Promax Falls flat at around 6000 rpm.

[whipper]

Im going to try new plugs first. Next to see if there's maybe a bad coil if the plugs don't fix it. Thinking wires, maybe a bad plug wire? Takeoff onto plane was pretty good. Would say not as snappy. Up to 60 floored up on on the pad to around 70, 25 trophy and thats all she wrote. Kinda odd feeling when your trimmed for past 70 and have to back off as holding it there was sorta surging. Not ruling out Pulse pump also. Gota work all weekend but maybe try plugs after work one day hear and keep ya posted. :]

 

[aj06bolt12r]

Always start with compression, if that checks out I would suspect fuel delivery... Going rich for some reason? Bad air temp sensor?

If its a bad coil or a bad plug one of your plugs should look different than the others when you pull them out.. Will be soaking wet with fuel from not firing.

 

[GotMyAlly]

Long shot guess here. Broken Reed?

 

[aj06bolt12r]

Broken reed is possible... Are you noticing any sputtering or sneezing at idle or acceleration? It would also spit gas back out of the intake, but that's hard to see on laser motors with their backwards facing air inlets.

 

[gmorgan]

If you have pyros, it should indicate which side is low on temp, thereby alerting you as to which side of the motor is missing.

 

[ssv1761982]

I have had bad reeds affect idle much more than top end but I'm far from an expert.

 

[John_Richied]

I would suspect fuel delivery

Are you running Canadian gas?
sorry I had to say it Whipper...

I would start simple as you said in any two-stroke spark plugs.
Fuel system: siphon fuel out of bottom of the cell and check for water and contaminants. replace fuel filter (full of water or cut open?), check pump pressure/volume, fuel cell pickup screen, injector screens and for fuel hose deterioration.

Plus you probably are working too much... take some time off ASAP.

 

[gmorgan]

Im going to try new plugs first. Next to see if there's maybe a bad coil if the plugs don't fix it. Thinking wires, maybe a bad plug wire? Takeoff onto plane was pretty good. Would say not as snappy. Up to 60 floored up on on the pad to around 70, 25 trophy and thats all she wrote. Kinda odd feeling when your trimmed for past 70 and have to back off as holding it there was sorta surging. Not ruling out Pulse pump also. Gota work all weekend but maybe try plugs after work one day hear and keep ya posted. :]

Whipper it is good to see you back. Have a nice summer.

 

[whipper]

I may have found the problem. Every bolt on the mid section and adapter plate was loose and 3 bolts missing!! Today testing saw water seeping in the back onto the pan. Maybe at higher speeds I was getting water were it didnt belong like a cylinder. haha Test again tomorrow night. red locktight this time. hmm

 

[aj06bolt12r]

I may have found the problem. Every bolt on the mid section and adapter plate was loose and 3 bolts missing!! Today testing saw water seeping in the back onto the pan. Maybe at higher speeds I was getting water were it didnt belong like a cylinder. haha Test again tomorrow night. red locktight this time. hmm

I had that happen to me on the Suwanee river run with my Promax... I had water running out of the pan and had lower water pressure than normal on the gauge... But the engine ran as normal... Here's hoping you get lucky! I guess you already did since the powerhead didn't fall off!

 

[whipper]

Tightened everything up with locktight this time and fastened my brocado acu down. When i had the cowl off i noticed the bottom rubber nut of the ACU was missing and it was flopping around. Boy oh boy ill tell ya she has been running so good for so long I got complacent on my checks!! So I tested it tonight and ran like a champ!! haha i cant belive that made it act funny at high speed. Interesting. Also very smooth!! haha the power head bolts above the mid section bolts were also loose and 2 missing?? Hmm See i have a lower cowl and havent taken it off in years. So all this stuff was going on were i couldn't see. Anyway must have been getting water from the cooling diverting up with intake or something i don't know it was a lucky guess. But rant great after i did these things. hmmm

 

[whipper]

Are you running Canadian gas?
sorry I had to say it Whipper...

I would start simple as you said in any two-stroke spark plugs.
Fuel system: siphon fuel out of bottom of the cell and check for water and contaminants. replace fuel filter (full of water or cut open?), check pump pressure/volume, fuel cell pickup screen, injector screens and for fuel hose deterioration.

Plus you probably are working too much... take some time off ASAP.

haha 94 oct Chevron with Aces. I am off for a month now and heading to the lake south for 10 days and a week at our friend on the lake hear. :] BTW i also dumped some seafoam in the gas incase an injector wasnt happy. The fuel in there is real good. lol Rebuilt pulse pump and new filter. But she still went flat at 6500 rpm. Tightened the pan and add new bolts so my mid wont fly off haha and water stays were it should and temps went down water pressure great and 7200 rpm two up and never changed just add trim. :]

 

[John_Richied]

Right on brother, glad you are up an runnin'

 

[whipper]

Right on brother, glad you are up an runnin'

Thanks so far so awesome!! Running great over 7000 rpm with my 25 trophy again. I bet water was getting blown up the exahaust at higher speeds giving me a mist near compression in a cylinder perhaps. The last couple year i was thing she was just getting tired. now as strong as ever? wow haha I changed out the midsection some years ago so I was the one who tightened those bolts. Guess I should have double checked them. That lower cowl makes it hard to just see that they were backing off. Probably started a couple years ago. Made me think its probably time for another steering bolt also. Ive seen what happens when they sheer at speed dont want that. lol

 

[RiverRat71]

Whipper, that looks like the Garden of Eden. Makes sense, if there was a boat there I guess it would be a GrandSport, lol. RR

 

[whipper]

Its a lovely place and lake. :]

 

[Keith E.]

Thanks so far so awesome!! Running great over 7000 rpm with my 25 trophy again. I bet water was getting blown up the exahaust at higher speeds giving me a mist near compression in a cylinder perhaps. The last couple year i was thing she was just getting tired. now as strong as ever? wow haha I changed out the midsection some years ago so I was the one who tightened those bolts. Guess I should have double checked them. That lower cowl makes it hard to just see that they were backing off. Probably started a couple years ago. Made me think its probably time for another steering bolt also. Ive seen what happens when they sheer at speed dont want that. lol

Glad to hear that you chased, caught & exorsized your mechanical demons. Beautiful place you have, BTW.

Keith