, or bulb when you tuned your motor? Maybe they're restricting flow?<br /><br />(Still looking forward to pictures of your boat on the water)

 

[tengals123]

Re: Carbs not doing anything??

i changed lines, the pump and bulb was rebuilt last season (fine). I do notice when i first prime/pump the motor i have air in the line. But once running/sucking, there is no air in the line. I will check the plugs again tonight.<br />Someone mentioned to me about a 'high speed coil'???<br /><br /><br />cheers

 

[achris]

Re: Carbs not doing anything??

High speed stator.. Not relevant... you have a distributor. Run some clear fuel hose to the carbs, see if you have air bubbles.

 

[tengals123]

Re: Carbs not doing anything??

my fuel line is clear. As stated i have long open bubbles before i prime, but once primed and sucking i have no bubbles.<br /><br />cheers

 

[tengals123]

Re: Carbs not doing anything??

ok, im starting to think, spark and compression now.<br />I will re-check tonight and post.<br />Back to basics.<br /><br />cheers

 

[Dunaruna]

Re: Carbs not doing anything??

Once again I'm just thinking out loud - you replaced the primer bulb last season. The arrow is facing the correct way?? They have a one way valve. They'll pump but not 'retain' if fitted backwards.<br /><br />Aldo

 

[tengals123]

Re: Carbs not doing anything??

yep, arrow towards the motor, in direction of fuel flow.<br />Thanks for trying to help.<br /><br /><br />cheers

 

[Dunaruna]

Re: Carbs not doing anything??

Hey, I've got a vested interest in this puppy reaching it's potential <br /><br />BTW (and this is a genuine offer), if you want to 'wet test' and adjust stuff, and have another boat alongside for safety - it can be arranged.

 

[tengals123]

Re: Carbs not doing anything??

Thanks heaps for the offer. I did test at the National Watersport Centre last friday, but as stated could'nt get over 2400 RPMs. I was just lucky the motor ran superb at that speed that i had no problems getting back to the ramp.<br />Y'day when I water tested it was still on the trailer at Patto river boat ramp and all I could get was 1800 RPM's.<br />Go figure.<br />I'll get to bottom of it, evntually. I'm just going to get down to basics. <br />Tonight Check plugs, check spark, check compression.<br /><br />cheers

 

[tengals123]

Re: Carbs not doing anything??

well, well, well....<br />Before I go on, i'm going to post a new thread to gain opinions called 'result-blown cylinder'<br /><br />That's right 122 across 1,2,3,4,6<br />a big fat 0 on 5<br /><br />a few months ago all was fine.....<br />what to do rebuld or junk???<br /><br />cheers