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Mino

Boat Smells like it is running rich

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Mino

I have a 2005 Response LXI with the 340 Monsoon. The boat smells like it is running rich. Every now and again it runs a little rough as well. So far I have changed the plugs, new fuel filter and made sure the fuel pump screen is clean. I did pull one on the new plugs after a couple weeks of use and saw that there was soot build up on the plug. Also pulled a couple of other plugs to see that they were clean.

I would take it to a dealership if there were any in the area that I could trust, but the closest Malibu dealership is 2 1/2 hours away. So I am wondering if anyone has any suggestions of what I can check myself to try to identify what is causing the problem.

Thanks in advance for the help.

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Green_Giant

Did you check / change the cap and rotor recently? That will certainly account for a rough idle but not sure about rich. Only other things I've heard is a sticky injector, malfunctioning fuel pressure regulator or a temp snsor thatis telling your ECM that your motor is cold when it really isn't. But I'm no expert.

Good luck!

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JasonK

It doesn't have to be a Malibu dealer, take it to any Indmar cert. shop.

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footnlongline

Hows your temperature, if yout t stat is stuck open, the computer will cause it to run rich

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Bake's Marine

On that motor with out the right tools this would be really hard to diagnose because it could be a number of things.

You need Diacom to talk with the engine ECM to interpret the data going in and coming out. And you also need a fuel pressure gauge to check fuel pressure at key up,idle and at 3,000 RPM.

I would track down a Indmar dealer, but i would make sure you send it to somebody you trust.

-Paul

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Baddog

I would vote strongly for the engine temp sensor. Mine went bad and it smelled like fuel and running rich and would also become hard to restart when warm.

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Mino

I would vote strongly for the engine temp sensor. Mine went bad and it smelled like fuel and running rich and would also become hard to restart when warm.

Baddog,

Where is the engine temp sensor located?

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Baddog

Baddog,

Where is the engine temp sensor located?

On a DD it will be on the top of the engine at the front on the port side. it is a little screw in sensor with a 2-wire (I think) conector. Costs about $35 and takes all of 5 minutes to change.

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electricjohn

You can check it yourself if you have a multi-meter (ohm-meter). At room temperature you should measure 2400 ohms, and at operating temperature you should measure 500 ohms. The leads (tips) of the meter are hard to fit into the connector point on the sensor, but they will fit.

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kylegansel

I'm dealing with the issue where my boat won't start when it's been warmed up and then sits for about 15 minutes.  Sounds like the fuel pump is starving for gas a bit.  I also think I'm running rich because my plugs are a bit wet and dark.  Does the Engine Temp Sensor actual regulate fuel delivery?  I'm thinking of just replacing the Engine Temp Sensor, Thermostat, Fuel Pressure Regulator, and the plugs and seeing if it improves.  

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BlindSquirrel
54 minutes ago, kylegansel said:

I'm dealing with the issue where my boat won't start when it's been warmed up and then sits for about 15 minutes.  Sounds like the fuel pump is starving for gas a bit.  I also think I'm running rich because my plugs are a bit wet and dark.  Does the Engine Temp Sensor actual regulate fuel delivery?  I'm thinking of just replacing the Engine Temp Sensor, Thermostat, Fuel Pressure Regulator, and the plugs and seeing if it improves.  

Do you run ethanol free gas? It sounds like you are describing a vapor lock condition. What year is your tug?

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kylegansel

@BlindSquirrelI just started running ethanol free gas.  I'm about 20 gallons in.  It's all I'm going to run from now on.  2005 Malibu Response LX w/ Indmar 320 LCR.  I've had this boat for 5 years and I've never had an issue with vapor lock.  I burn through 20 gallons a weekend so it doesn't sit much.  I'm curious why now?  

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BlindSquirrel
19 hours ago, kylegansel said:

@BlindSquirrelI just started running ethanol free gas.  I'm about 20 gallons in.  It's all I'm going to run from now on.  2005 Malibu Response LX w/ Indmar 320 LCR.  I've had this boat for 5 years and I've never had an issue with vapor lock.  I burn through 20 gallons a weekend so it doesn't sit much.  I'm curious why now?  

Well, old fuel won’t cause this problem. Vapor lock is when the fuel in the fuel pump turns to vapor instead of liquid, due to the ethanol having much lower heat tolerance. An easy way to tell if vapor lock is your issue, next time it happens put a rag that you dip in the water around the fuel pump to cool it down. If she starts up after that.... there’s your problem. There are several solutions, some add another fuel pump, some prop open the engine bay to keep it cool... I just make sure and use ethanol free fuel at all costs. Gas stations here in Kansas say it could contain up to 10%, meaning it will vary possibly causing your inconsistency. Just search vapor lock on this forum, it’s been discussed at great length with great info.

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kylegansel

Thanks.  After a few more cans I should be ethanol free here all the time!!  It’s just odd that I’ve never had the issue before.  I did test the midgrade I was using and it had 9% ethanol.  Can ethanol fuels cause the engine to run rich also?

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CDOBU

I own a 2001 Sunsetter VLX, same Indmar 340 engine with fuel injection, which is now definitely running rich.  When I rev the engine in neutral, it is pumping black smoke,  and engine hesitates coming out of the hole - almost stalls going to full throttle from idle (i.e. when pulling a skier out).   Just changed rotor, coil, alternator and battery as it kept blowing the ignition control module (have replaced that ICM 5X in the past two seasons!).  I doubt the tow issues are related, but has anyone dealt with either engine running rich or blowing the ICM repeatedly?

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formulaben

Did you use the thermal paste when you installed the ICM?  If not used, it overheats and burns up.

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CDOBU

Yes, used the silicone dielectric grease when installing the ICM all 5X, so thinking that ICM problem  is likely a voltage issue, voltmeter gauge is all over the place, so might be a bad gauge as well, planning to replace that this winter also.  Hence the new coil, new alternator and new battery, also new plugs - but not ruling out the temp issue, particularly if that temp sensor is causing the boat to run rich, maybe the T-stat needs to be replaced as well?  For the cost of a T-stat, temp sensor and maybe even fuel pump regulator, might be worth a shot?  Also, I have been told that having the injector ports tuned can make a huge difference in performance, has anyone had that done?

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justgary
3 hours ago, CDOBU said:

Yes, used the silicone dielectric grease when installing the ICM all 5X, so thinking that ICM problem  is likely a voltage issue, voltmeter gauge is all over the place, so might be a bad gauge as well, planning to replace that this winter also.  Hence the new coil, new alternator and new battery, also new plugs - but not ruling out the temp issue, particularly if that temp sensor is causing the boat to run rich, maybe the T-stat needs to be replaced as well?  For the cost of a T-stat, temp sensor and maybe even fuel pump regulator, might be worth a shot?  Also, I have been told that having the injector ports tuned can make a huge difference in performance, has anyone had that done?

Fix the voltage problem before you try to fix the poor run quality.  Consider removing and cleaning the power and ground connections at the engine, under the dash, and at the battery.  You might also want to check the cannon plug to make sure it is clean and making good contact.  The other issues may go away when you get reliable system voltage.

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Bozboat
Posted (edited)

@justgary ‘s plan makes sense. Think of the engine needing fuel, spark, air and cooling. Try to fix one system at a time. I can tell you that I have thrown parts at it before, it’s entertaining, expensive, and frustrating. The better plan is to try to isolate the problem, one system at a time. 

 

 

Edited by Bozboat

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CDOBU

Update, my boat mechanic let me use their diagnostic tool, which showed no codes.  When we started up the boat, checked fuel pressure at various speeds, all normal - so clearly not a fuel pump issue, but engine still running rich, hesitating when accelerating rapidly. Removed leads to temp sensor with engine running, engine smoothed right out, so have ordered new temp sensor, and throttle position sensor to assure that is not part of the issue.  More to follow after this weekend when those parts are replaced. Looking more like that temp sensor was the culprit, similar to others' experience here on the forum.

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CDOBU

We have checked all engine, battery ground connections, but will double check all again this weekend as well.  Was not aware of that ground connection under dash - where is that located?  That may be why the voltmeter is reading all over the place!

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formulaben

There is a negative buss bar under the helm adjacent the gunnel.  If you get on your back and look up, you'll see a LOT of black wires going to it.  Tighten them ALL, especially the big one that ties it to the electrical system.  Also check the connections at the alternator, starter, engine block negative terminal and battery terminals (and battery switch, if installed.)

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