Vented Cowlings

Jimbirk4

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Joined
May 19, 2005
Messages
26
Does Evinrude make a vented cowling? I have a 40hp. EFI 2001 that doesn't like warm weather. It won't start after running 20 mins. when the outside temps get above 75. However when I remove the cowling after running and leave it off for 10 mins. It will start. It will not unless I remove the cowling or hit the neutral start thing. This only happens in the summertime and not the winter. I did notice that if slide the rubber gromet back that covers the cables entry to the lower engine and get some air to the engine it will start without needing to removing the cowling. My question is, does Evinrude made a cowling that vents, other than through the hand hole. I'm tired of removing the cowling in the summer time. It is a real pain. I have no probs in the wintertime though.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Vented Cowlings

It almost sounds like a vapor lock issue. What octane fuel are you using? If you're using ethanol are you using a stabilizer like Sta Bil or Startron?
 

crxess

Chief Petty Officer
Joined
Apr 30, 2009
Messages
559
Re: Vented Cowlings

Consider replacing your thermostat and completely checking your fuel system.

EFI=electronic fuel injection=closed pressurized system. Should not be vapor locking.

Opening/venting the cowl is masking a problem.
 

Jimbirk4

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Joined
May 19, 2005
Messages
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Re: Vented Cowlings

Consider replacing your thermostat and completely checking your fuel system.

EFI=electronic fuel injection=closed pressurized system. Should not be vapor locking.

Opening/venting the cowl is masking a problem.

I just had the water pump and thermostat replaced 2 mos. ago. Also a compression test, etc. The dealer has no clue.
 

Jimbirk4

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Messages
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Re: Vented Cowlings

It almost sounds like a vapor lock issue. What octane fuel are you using? If you're using ethanol are you using a stabilizer like Sta Bil or Startron?

89 octane. However why does this only happen in the sumertime. Not in the winter when the temps, both air and water are cooler?
 

Jimbirk4

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Re: Vented Cowlings

It almost sounds like a vapor lock issue. What octane fuel are you using? If you're using ethanol are you using a stabilizer like Sta Bil or Startron?

Well I live in Calif. and I think they have to add 10% ethanol to fuel. However why does this only happen in the summer and not the winter months?
 

Jimbirk4

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Joined
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Messages
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Re: Vented Cowlings

Does Evinrude make a vented cowling? I have a 40hp. EFI 2001 that doesn't like warm weather. It won't start after running 20 mins. when the outside temps get above 75. However when I remove the cowling after running and leave it off for 10 mins. It will start. It will not unless I remove the cowling or hit the neutral start thing. This only happens in the summertime and not the winter. I did notice that if slide the rubber gromet back that covers the cables entry to the lower engine and get some air to the engine it will start without needing to removing the cowling. My question is, does Evinrude made a cowling that vents, other than through the hand hole. I'm tired of removing the cowling in the summer time. It is a real pain. I have no probs in the wintertime though.

I think that I have stumped the masters. Even Evinrude mechanics have no clue.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Vented Cowlings

I would check the OE manual but I think the 4 stroke 40 is supposed to use 87 octane. Regardless I'd use whatever octane they recommend, nothing higher. Then treat the fuel with an additive with the enzime for methonal. Make sure you have the right spark plugs. The fuel may be real close to the boiling point and anything can push it over the edge and cause vapor lock.
 

Jimbirk4

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Messages
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Re: Vented Cowlings

Ok so it is a vapor lock issue then. Well I have used 87 octane the last 3 fuel ups. When the engine gets some air it loves it. When the sun beats down on it with the cowling on. It still won't start. Get some air flow of some sort and it will start. I am clueless
 

166oldboat

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Apr 26, 2009
Messages
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Re: Vented Cowlings

i have seen new mercury efi's do this in the summer...a classic case of vapor locking..not sure of a cure though
 

crxess

Chief Petty Officer
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Messages
559
Re: Vented Cowlings

It almost has to be a loss of fuel pressure. Sommething is expanding due to increased heat. Could be a check valve, weak pump, injector leak....etc. pressurized liquid fuel would not boil(vapor lock) pressure loss would allow Gas expansion.
I remove the cowling or hit the neutral start thing.
Do you mean the primer? If so, you are forcing raw fuel allowing it to fire and purge to fuel system.

Think and work logically through the system and the answer will become evident.
Sorry I cannot point to part (X), but not having access to the actual motor with the problem I cannot see all the variables.

Your mechanic is stumped because it is not a common problem with a known solution. He is looking blindly for an answer, much like us. Nudge him in the right direction and his instincts and training should take over. This assuming his desire and capability.
 

Jimbirk4

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Joined
May 19, 2005
Messages
26
Re: Vented Cowlings

It almost has to be a loss of fuel pressure. Sommething is expanding due to increased heat. Could be a check valve, weak pump, injector leak....etc. pressurized liquid fuel would not boil(vapor lock) pressure loss would allow Gas expansion.
Do you mean the primer? If so, you are forcing raw fuel allowing it to fire and purge to fuel system.

Think and work logically through the system and the answer will become evident.
Sorry I cannot point to part (X), but not having access to the actual motor with the problem I cannot see all the variables.

Your mechanic is stumped because it is not a common problem with a known solution. He is looking blindly for an answer, much like us. Nudge him in the right direction and his instincts and training should take over. This assuming his desire and capability.

I have nudged him several times. After a 400 dollar CD pack with no results. That was cheap he told me. I told him . It didn't work. Anyway, I am very frustrated that even the the mechanic at the dealer has no clue. I think I officially have a lemon..
 

Jimbirk4

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Joined
May 19, 2005
Messages
26
Re: Vented Cowlings

It almost has to be a loss of fuel pressure. Sommething is expanding due to increased heat. Could be a check valve, weak pump, injector leak....etc. pressurized liquid fuel would not boil(vapor lock) pressure loss would allow Gas expansion.
Do you mean the primer? If so, you are forcing raw fuel allowing it to fire and purge to fuel system.

Think and work logically through the system and the answer will become evident.
Sorry I cannot point to part (X), but not having access to the actual motor with the problem I cannot see all the variables.

Your mechanic is stumped because it is not a common problem with a known solution. He is looking blindly for an answer, much like us. Nudge him in the right direction and his instincts and training should take over. This assuming his desire and capability.

Yes I am forcing raw fuel through the system to cause the engine to fire. But only in the summer time!!!!!
 

Jimbirk4

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May 19, 2005
Messages
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Re: Vented Cowlings

So I baffle some and all others are looking for answers.. Much appreciated guys.. that is why I'm here
 

Jimbirk4

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Joined
May 19, 2005
Messages
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Re: Vented Cowlings

i have seen new mercury efi's do this in the summer...a classic case of vapor locking..not sure of a cure though

Thank you . I apprieciated that. Answer. Not sure of the cause though. If anyone in here had an answer to my prob. It would be moot by now. However this has been going on for 5yrs. and a lot of investigative money contributed to the dealer and his so called expertise mechanics.. Parts are covered but not the labor.
 

Jimbirk4

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Joined
May 19, 2005
Messages
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Re: Vented Cowlings

Consider replacing your thermostat and completely checking your fuel system.

EFI=electronic fuel injection=closed pressurized system. Should not be vapor locking.

Opening/venting the cowl is masking a problem.

Well I think I should keep on masking the prob. or get a new engine. The parts are covered after replacement. NOT the Labor. 5 yrs of frustration and 3 yrs. of labor. The warranty expired on the labor. Besides it's just a hole in the water where the money goes.
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: Vented Cowlings

Has anyone scouted this engine for an exhaust leak under the cowl.That's the next item I'd look into.A small one could concievably act like your symptom description when the incoming air is warmer and less dense.
 

crxess

Chief Petty Officer
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Messages
559
Re: Vented Cowlings

Jimbirk4
I am in no way trying to slight your problem. I have been there in the past on auto issues with seemingly ghost issues. Having run my own business I hate seeing people charged for failed attempts to guess at solutions. It's just not good practice.

Looking at parts diagrams of your motor, there are several things that could cause/contribute.

Fuel pump and separator Parts
35) fuel pump- motor driven
36) Fuel Pump diaphram
14)Fuel Pump - electric
15)Fuel Regulator
18)Jet-evaporation hose<<< Good place to check

Injector and throttle body parts
2)Fuel injector<<< if expanding from heat it could leak dropping pressure

A crack in or loose line or part in the fuel loop allowing fuel pressure loss.

Caution / Concern
Cowling acts as a noise damper and fire suppressor. Opening/removing while operating can be very dangerous.
http://www.youtube.com/watch?v=ZVzJBpmAfd4

Hope it turns out to be something cheap and simple to correct.
 

Fl_Richard

Lieutenant
Joined
Jan 21, 2005
Messages
1,428
Re: Vented Cowlings

When you lift the engine cover does it start immediately or does it take a while to cool down before it will start?

If it starts immediately, I'd be looking at exhaust gas leak. If it needs to cool down then I'd be looking at fuel delivery.
 

TLL

Petty Officer 3rd Class
Joined
Mar 4, 2004
Messages
92
Re: Vented Cowlings

To properly troubleshoot this motor, your technician has to use the dianostic software to monitor all the sensors when the motor is in its FAILED state. Take him for a boat ride with the laptop hooked up, let it sit and not start, then look at all the sensors for an abnormality. It might be a good idea to record and print all the engine data when it is running properly, and then compare it to when it won't start. When it won't start you also need to know if it has spark, does the fuel pump run, and what the fuel pressure is.
 
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