Engine Shutdown Problem

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CapeMay Grady Marlin

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I have a 2001 Marlin with 2001 Yamaha OX66 250's. I am religious in keeping additive in my tanks and replacing fuel filters even the VCT filters under the injector pump. All of suddent and of course in th emiddle of striper season I started having my stbd engine shutdown for no apparent reason independent of the speed. I tried to run full throttle and lost both engines.

I've never had a problem with gas and I always keep my tanks topped off. I ran both engines on a small 6 gallon tank and they run fine. Could I have a problem somewhere between the pickup tube and the connection to the engine? I used 6 gallons from both my main and aux tank so I really dont think itsa gas issue and I did replaed all the filters again and no luck?

This is an amazing boat and I want the 36' version if anyone knows of a good deal out there by the way!
 
CapeMay Grady Marlin said:
I have a 2001 Marlin with 2001 Yamaha OX66 250's. I am religious in keeping additive in my tanks and replacing fuel filters even the VCT filters under the injector pump. All of suddent and of course in th emiddle of striper season I started having my stbd engine shutdown for no apparent reason independent of the speed. I tried to run full throttle and lost both engines.

I've never had a problem with gas and I always keep my tanks topped off. I ran both engines on a small 6 gallon tank and they run fine. Could I have a problem somewhere between the pickup tube and the connection to the engine? I used 6 gallons from both my main and aux tank so I really dont think itsa gas issue and I did replaed all the filters again and no luck?

This is an amazing boat and I want the 36' version if anyone knows of a good deal out there by the way!
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Since both motors are affected, the more likely cause is a blocked/obstructed fuel tank vent. Try running with the fuel filler cap off and see if the issues goes away. If so, there is a vent problem.

If the problem happens at speed and only when the bow raises up, you might have water in the tank. At rest the level is lower than the pickup but when the bow rises,the water flos aft and rises higher than the pickup tubes. If you run at speed but trim the bow down and don't let it rise, you should run OK.
Try the fuel cap first.
 
Believe he said it was the stb engine only. Think you got bad low pressure fuel pumps. And...you probably have primer pumps so you can't use the primer ball trick to diagnose the problem. The only way to tell for sure is to unbolt the LP pumps, keeping the lines connected. Have someone activate the primer pump and see if fuel leaks out the little holes on the back of the fuel pumps. Be careful not to mess up the gaskets. Yea, PIA job you have to remove the VST to get to the top pump. The 3.1 litre engines are hard on lp pumps and if you haven't replaced them in 3-years now's a good opportunity.

Now, the Marlin is the big sister to the Sailfish. What is the 36' big brother to the Marlin??

Yea, they're catching the big fat stripers here in the bay. Just pulled my boat yesterday and missing out.
 
Tucker said:
Believe he said it was the stb engine only. Think you got bad low pressure fuel pumps. And...you probably have primer pumps so you can't use the primer ball trick to diagnose the problem. The only way to tell for sure is to unbolt the LP pumps, keeping the lines connected. Have someone activate the primer pump and see if fuel leaks out the little holes on the back of the fuel pumps. Be careful not to mess up the gaskets. Yea, PIA job you have to remove the VST to get to the top pump. The 3.1 litre engines are hard on lp pumps and if you haven't replaced them in 3-years now's a good opportunity.

Now, the Marlin is the big sister to the Sailfish. What is the 36' big brother to the Marlin??

Yea, they're catching the big fat stripers here in the bay. Just pulled my boat yesterday and missing out.
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He said he "tried to run at full throttle and lost both engines"
Probably not lp pumps
 
I"M also from Cape May,what marina are you dock at ? I have a Gulfstream with a F225 and have been using Cape Harbor for general maintenance.But several people have told me the mechanic at Pier 47 is the best around.I can't speak for experience about Pier 47, but would be willing to give them a shot if I had a Yahama related problem.

Thank you Mike
 
I"M also from Cape May,what marina are you dock at ? I have a Gulfstream with a F225 and have been using Cape Harbor for general maintenance.But several people have told me the mechanic at Pier 47 is the best around.I can't speak for experience about Pier 47, but would be willing to give them a shot if I had a Yahama related problem.

Thank you Mike
 
I keep her at Cape May Marine. They had an amazing mechanic but he left for Avalon and they guy thye replaced him with desnt give me the warm fuzzy so far. I have been really lucky with this boat this is the is the first real challenge I have had other than little stuff I've fixed myself. I've been holding off repowering because Id like to sell this and move up to a 36 Grady Express if I can fine one thats a good deal.
 
Were neighbors I also keep my boat at Cape May Marine. Are you the Marlin on C dock? I have Rich's cell number if you want it.Ihave considered upgrading to the Marlin but would like to talk to someone that owns one.Please call me on my cell phone (609) 408 3431

Thank you Mike
 
Yes that is my Marlin on C-Dock. Would really like to meet you and also if you have Rich''s cell that would be great and I will call you.

After further trouble shooting the Marina called a Yahmaha mechanic who is going to run the computer on both engines this Thursday. His inital gut feeling is my problem is most likely in one of three areas:
- Bad O2 sensors
- He wants to check the fuel pressure may be a weak fuel pump but not likely on both
- fuel restriction in th epickup tubes
- vapor screen issue

Anyway I will let you know what happens. Initally every one felt the engines were not the problem and replacing the VCT filters did make an improvemet as the stbd engine now reached 4600 before it quits abnd the port engine is good to 5000 before it shutsdown. I never run this high but it is indicative that a problem is sitting there and I dont want to get to the canyon in bad weather and figure this out. I never realized how much of a load the boat is on a single engine until I found out the hard way. Still better than my old boat with only one engine but I was surprised how much a 30 footer needs both engines.
 
Be smart and get a fuel sample before you drive yourself crazy and spend a bunch of money. You could have easily picked up un-wanted water in your fuel just by buying it. That's what happened to me and I ended up COMPLETELY draining the tanks and ALL the fuel lines. You can get a sample easily by letting the boat seet for a day ---disconnecting the fuel line at the engine and having someone hit the primer switch. Pump the fuel in to a clear container and see if you get any water. Also dump you filter(s) in to a clear container and check for same. This will at least give you a good starting point and NOT spend a bunch of money doing it. There is a lot of "Junk" fuel at the docks these days and most marinas aren't going to "eat" the cost of cleanig thier tanks with the season "over".
 
STATUS UPDATE:

Well after 3-days of troubleshooting including a certified Yahmaha tech they finally found out what the problem. For the OX-66 each two of the the six cylinders has a gas lift pump. Just so happens the cylinders 1 & 2 for my stbd engine was failing and the lift pump for the # 3 & 4 cylinders on my port engine was failing. We were able to run the engines full throttle for a couple of miles with nit even a hesitation. Also at idle since I bought the boat used the engines would shake an didle kind of rough even after the spring tuneup and not they barley vibrate and even sound different underway.

Wanted to share this with you all as this is going to end up costing me and Im not even sure how much three days of labor and parts will be but I can only imagine but at least now I know its fixed.

Steve in Cape May, NJ :praise
 
I have to admit that I am confused ( not an unusual occurrence) about the fix. My understanding is that that model SX250 has 3 vacuum operated low pressure pumps. All 3 outputs connect to the same fuel line. That line feeds the VST pump which supplies fuel to a common fuel injector rail. I can not find a reference for an electric lift pump in the service manual. A problem with an LP pump should affect all cylinders not just 2. The same goes for the high pressure electric (VST) pump. What am I missing?
 
The 3.1 litre's only run on 4-cyl up to about 1800 RPM hence the rough idle. This is just more reinforcement about how the big 6 cyls are hard LP fuel pumps. Guess that's why they have to put 3-on 'em. I'm convinced that trying to go over 3-years on a set is a roll of the dice. Hear too many stories about torn diaghrams.
 
Tucker said:
The 3.1 litre's only run on 4-cyl up to about 1800 RPM hence the rough idle. This is just more reinforcement about how the big 6 cyls are hard LP fuel pumps. Guess that's why they have to put 3-on 'em. I'm convinced that trying to go over 3-years on a set is a roll of the dice. Hear too many stories about torn diaghrams.
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True but what does that have to do with the mechanic's explanation of the problem???
 
True but what does that have to do with the mechanic's explanation of the problem???[/quote]

Not much, just an observation. Think there was a lose in interpretation or something because it didn't make any sense to me. Believe the pumps are run by crankcase vacuum, nothing to do with any individual cylinders. Don't think you're missing anything...
 
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