93 2.5 EFI 260 w/unwanted 4000 RPM limit

[2scoops]

Motor idles and planes well but will not turn over 4000 RPM under load. Doesnt spit, Sputter or back fire, It just turns 4K wether the throttle is one quarter down, All the way down, or anything in between.

[Markus]

Could be a bad high-speed winding on the stator. Could also be insufficient fuel delivery. Could also be some other ignition problem.

[Fish]

does your butterfly open all the way when you give it full acceleration? Try a smaller prop, if it still yields the same rpm then probably not a fuel problem and more likely something electrical. BTW, is your battery fully charged?

[2scoops]

Thanks for the help so far, Batt. is fully charged, Will a stator for a 97 2.5 EFI 260 work on the 93 motor. (I have a new one already) If it was fuel related such as insufficient supply wouldnt it try to surge or lay down? The butterfly opens fully.

[Jay Smith]

The stators are interchangable... Check fuel filters also !

[Markus]

Do a plug chop with fresh plugs at 4000 rpm WOT and see if any plugs look different and if they are too wet or too dry.

[150aintenuff]

brett, is it running on all 6 up to hat point and it falls totally flat at 4000 or doe it act like its hitting a limmiter... could a failing switchbox be causing it to drop Cyl???

[2scoops]

I will try everything this weekend, weather permitting. Nick, It seems like it is running smoothly on all 6. You would swear that the butterfly is just cracked. I have a spare set of switch boxes for my 97 260, I will try those also if they are the same. The 93 has an analog ecu and the 97 has a digital if that makes a difference, I have a spare digital ecu as well. I havent compared the plug on the two is that a simple swap as well?

[Markus]

Swapping to a digital ECU requires that you change the size of the fitting of the hose on the air horn, or something like that - My memory fails as to the details.

Bill Gohr has posted on that topic several times.

Try the search function if no-one chimes in and gives you the story!

[boatnutz]

you had better quit screwing around with all these toys or you'll never get that shop done.

[150aintenuff]

good luck, and twllus what you find out.....

[2scoops]

Hey nutz, Arent you supposed to be at work right now? (Slacker) Nick this boat might just have your name on it, 21 Kevlar Liberator with the aforementioned 93 2.5 on it. Thanks for the help guys if the sideways rain and 50 mph gusts quit i may be able to try some of this stuff out.

[boatnutz]

rain shmain and gusts will just make it go faster, f#@k work, lets roll !!

see ya, Bill

[150aintenuff]

Hey nutz, Arent you supposed to be at work right now? (Slacker) Nick this boat might just have your name on it, 21 Kevlar Liberator with the aforementioned 93 2.5 on it. Thanks for the help guys if the sideways rain and 50 mph gusts quit i may be able to try some of this stuff out.



If I hadnt just bought a hydrostream Valero I mighttake you up on it.... at least it wasnt your STV that is having the issues..


RAINGEAR..... you whimp....... just go boating WHO CARES...

[2scoops]

Thanks for your help guys. All electricals tested fine. Cleaned all ignition grounds and went out. Worked for awhile and then quit again. It turned out to be the ground between the ecu bracket and the ecu. I guess i should have mentioned that when i first went to start it i had to prime it through the butterfly to get it going, then it started O.K. the next couple of times then went back to manual prime again. Kind of makes sense now.

[150aintenuff]

THAT WOULD DO IT...... wouldnt it..... figures it would be sumthin simple...