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3littlebirds

Won't start after running for awhile and engine warming up

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Please help!  I am trying to trouble shoot a big recurring problem.  I have a 2005 Chap Sunesta, with a Merc 350 Mag fuel injected.  The boat has always run perfect with no issues.  At the start of this year we started experiencing multiple episodes of the boat not wanting to start after running for a little while and the motor warming up.  There has never been any issue with the initial start off the lift (when the boat is cool).  The boat runs great once you are out driving around, pulls great, no spit or sputter, but once you stop somewhere turn off the engine and sit for a bit it doesn't want to start.  If it does it runs for a minute and then sounds like it is starving for fuel.  Once I let it sit for awhile (about an hour), it will eventually start.  I fear one day it won't.  I initially thought it was vapor lock because it seemed to be related to the boat warming up.  I may be wrong but I really think that its a stretch because it's just not getting that hot and I have never had a vapor lock issue in 4 years.  I did go ahead and insulate the gas line and put an ethanol fuel treatment in the tank.    Any thoughts.  I feel like eventually I will be stranded.  could this be vapor lock?  does this sound like a fuel pump?  Once it starts up it runs like a dream.  Or is this something above me, distributor issue, electronic relay.  Please help.  I am lost!  Thanks everyone!!

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2 minutes ago, 3littlebirds said:

Please help!  I am trying to trouble shoot a big recurring problem.  I have a 2005 Chap Sunesta, with a Merc 350 Mag fuel injected.  The boat has always run perfect with no issues.  At the start of this year we started experiencing multiple episodes of the boat not wanting to start after running for a little while and the motor warming up.  There has never been any issue with the initial start off the lift (when the boat is cool).  The boat runs great once you are out driving around, pulls great, no spit or sputter, but once you stop somewhere turn off the engine and sit for a bit it doesn't want to start.  If it does it runs for a minute and then sounds like it is starving for fuel.  Once I let it sit for awhile (about an hour), it will eventually start.  I fear one day it won't.  I initially thought it was vapor lock because it seemed to be related to the boat warming up.  I may be wrong but I really think that its a stretch because it's just not getting that hot and I have never had a vapor lock issue in 4 years.  I did go ahead and insulate the gas line and put an ethanol fuel treatment in the tank.    Any thoughts.  I feel like eventually I will be stranded.  could this be vapor lock?  does this sound like a fuel pump?  Once it starts up it runs like a dream.  Or is this something above me, distributor issue, electronic relay.  Please help.  I am lost!  Thanks everyone!!

You have a two stage fuel system with a low pressure booster pump and a high pressure pump that delivers HP fuel to the fuel rail. Even warm gasoline is harder to pump than cold gasoline so you very well may have a vapor lock issue. On cars, there is a fuel return line that keeps cooler "tank fuel" in circulation back to the tank anytime the engine is running. In order for that to work, the fuel tank operates at a slight positive pressure. USCG does not like that idea on a boat so we are relegated to using water cooled, dead headed fuel pumps which "dump back to the suction style" pressure regulators which add to the hot fuel issue. A weak pump will cause you to have starting problems when the fuel warms a bit as gasoline has a fairly high vapor pressure. Winter blend high C4 content gasoline's are much worse as a few here have found as they fill their boats in early April and are just now getting into summer gas. Your first step is checking your fuel pressure at the rail. A test gauge with hose and fitting are cheap at any auto parts store. Fuel additives will be of little help here. 

Also engine sensors can be affected by heat, but they usually die and stay dead or at least set an alarm so I would stick with fuel.      W

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30 minutes ago, Wingnut said:

You have a two stage fuel system with a low pressure booster pump and a high pressure pump that delivers HP fuel to the fuel rail. Even warm gasoline is harder to pump than cold gasoline so you very well may have a vapor lock issue. On cars, there is a fuel return line that keeps cooler "tank fuel" in circulation back to the tank anytime the engine is running. In order for that to work, the fuel tank operates at a slight positive pressure. USCG does not like that idea on a boat so we are relegated to using water cooled, dead headed fuel pumps which "dump back to the suction style" pressure regulators which add to the hot fuel issue. A weak pump will cause you to have starting problems when the fuel warms a bit as gasoline has a fairly high vapor pressure. Winter blend high C4 content gasoline's are much worse as a few here have found as they fill their boats in early April and are just now getting into summer gas. Your first step is checking your fuel pressure at the rail. A test gauge with hose and fitting are cheap at any auto parts store. Fuel additives will be of little help here. 

Also engine sensors can be affected by heat, but they usually die and stay dead or at least set an alarm so I would stick with fuel.      W

Wingnut, thank you for the quick reply!  The fuel I have in the boat is fuel I put in last October when I winterized the boat and took it off the water.  I typically feel the boat all the way full for the winter months.  There is only a 1/4 tank left but most all of my problems have occurred on this tank of fuel.  The fuel is a pump 87 octane gas with 10% ethanol.  If we think it is vapor lock issues, should I just fill it all the way up with ethanol free fuel?  Does that typically correct this issue, or do I need to get a different type fuel pump? 

I have never had a fuel pump go out on a boat.  I have had a couple on trucks and my experience is with those fuel pumps when they go out, they just quit and the truck wont start.  Are boats the same or could this be an indication that the pump is on its way to stopping?  thanks again truly appreciate the help

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Probably fuel related.  Ethanol, which is an alcohol, absorbs moisture (it's hygroscopic).  In addition, it boils off at a lower temperature than a lot of the other constituents in gasoline (think vapor lock).  Condensation occurs with changes in temperature, and all tanks generally have some "trapped" air that is normal.  First, I'd (safely) open the fuel tank and see if there's any water and rough quantity.  Gasoline floats on water, so I'd pull the sample (stick and a cup) from as close to the bottom as a can with a steady hand.  If there isn't significant water, I'd do the opposite and run it till out/near out after adding a can/half-can of Sea Foam or a bottle or two of Heat.  Then, with the tank empty/near empty, if your motor is so equipped, change the fuel/water separator.  Finally, fill up with fresh marine fuel (non-oxygenated; i.e. no alcohol).  Two things to consider in your winterizing procedure - top off with non-oxygenated fuel, and add an appropriate amount of Sea Foam (one can treats forty gallons) or Heat.  An ounce of prevention... 

P.S.  If there's visible water, pump everything currently in the fuel tank out, then complete the other steps above.  An appropriate amount of Sea Foam or Heat wouldn't hurt the new fuel, and will help emulsify and remove any remaining moisture.

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1 hour ago, 3littlebirds said:

Wingnut, thank you for the quick reply!  The fuel I have in the boat is fuel I put in last October when I winterized the boat and took it off the water.  I typically feel the boat all the way full for the winter months.  There is only a 1/4 tank left but most all of my problems have occurred on this tank of fuel.  The fuel is a pump 87 octane gas with 10% ethanol.  If we think it is vapor lock issues, should I just fill it all the way up with ethanol free fuel?  Does that typically correct this issue, or do I need to get a different type fuel pump? 

I have never had a fuel pump go out on a boat.  I have had a couple on trucks and my experience is with those fuel pumps when they go out, they just quit and the truck wont start.  Are boats the same or could this be an indication that the pump is on its way to stopping?  thanks again truly appreciate the help

Boat fuel pumps are a whole different animal. If it were me I'd run the existing fuel down a much as possible and refill with summer blend. All we have up here is E-10 and have never found that to be an issue, but the only way we can rule out a fuel pump failure is with a pressure test. For what a fuel pump costs (expensive) I'd run out what you have and refill. Letting the blower run for a couple minutes both prior to and after shut-down, and letting the boat idle for a couple minutes before shut-down helps too.  W

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2 hours ago, Curt said:

Probably fuel related.  Ethanol, which is an alcohol, absorbs moisture (it's hygroscopic).  In addition, it boils off at a lower temperature than a lot of the other constituents in gasoline (think vapor lock).  Condensation occurs with changes in temperature, and all tanks generally have some "trapped" air that is normal.  First, I'd (safely) open the fuel tank and see if there's any water and rough quantity.  Gasoline floats on water, so I'd pull the sample (stick and a cup) from as close to the bottom as a can with a steady hand.  If there isn't significant water, I'd do the opposite and run it till out/near out after adding a can/half-can of Sea Foam or a bottle or two of Heat.  Then, with the tank empty/near empty, if your motor is so equipped, change the fuel/water separator.  Finally, fill up with fresh marine fuel (non-oxygenated; i.e. no alcohol).  Two things to consider in your winterizing procedure - top off with non-oxygenated fuel, and add an appropriate amount of Sea Foam (one can treats forty gallons) or Heat.  An ounce of prevention... 

P.S.  If there's visible water, pump everything currently in the fuel tank out, then complete the other steps above.  An appropriate amount of Sea Foam or Heat wouldn't hurt the new fuel, and will help emulsify and remove any remaining moisture.

I don't believe I can get into the tank from the outside.  I will check and see if I have a fuel/water separator, I'm not sure or where that would be located.  I have had several people tell me to add sea foam to the next tank of fuel.  Thank you for the help and advice.  I do appreciate it.

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1 hour ago, Wingnut said:

Boat fuel pumps are a whole different animal. If it were me I'd run the existing fuel down a much as possible and refill with summer blend. All we have up here is E-10 and have never found that to be an issue, but the only way we can rule out a fuel pump failure is with a pressure test. For what a fuel pump costs (expensive) I'd run out what you have and refill. Letting the blower run for a couple minutes both prior to and after shut-down, and letting the boat idle for a couple minutes before shut-down helps too.  W

I definitely have been doing the blowers more and letting it idle, but still its hit or miss on if it starts. 

I read about adding an auxiliary anti vapor lock, low pressure fuel pump?  They look to be 300-400 bucks but I read my motor has an anti vapor lock cool fuel system pump.  I am attaching a picture of what my current pump looks like.  Its at the very bottom of the motor on the port side.

I will see about starting with a pressure test prior to replacing the pump or adding a new one.  Just so I'm clear could you give me a little bit of direction on how to test the fuel pump pressure and what it should run?  I was trying to find directions on how to do a pressure test but have been unsuccessful. 

Thanks again!  very grateful for the advice.  

image.png

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Tank access is possible.  If you are not handy (I'm neither supposing or poking you in the eye - just being safety conscious) don't attempt as gasoline vapors are very flammable and ignite easily if certain safety protocols are not followed. 

Another option, before you get into the tank and/or fuel pump, add a can of Sea Foam (about $10), run the tank out and then fill it with fresh fuel (or bring it up to about half).  Do change the fuel/water separator though if your engine is so equipped (about $15 and less than 30 minutes). 

Given the symptoms you've described, there's a higher probability this is fuel related and you'll soon be enjoying the boat again. 

If fuel is ruled out, i.e. the boat still runs awful, then move to the fuel pump and properly install a "t" and pressure gauge so actual pressure values can be compared to typical operating parameters at idle, and a range of RPMs in neutral and under load (in gear).  Purchase a fitting and gauge for flammable liquid fuel service.  NAPA and Autozone have what you need provided you know the fuel line size.  Likewise, Summit Racing and several other on-line shops will also.  Don't use anything from a home improvement warehouse or the hardware store (i.e. for water or steam).       

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4 hours ago, 3littlebirds said:

I definitely have been doing the blowers more and letting it idle, but still its hit or miss on if it starts. 

I read about adding an auxiliary anti vapor lock, low pressure fuel pump?  They look to be 300-400 bucks but I read my motor has an anti vapor lock cool fuel system pump.  I am attaching a picture of what my current pump looks like.  Its at the very bottom of the motor on the port side.

I will see about starting with a pressure test prior to replacing the pump or adding a new one.  Just so I'm clear could you give me a little bit of direction on how to test the fuel pump pressure and what it should run?  I was trying to find directions on how to do a pressure test but have been unsuccessful. 

Thanks again!  very grateful for the advice.  

image.png

Send me a pm with a valid e-mail address noting you engine particulars and I'll send you a PDF file with instructions.  W

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Slow brain.  Leaking injectors can cause a similar condition. Quick restarts are easy because the leakage rates are slow & need time to bleed the fuel into the cylinders. 30 seconds restarts are normal. Eat lunch. No start.

The fact that running the blower & a idle cool down has helped is a great sign. Have you tried MARINE high test  0 % Ethanol ?  Since I run that in the boats. No problems spring or summer. Probably a emptying of the tank will do the job now.

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13 minutes ago, cyclops2 said:

Slow brain.  Leaking injectors can cause a similar condition. Quick restarts are easy because the leakage rates are slow & need time to bleed the fuel into the cylinders. 30 seconds restarts are normal. Eat lunch. No start.

The fact that running the blower & a idle cool down has helped is a great sign. Have you tried MARINE high test  0 % Ethanol ?  Since I run that in the boats. No problems spring or summer. Probably a emptying of the tank will do the job now.

Thanks for the feed back.  I’m going to try and empty the tank and put non ethanol fuel in and see if that does the trick.  Thanks again

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11 hours ago, 3littlebirds said:

Thanks for the feed back.  I’m going to try and empty the tank and put non ethanol fuel in and see if that does the trick.  Thanks again

About 90% of the boaters in the US are stuck with using E-10, and it works fine.If you can find ethanol free then use it but don't go broke trying to get it.  Bad fuel or winter blend is the issue here I suspect. I suck my tank dry every October and never re-fill until after May 1st. RVP (Reed Vapor Pressure) season is different throughout the country and in Florida they never switch to the higher vapor pressure blend as the government grants them a wavier due to their higher average ambient temperature. Good luck.

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W - Do you know if this engine have a fuel/water separator or "regular" fuel filter?  If there's a fuel/water separator, it should be changed after the tank is empty/near empty and B4 refueling.  My last Mercury, a 5.0 L TKS, didn't and had a traditional in-line fuel filter.  Whatever filters this particular boat has, I believe they should be changed.

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3 hours ago, Curt said:

W - Do you know if this engine have a fuel/water separator or "regular" fuel filter?  If there's a fuel/water separator, it should be changed after the tank is empty/near empty and B4 refueling.  My last Mercury, a 5.0 L TKS, didn't and had a traditional in-line fuel filter.  Whatever filters this particular boat has, I believe they should be changed.

Likely this one.

 

http://www.marinepartsplus.com/catalog/mercruiser/serial/350_MAG_MPI_HORIZON_ALPHA-BRAVO/884717003/12840-75

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22 minutes ago, Wingnut said:

Thanks for all the advice!  You guys have been way more help than any of the dealers in my area!  I do have the fuel water separator you pictured above.  I will pick one up and also change that out when I pump the tank out.  I will certainly keep you posted on things.  Thanks again

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I have a signature 290. V6 vortex MPI. Bad $^& vapor lock in hot weather. Good gas. Idle 5/6 min before shut down no good. Vapor locks. So I installed a electric fuel pump 4 to 7 lbs pressure in the line coming out of the tank to the engine. Sorta like a boost pump. Wired to the key switch. I let this pump run about 20 seconds before trying to start the engine. Knock on wood no vapor lock so far. Bought another electric pump set up for the port engine tonight. Will install next week. Will it solve my vapor lock problem? So far so good but I got to keep trying something cause nothing else helps except opening the engines hatch an waiting an hour or better. 

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Having same problem as OP with my Volvo Penta 8.1 (2007 SSi 256 with 350 hours).  Engine starts great when it's cold (even after sitting for weeks) and when I run it, turn it off, it will immediately start right up again. But if I run it for say 20 or 30 minutes, then anchor up and sit for 30 minutes or an hour and then try to start it all I get is crank crank crank. I'm worried about draining batteries but eventually it will sputter starting.  Otherwise runs smooth as a baby including at WOT.  New fuel a month ago.  Could use fuel filter change (think it's been a year or so).   Very frustrating problem. Also embarrassing with company on board  

W - any final thoughts here?  Haven't seen ya this summer!!!

Any recommendations on a truly qualified Volvo Penta mechanic located on the northern Chesapeake Bay or its tributary rivers (Elk, Sassafrass, Bohemia, North East) for this and all other things VP !  I have lost all faith at the shop at my home marina and their semi-yearly revolving mechanic and techs. 

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I had the same problem and had a fuel booster pump added and it fixed the problem, runs great no problems when hot anymore, this is a common problem, just add the fuel booster pump and it will fix the problem.

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