225 merc efi run away throttle

[perryk]

1998 225 merc efi that has been in the yard all winter. I took it out yesterday, ran 5 miles or so, when I powered down the sbd. main sputtered and coughed for a sec at idle. I pulled it into neutral and the rpm's instantly pegged against the rev limiter. Has anyone ever seen anything like this or have any ideas?<br /><br />thanks

 

[rodbolt]

Re: 225 merc efi run away throttle

sounds like either a cable issue or a TPS issue, something gave it extra fuel and timing.<br /> with no load it does not take a lot and the air bypass holes can pass enough to rev fairly high with no load.

 

[Don S]

Re: 225 merc efi run away throttle

You need to post your question over on the Merc outboard forum, this forum is for I/O's.

 

[perryk]

Re: 225 merc efi run away throttle

Thanks Ron, I'm going to trouble shoot the TPS today just need to build a test harness.<br /><br />Don, thanks as well, I did poste under outboards as well, I was doubling up to cover more people, no answers from the outboard list as of yet.

 

[wvit100]

Re: 225 merc efi run away throttle

An outboard in nuetral can run away if it is given too much gas. If your motor was bogging and you put it in nuetral it could easily overrev and not drop back down. All of the owners manuals warn you about this happening.

 

[perryk]

Re: 225 merc efi run away throttle

1998 225 merc efi that has been in the yard all winter. I took it out yesterday, ran 5 miles or so, when I powered down the sbd. main sputtered and coughed for a sec at idle. I pulled it into neutral and the rpm's instantly pegged against the rev limiter. Has anyone ever seen anything like this or have any ideas?<br /><br />thanks

 

[perryk]

Re: 225 merc efi run away throttle

While trouble shooting the TPS I found one of the EFI bleed hoses had split and come loose from the hose barb. Since it was out of position it was obstructing the butterfly on the throttle body preventing it from closing 100%. Snipped the split portion off, reattached it, fired it up and it has run fine since. Thanks for all the input.