1995 Four Winns 278 Vista - Twin Cobra OMC 5.0L

[dangerroth]

Can someone please help me with this nagging issue!?!?

I have a 1995 Four Winns Vista with twin Cobra OMC 5.0L V8 fuel injection. The issue started five years ago. The boat planes at 3200RPM but periodically the port engine will drop down to 2000RPM and bounce between 2000RPM and 2500RPM. The sound has been described by one mechanic as "bouncing off the limiter." The issue happens in both forward and neutral. When the issue started it would happen maybe once every two hours of use. Over time the intervals shortened to once every five minuets so I took it to a mechanic. This was three years ago. The mechanic convinced me that it was an engine issue and the engine needed to be rebuilt. I bit the bullet and had the engine rebuilt with a one year warranty. The boat ran great all of 2015 but didn't get used much. At the start of 2016, just over one year after the rebuild, the issue started happening again. Towards the end of last year it was happening almost constantly. Now it's the start of a new season and this is keeping me from using the boat. I have replaced the fuel filters, fuel pump, and had the throttle position sensor replaced. It was hooked up to a computer last year and didn't show any error codes. The starboard engine runs fine. The port engine sounds great when it starts up and runs fine at low RPM. I had a independent mechanic look at it last week and he suggested replacing the shifting cable. He said the "shifting cable is hanging up" but my normal mechanic is skeptical that will fix anything. No one can tell me what the heck is going on! There are links below to some videos I took that show the problem. We keep the boat at a marina in Toledo, OH and store at the marina in winter. We don't have a trailer so there are very limited options for mechanics on the water. Any help would be greatly appreciated!

https://www.youtube.com/watch?v=LnSUtRJhIHQ
https://www.youtube.com/watch?v=wfCXNOOl3Us
https://www.youtube.com/watch?v=TVLFXOwWzqE
https://www.youtube.com/watch?v=YUwS7ImQanM

 

[HT32BSX115]

I have a 1995 Four Winns Vista with twin Cobra OMC 5.0L V8 fuel injection.

Howdy,

Welcome aboard!

Well, first of all, it will help if you post your (engine) model number.

Your engine/drive combination could be any of the following and there's subtle differences...none of which may make any difference at all but it gives all of us a starting point.

50FAPHUB 1995
50FAPHUE 1995
50FACPMDA 1994
50FACPMDM 1994
50FAGPMDA 1994
50FAGPMDM 1994

From the sound of the video, your problem sounds an awful lot like an earlier model Dog-Clutch ESA activating.

Some (or all) of the Cobra SX EFI/Electonic IGN models have a "shift-interrupt microswitch which *could* be activating in yours.

Your engine doesn't have an "ESA" as such, it's taken care of internally in the ECM when shifting (presumably) out of gear.

Your model number will help in identifying that part.

Regards,


Rick

 

[Larson220]

Hi, i have the same engine on a 1994 Larson. These engines have a feature called SLOW circuit. It is essentially a feature to prevent one from blowing an engine due to loss of oil pressure or running an engine hot- overheating. It uses two sensors to measure engine water temperature and one for oil pressure.
Do not confuse these with the sensors for the guages, they are separate. I found out about this feature when i first hit my boat and on the first run on the lake the water pump impeller went south and the engine overheated.
These engines suffer from irritating wiring connectir issues at times that can cause these various sensors to malfunction.
I will try to post a couple of images from my shop manuals that illustrate the wiring for these switches, which is essentially what they are. I hope you can find a hood mechanic that has good electrical knowledge, because the manjority of repairs related to these engines are electrical. The engine computer will not store codes for the slow system, it is a separate system that when activated due to an overheated engine or loss of oil pressure, will limit the engine to 2000 to about 2800 rpms. The engine will feel as if it is hitting a rev limiter, which is what the engine computer does to prevent a catastrophic engine destruction.

 

[Larson220]

I have not uploaded photos before and i tried but i kept getting an error message. Send me a PM and i eill email you the images of the workshop manual. Pnit them and take them to your mechanic and they should be able to figure it out. Good luck

 

[Larson220]

Use this link to the Manual from PCM, same engine same system and a very good manual about the electrical parts if these engines.
https://www.correctcraftfan.com/Downloads/Pro_BOss_GT-40_Service_Manual.pdf

 

[Larson220]

See section 2A in manual from PCM

 

[Larson220]

Section 2A-10 in the manual. That page explains the Slow system in detail. This manual will explain all the complex electrical areas of these engines.
These engines were built and marinized by ford and sold to various companies, OMC, Volvo Penta, pleasurecraft marine- PCM. They are all the same engine from that era. The electrical and fuel injection system are all the same. Good luck

 

[Larson220]

I watched your your videos. Your engine is most definitely suffering from a malfunction of the SLOW safety system. I would go back to the mechanic that told you that the engine needed to be replaced, or the one that replaced the engine and have them fix it. It really is not a real difficult repair. It probably is a bad electrical connector or wire. The actual sensors for the Slow system rarely go bad.