www.iFourWinns.com
https://smwebhead.com/phpBB3/

Engine Surge on Rebuilt Engine
https://smwebhead.com/phpBB3/viewtopic.php?f=11&t=23880		 Page 1 of 1
Author:  mark1190 [ Tue May 06, 2025 10:58 am ]
Post subject:  Engine Surge on Rebuilt Engine
Just when I thought I was in the clear -- the newly rebuilt engine on my:

Four Winns 1996 Sundowner 205
5.0fi/SX engine (Volvo Penta)

...is surging at idle. I am 7 hours (of 10) into breaking in the new engine. Everything was going well until hour number 6 when, at idle (600rpm) it sputters a bit, then catches again and surges up to about 1100rpm and settles down again. This happens about every 90 seconds. If I ask for power at the wrong time (coming out of the hole) and it coincides with that sputter, the whole boat lurches forward for a second, then catches fire again and takes off. Only happened once. I do NOT get any flutter or loss of power when we are underway, even at 2,000 rpm trolling. Just when idling.

In addition, the engine was difficult to start after warm up. It would start then stop. On the fourth try I turned and held the key on a little longer and it started. In fact, it was after this episode that the idle surge thing started.

Fuel related? (I used 87 octane when I recently filled it after the first 5 hours of break-in.)(Should I use a higher octane?)(Marine fuel not avail) It's ironic since the fuel we burned the first 5 hours was probably 2-years old (but treated every year).
Engine computer related?

Odd thing to have happen. Outside of that issue, the engine while underway has been great. Like the boat is new again. Really fun. (Except for this weird hiccup)

Thanks for reading (and commenting if you have any suggestions)

Mark
Author:  LouC [ Sat May 10, 2025 8:23 am ]
Post subject:  Re: Engine Surge on Rebuilt Engine
This is a Ford engine correct? I would check for vacuum leaks, and verify that the idle air control valve (if it has one) is working properly.
Author:  mark1190 [ Thu Jun 12, 2025 2:15 pm ]
Post subject:  Re: Engine Surge on Rebuilt Engine
So...I filled the tank with about 20 gallons of PREMIUM gas (mixed in with the remaining 15 gallons of year-old "regular" fuel that was in the tank already) Took it out for the last four hours of its break-in period and the idle problem only surfaced once. And the engine turned over right away when I turned the key to restart it. Idle for the trip was 99.9% normal. In fact, the engine behaved exceptionally well. My mechanic shook his "no" when I asked if the higher octane fuel might have made the difference. "The onboard computer compensates for that." It's in the shop now for break-in oil change and they will check for idle issue - which, for the last four hours, anyway, is almost moot. Other than that, the boat runs like it did when we first bought it.
Page 1 of 1 All times are UTC - 6 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/