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dalt1

Do EFI engines vapor lock?

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dalt1

06 VLX Monsoon. Ran for about 4 hours today and all was well. Started and stoped several times in that 4 hours. After the last long run, we shut down for about 30 minutes. When restarting, ran rough and barely idled. Shut it off and tried again but even worse. Finaly would not fire at all, would crank fine but no fire at all. Didn't even try to start. After 15 minutes of towing, tried starting again and it fired but ran very rough. Put it on trailer and took it home. After I got home, about 1 hour, I hooked hose to flush pro and she fired right up and purred like a kitten.

Any Thoughts?

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edwin

I had issues with my 01 SLXi vapor locking when I got it. The problem was finally traced back to fuel. Our region had recently made the switch to reformulated gasoline and it took awhile for them to get things ironed out. After the second season, we never had the issue again. After talking to the Indmar guys at length, we concluded it was similar to when cars back in the early 80's had problems with 'engine run-on'...most of that issue was fuel related as well.

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greenworks

I have trouble with mine if I don't run the blower all the time on warm days. Just a though to try.

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WaveMake'nLSV

Is it possible you took on water in the tank vent? Were you running slammed in the water and surfing, etc...?

Hmmmmmm....never heard of EFI's vapor locking and the tank is vented, so don't see how it would happen, BICBW Dontknow.gif

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greenworks
Is it possible you took on water in the tank vent? Were you running slammed in the water and surfing, etc...?

Hmmmmmm....never heard of EFI's vapor locking and the tank is vented, so don't see how it would happen, BICBW Dontknow.gif

fairly common when running hot the fuel just vaporizes right out of the rail happened to me 2-3 times before I figured out what was going on, however in his case it could have water as well. There was a pretty intense thread last summer on it with several guys reporting the problem

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hawaiianstyln

The blower? These engine are water cooled. Cheers.gif

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skicrave
The blower? These engine are water cooled. Cheers.gif

Yeah, but the fuel rail isn't , so maybe reducing "under-hood" temps a few degrees makes a difference.

This can still be a problem, up until 2007, when they switched to an in tank pump, which should completely eliminate vapor lock.

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greenworks

If your doing decent speed (15mph+) the vents in the front take care of heat but when your surfing or going slower then the blower is a must

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footnlongline
If your doing decent speed (15mph+) the vents in the front take care of heat but when your surfing or going slower then the blower is a must

Plus1.gif What he said! and FWIW make sure your vent hoses are still connected

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dalt1

One other thing that may have contributed, I added the warming tray over the engine this winter. It had wetsuits and neoprene life jackets in it so it probably was like good insulation over the engine. This incident was after a long run at about 25 to 28 MPH for about 35 minutes then shut down and float for about 30 or 40 minutes. Ran Blower for about 4 or 5 minutes before trying to start. It sounds like this is not that unusual, a friend of mine had the same symptoms on his Searay cruiser with twin Merc IO drives yesterday.

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dalt1
If your doing decent speed (15mph+) the vents in the front take care of heat but when your surfing or going slower then the blower is a must

Plus1.gif What he said! and FWIW make sure your vent hoses are still connected

Hoses are good.

Couldn't get back out today but will try again tomorrow.

Edited by dalt1

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dalt1
Is it possible you took on water in the tank vent? Were you running slammed in the water and surfing, etc...?

Hmmmmmm....never heard of EFI's vapor locking and the tank is vented, so don't see how it would happen, BICBW Dontknow.gif

Didn't do any surfing that day shouldn't have got in vent. But did put in half a tank of fuel the night before. Wouldn't think bad fuel, it came from a Shell station on the road, But who knows??

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greenworks
One other thing that may have contributed, I added the warming tray over the engine this winter. It had wetsuits and neoprene life jackets in it so it probably was like good insulation over the engine. This incident was after a long run at about 25 to 28 MPH for about 35 minutes then shut down and float for about 30 or 40 minutes. Ran Blower for about 4 or 5 minutes before trying to start. It sounds like this is not that unusual, a friend of mine had the same symptoms on his Searay cruiser with twin Merc IO drives yesterday.

there is your problem heat build up then shut off and sat for 30 min just leave the blower on during breaks IF you have two batteries just to be safe. If it doesn't start bump the starter which should cause the fuel pump to purge (5 sec) the rails do this a couple times as it will save the cranking trying to get it going again.

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GeorgeWBush

I just had a guy on the lake tell me today about how vapor locks are happening a lot lately due to new fuel mixtures and that the way to fix them on the water is to take a towel dunk it in the lake and then lay it over the the fuel pump for 5 minutes. I'm not that engine savvy so I don't if that is possible.... I just smiled and nodded...

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dalt1

Got back out this morning just to check it out. Ran fine. I guess I need to run blower more from now on. I may add some holes to the side panels to help circulate more air if I don't use blower constantly.

Edited by dalt1

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dalt1
The blower? These engine are water cooled. Cheers.gif

Yeah, but the fuel rail isn't , so maybe reducing "under-hood" temps a few degrees makes a difference.

This can still be a problem, up until 2007, when they switched to an in tank pump, which should completely eliminate vapor lock.

Skicrave,

Where is the pump on the 06 model? I PMed you a couple times last week, did you get them?

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Bill_AirJunky

Hey Denny,

I had a 1994 Mastercraft 205 with the TBI EFI 350 Chevy. I know it's not even close to the same EFI on the Malibu, but it might give you some ideas.

Over the course of 2 summers I had an issue where if I cruised around at low speed on a hot day, then shut the motor down & tried to restart it shortly after, it would turn over, but wouldn't start. Let it cool down for 30 minutes with the spark arrestor off & the motor cover up, and it would start right up. I verified time & time again that I had good spark, and while there was fuel in the EFI (the TBI looks like a carb that you can look down the throat), it wasn't a nice fine mist but larger drops. I suspect vapor lock for 2 years but was told by every mechanic online & in person that EFI does not get vapor lock.

After 2 yrs of trying different things, and taking it to 2 dealers who couldn't solve the problem, I bought the "anti-vapor lock kit" for the carb motors in MC from the early 90s & late 80s from SkiDIM for the problem. It was nothing but several feet of fuel line insulation, or what looked to me like black rubber hose. It came with instructions to depressurize the fuel rail, remove the inline filter & put this insulation on the metal fuel line. There was about 12" - 18" of metal fuel line on either side of the filter & up to the EFI. I never had the problem again.

EFI may or may not ever have the problem, but I had every symptom to indicate I had vapor lock. The Throttle Body Injection may or may not be a "real EFI" unit, but Chevy, MC & Indmar all said they did not know of any vapor lock problems with it. And yet SkiDIM had a fix for it....... for $13.

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mailbudad
Hey Denny,

I had a 1994 Mastercraft 205 with the TBI EFI 350 Chevy. I know it's not even close to the same EFI on the Malibu, but it might give you some ideas.

Over the course of 2 summers I had an issue where if I cruised around at low speed on a hot day, then shut the motor down & tried to restart it shortly after, it would turn over, but wouldn't start. Let it cool down for 30 minutes with the spark arrestor off & the motor cover up, and it would start right up. I verified time & time again that I had good spark, and while there was fuel in the EFI (the TBI looks like a carb that you can look down the throat), it wasn't a nice fine mist but larger drops. I suspect vapor lock for 2 years but was told by every mechanic online & in person that EFI does not get vapor lock.

After 2 yrs of trying different things, and taking it to 2 dealers who couldn't solve the problem, I bought the "anti-vapor lock kit" for the carb motors in MC from the early 90s & late 80s from SkiDIM for the problem. It was nothing but several feet of fuel line insulation, or what looked to me like black rubber hose. It came with instructions to depressurize the fuel rail, remove the inline filter & put this insulation on the metal fuel line. There was about 12" - 18" of metal fuel line on either side of the filter & up to the EFI. I never had the problem again.

EFI may or may not ever have the problem, but I had every symptom to indicate I had vapor lock. The Throttle Body Injection may or may not be a "real EFI" unit, but Chevy, MC & Indmar all said they did not know of any vapor lock problems with it. And yet SkiDIM had a fix for it....... for $13.

Have you changed the fuel filters lately. It sound like you are have fuel delivery problems. This could be due to low fuel level, fuel pump or just a plugged fuel filter. If you had vapour lock, I don't think it would start.

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skicrave
Skicrave,

Where is the pump on the 06 model? I PMed you a couple times last week, did you get them?

It's inside the fuel tank. The entire system is different, from the tank, to the pump, to the high pressure hoses that run to the fuel rail. It's not feasible to retrofit.

Got your PM's, I live on the west coast now, and am no longer involved in that aspect of the industry.

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jetskipro550
I just had a guy on the lake tell me today about how vapor locks are happening a lot lately due to new fuel mixtures and that the way to fix them on the water is to take a towel dunk it in the lake and then lay it over the the fuel pump for 5 minutes. I'm not that engine savvy so I don't if that is possible.... I just smiled and nodded...

There was a big article in the local paper about all the problems that the new fuel mixture is creating for boaters. It said that Detroit Lake marinas will be offering fuel (hopefully) all summer that isn't "blended"

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Bill_AirJunky
Have you changed the fuel filters lately. It sound like you are have fuel delivery problems. This could be due to low fuel level, fuel pump or just a plugged fuel filter. If you had vapour lock, I don't think it would start.

In my own case, I installed new fuel filters and measured the fuel system pressure. I'd suggest doing all these things before you assume it's vapor lock.

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VLXRonnie

I was having the same issues last year. No luck with the dealers either. I know some have changed the engine thermostat. Dont really recall the instance. Something about the engine thinking that the engine was cold and flooding the engine with fuel for a cold start. BICBW. I just started using the blower alot more and would prime the fuel lines before I actually cranked the engine. Haven't had any instances since then. Dont know if it helps you ,but that was my experience.

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dalt1
Hey Denny,

I had a 1994 Mastercraft 205 with the TBI EFI 350 Chevy. I know it's not even close to the same EFI on the Malibu, but it might give you some ideas.

Over the course of 2 summers I had an issue where if I cruised around at low speed on a hot day, then shut the motor down & tried to restart it shortly after, it would turn over, but wouldn't start. Let it cool down for 30 minutes with the spark arrestor off & the motor cover up, and it would start right up. I verified time & time again that I had good spark, and while there was fuel in the EFI (the TBI looks like a carb that you can look down the throat), it wasn't a nice fine mist but larger drops. I suspect vapor lock for 2 years but was told by every mechanic online & in person that EFI does not get vapor lock.

After 2 yrs of trying different things, and taking it to 2 dealers who couldn't solve the problem, I bought the "anti-vapor lock kit" for the carb motors in MC from the early 90s & late 80s from SkiDIM for the problem. It was nothing but several feet of fuel line insulation, or what looked to me like black rubber hose. It came with instructions to depressurize the fuel rail, remove the inline filter & put this insulation on the metal fuel line. There was about 12" - 18" of metal fuel line on either side of the filter & up to the EFI. I never had the problem again.

EFI may or may not ever have the problem, but I had every symptom to indicate I had vapor lock. The Throttle Body Injection may or may not be a "real EFI" unit, but Chevy, MC & Indmar all said they did not know of any vapor lock problems with it. And yet SkiDIM had a fix for it....... for $13.

Have you changed the fuel filters lately. It sound like you are have fuel delivery problems. This could be due to low fuel level, fuel pump or just a plugged fuel filter. If you had vapour lock, I don't think it would start.

Filter replaced less than 10 hours prior to problem.

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dalt1

Just got back from TN Hydrofoil Fly In. Ran 3 full tanks out in 3 days, and no problem as before. Did use blower a bit more and weather was not extremely hot. Now to find out why dash screen (2 times) put up a no ECM signal. Time for new thread. Thanks to all for the input.

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NorthernDancer
06 VLX Monsoon. Ran for about 4 hours today and all was well. Started and stoped several times in that 4 hours. After the last long run, we shut down for about 30 minutes. When restarting, ran rough and barely idled. Shut it off and tried again but even worse. Finaly would not fire at all, would crank fine but no fire at all. Didn't even try to start. After 15 minutes of towing, tried starting again and it fired but ran very rough. Put it on trailer and took it home. After I got home, about 1 hour, I hooked hose to flush pro and she fired right up and purred like a kitten.

Any Thoughts?

It sounds exactly like vapour lock. There are a lot of thoughts on fuel type/water etc.but the problem is the on-motor fuel pump and the rails sitting next to all that hot steel. I totally drained my tank last year,changed all the fuel filters and the fuel water separator and still had the same problem with good fresh gas from a different supplier. Finally got the straight goods from our local dealer. The problem is "heat soak'. When you shut down the hot engine and let it sit for a while the radiant heat off the manifolds simply vapourizes the fuel in the rails and your stuck until it totally cools off. The secret is to keep a couple of old towels and when you want to shut down for a short period of time while the engine is hot soak the towels and lay them directly on the rails. Works like a charm, just don't forget to take them off before you go.

This is one reason I switched to the new 340 Cat-EX with the in tank pump, I have heard, however, that you shouldn't run your tank less than 1/3 on a hot day with this pump as the pump can overheat if it is not covered in fuel.

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