loss of rpm

[RossM]

Originally posted by Gav
no power loss at WOT, but my theory is whenever at idle the fuel is pouring into the airbox, when it fills to the lower carbs it floods as you try and increase revs? then clears once excess has been dragged through?

does the engine have a bleed system on it?
the 300 promax has a series of pipes either side of the front half where the reeds are, at low speed the unburnt fuel sits just in the front half just after the reeds then the bleed system removes it and puts back to the canister to be pumped back into the engine when required.

[Gav]

Originally posted by PuppiesBalls
does the engine have a bleed system on it?
th

no idea?

[JamesM]

Originally posted by scottyboy
I would have thought a reed valve fault would be there all the time to? If its the float level wrong it would cause it to do it at idle but not w.o.t! Unless the float level is set to low then it would lose power at w.o.t!

Are we talking about Gavs motor spitting fuel back out of the mouth of the carb at idle?

[RossM]

Originally posted by Gav
no idea?

well if it oil's up at idle i guess not

[Gav]

Originally posted by Johnny Boat Dude
Are we talking about Gavs motor spitting fuel back out of the mouth of the carb at idle?

yep

[Dan]

Originally posted by scottyboy
Dan,

Does it rev fine out of gear and when you put it in gear it dies?

Sort of, but up until the other day it was only intermitent fault. It doesnt just die whern I put it into gear infact I was flying along the other night then it just dies right down

[RossM]

i would say get new reeds, but if its spitting the fuel back out its saving it from oiling up. if you got new reeds it may oil up quicker.

[RossM]

Originally posted by Dan
Sort of, but up until the other day it was only intermitent fault. It doesnt just die whern I put it into gear infact I was flying along the other night then it just dies right down

I think its your stator deteriating.
also, like a coil thats on its last legs, it will sometimes give a (weak) spark but when its been running for a while and got hot it can sometimes completely fail.

[JamesM]

Dan this thread has got to be worth keeping a beedy eye on!!!

http://forums.screamandfly.com/forum...d.php?t=107128

[Dan]

Where thr **** is the rectifier on my engine, it would seem that I`ve been looking at the starter solinoid!

[RossM]

i was going to say make sure ur not looking at the solenoid!!

[Dan]

Originally posted by PuppiesBalls
i was going to say make sure ur not looking at the solenoid!!

So where do I look then (from the starter solinoid?)

[RossM]

have you got a pic of your engine ?
what model is it?

[Dan]

Originally posted by PuppiesBalls
have you got a pic of your engine ?
what model is it?

No pics, its a blackmax earlt nighties ish.

[RossM]

can you p.m me the engine number and ill get a pic for ya and find out where your reg is

[Dan]

Originally posted by PuppiesBalls
can you p.m me the engine number and ill get a pic for ya and find out where your reg is

Its p**sing down with rain and I dont want to get wet tonight. I`ll do it 2mo, any idea where I should be looking tho?

[RossM]

http://www.mercruiserparts.com/Show_...TAGE+REGULATOR
if your enging looks like that then its the big thing aka number 5. reconise any of that?

[RossM]

or, http://www.mercruiserparts.com/Show_...TAGE+REGULATOR
number 7

[JamesM]

Originally posted by Dan
So where do I look then (from the starter solinoid?)

Its just to the left of the starter solenoid above the switch boxes on mine.

[Matt]

If it's the stator, then it'll be either the high or low speed stator.
The high speed stator cuts in at, I think about 2500 rpm. So if you can't get it over 2500 rpm, that's a good indicator of it being the stator. You can also put an AC voltemeter on the stator outputs and compare left & right, high and low speed readings. You'll likely find one particulary low compared to the others.

You can also check the output from the switchboxes to the coils - but you do need a DVA adaptor for this. I vaguely remember jw posting a circuit of how to make one once.

Coils are a classic weak component, and notoriously difficult to conclusively identify without substitiuting them for known good replacements, and can be very intermittent.

I think the rectifier stuff is bollocks, it's a different winding on the stator, and you can quite happily run the motor without the rectifier even installed. The only "risk"is if the rectifier fails and short circuits it can fry the stator, but that's rarer, usually it just swithes off, permenantly

If the fuel pump is weak, the top carbs empty first, but the lower ones are still full & pulling. If you back off a bit for 15s or so and punch it again and it picks up, this could be an indicator towards this.

Assuming the fuel system is in generally good condition (no hoses leaking etc), it's IMVHO, most likely electrical.