Carver 356 RPM issues

[cpoint]

Well update on this issue, still RPM issues continue. Replacing the rotor cap did not fix anything. I think I am going to have to learn to live with the RPM/port engine issue.

[cpoint]

Source of the post Made a bracket and installed these Racors on our 3697.

Racor (Large).jpg

Sorry, looks like I had missed this posting. So going this route, suggestion is to add 500MAM 30 micron, and leave the factory one that's on the engine? will having two filters (this 30 micron and the factory 25 micron) cause any issues with flow of fuel?

[g36]

If you talk to parker/racor they will tell you to not have 2 of the same it is not needed, the 500mam for gas should be first and then smaller filter micron from there.

[bud37]

Source of the post

Source of the post Made a bracket and installed these Racors on our 3697.

Racor (Large).jpg

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The two filters is probably not a good idea, could create suction pressure issue and possible vapor lock since you have mpi......you could simply replace the factory filter with a lower micron, or install the Racor in place of the factory, just not both.But really that level of filtration is more than enough.

[Viper]

I'm getting a little lost with the length of the thread so I don't recall what's been covered short of reading through everything again. Has anyone done a cylinder drop test, vacuum test, and ensured the ignition system isn't in service mode? Is this a MEFI application? If so, have any codes been retrieved? Has rpm been confirmed at the engine itself?

[cpoint]

Source of the post I'm getting a little lost with the length of the thread so I don't recall what's been covered short of reading through everything again. Has anyone done a cylinder drop test, vacuum test, and ensured the ignition system isn't in service mode? Is this a MEFI application? If so, have any codes been retrieved? Has rpm been confirmed at the engine itself?

Viper, Yes sorry, this is getting to be a long thread. I will stop posting to this unless I find a cure down the road. Everything has been done, all test were done by a mercruiser authorized mechanic shop. Lots of part replaced, fuel drained several times. computer readouts done, all came back clean. twice compression test, with good results. Now I just keep it at 2000 rpm, about 9 knots and its fine. if I go 2500/3000 RPM range, I get about 11 knots. But then RPM starts going up and down past 2000 RPM. Engine noise sounds normal, but I can tell not enough power is output on port at that point, as I compensate with rudder towards starboard to keep straight. Also I filled both tanks 3/4 full last week. After several hours over the weekend, port was down by 1/4 tank, where as starboard was down 1/2 tank (these are approximate, but close to what I am saying).... so it's just frustrating, but at least we can take it out this year But it sure would have been great if I can on occasion take it up to 20 knots or so that it is suppose to be capable

[Viper]

So you are sure the above tests specifically were done? Ask for an itemized account of everything, every test they've done. I'd be curious to see it, Including the data off the ECU. I assume by now that all systems such as ignition are back to spec, module in distributor replaced? Tried swapping ECM from one engine to the other and compare?

[km1125]

It's a good idea periodically to summarize the current symptoms and what all has been tested and the KNOWN test results. It also gets confusing switching between threads with similar problems, so doing that periodic summary helps all those that are following along or are trying to help with the solution.

I would definitely find the fix. Running it too long with something wrong could cause other damage to the engine. If lean or timing issues you could burn valves or pistons, if rich you could dilute oil and cause bearing and ring/cylinder issues.

[cpoint]

Source of the post It's a good idea periodically to summarize the current symptoms and what all has been tested and the KNOWN test results. It also gets confusing switching between threads with similar problems, so doing that periodic summary helps all those that are following along or are trying to help with the solution.

I would definitely find the fix. Running it too long with something wrong could cause other damage to the engine. If lean or timing issues you could burn valves or pistons, if rich you could dilute oil and cause bearing and ring/cylinder issues.

km, I will try to summarize after going through all my records.

[390Express]

I noticed that you have similar fuel issues as I am experiencing. I drained my gas as much as possible when I was dry docked, and refilled with 30 gallons to safely get passed the pickup, and make it to the dock and around a bit. My boat was about 10 miles from the marina on land. The combination of the drive to the marina shaking everything up, coupled with the change in angle of the boat (from blocks to being wet), churned up all sorts of gunk in the tank, and changed how much I could have drained if the boat was properly leveled as it sits in the water. I had the same sand-like substance in my gas as well, but mine was more like jello beads. I could break them up with my fingers, but they wouldn't pass through the filter.

I plan on running all of my gas through a cycle, out of the tank from the supply line from the motor, through a remote filter, bypass the engine entirely, through an external fuel pump, back into the tank with some good pressure to churn all of this stuff up again. The pump I have is for a 110 gallon, truck bed mounted fuel tank, to put gas into larger equipment. It is rated for gas, and flows around 30 g/m. I want to run that cycle for 10-15 minutes to keep filtering that gas through a larger, canister style filter (I have the UFO Oberg, which seem to do a great job, but if a small portion of the filter gets clogged, the whole boat won't run. Only about 1" of the 4" filter is worth a damn. The filter is approximately 4", if the 1" piece near the supply line gets clogged, I get no gas to the TBI.) churn everything up, then drain a bit out into a clear jug to see what it looks like. I'll drain it dry again if I have to, there isn't much in it now. There was around 90 gallons when I started, there's less than 25 in it now. I have lawnmower gas for months.

I have read a majority of the thread, but not the whole thing. Forgive me if it has been covered. However, did you look into replacing, swapping, or removing your fuel lines? When my gas separated, the ethanol had an adverse reaction to the rubber gas lines, and the 1/2" I.D. on my main fuel supply line, was reduced down to the point so small I could barely blow through it. You could have good fuel pressure, but bad fuel volume, which isn't noticeable until you load it up. I paid $60 for a new fuel line with new crimped factory style ends on it. It was worth every penny.

Your issue definitely sounds like its fuel delivery related. It could have been ignition, but that stuff is relatively straight forward, you replaced a good majority of it, and I would trust any decent mechanic to diagnose an ignition issue. It's possible for fuel delivery to throw no codes to the ECU, as, in the ECU's mind, everything is running properly for the amount of fuel it is receiving. Keep up the good fight, you'll get through it. I'm in the same boat (same shit, different slip - if you will) if it makes you feel any better.