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Vapor Lock Symptoms & Fuel Line Re-route


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My Monsoon 340 has begun to exhibit the symptoms of vapor lock. It runs like a dream except fails to fire up during hot starts. The plan of record is as follows:

1. Install Vapor Lock Prevention Kit: http://www.bakesonline.com/detail.aspx?ID=2903

2. Insulate fuel pump, lines, and rails, with reflective heat shield tape: http://www.summitracing.com/parts/hsp-340020/overview/

3. Reroute fuel lines further away from block

The challenge is with step #3, rerouting. The fuel line -> fuel rail connectors are non-standard and like nothing I've ever seen before. I can actually freely rotate the connections as if the pressure is held via nothing more than a rubber o-ring at best. No visible threads, nut, etc. to remove I'm afraid to even touch them based on how brittle they appear to be. I've scanned through all fuel connectors on http://www.mcmaster.com and didn't see anything of the sort.

Has anyone inspected, removed, replaced, or rerouted their fuel lines on a '06 Monsoon 340 or any engine which uses similar connections? I'd prefer to replace, reroute, and tape wrap with new marine standard fuel lines.

PS: Upon removing the intake manifold for the first time on my Monsoon 340, I was appalled to see how the fuel line crossover between rails had been routed. The line itself is about 12 inches long, and 8 of them are resting directly against the block! The line which runs from the fuel pump to the first fuel rail also touches the block in a few places. I can see why these setups have issues with vapor lock.

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I fought this battle for about 3 years on my 06 VLX. Tried all the cheap stuff, insulation,ventilating more, key on off several times to clear. Long story short, the extra Vapor lock kit is what finally fixed mine for good. I ended up buying the Carter low pressure marine fuel pump seperately and just piggy backed it's wiring on top of the original pump. Cost just over $100 if I remember correctly. I researched and found the same pump used in the kit sold by SkiDim.

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My Monsoon 340 has begun to exhibit the symptoms of vapor lock. It runs like a dream except fails to fire up during hot starts. The plan of record is as follows:

1. Install Vapor Lock Prevention Kit: http://www.bakesonline.com/detail.aspx?ID=2903

2. Insulate fuel pump, lines, and rails, with reflective heat shield tape: http://www.summitracing.com/parts/hsp-340020/overview/

3. Reroute fuel lines further away from block

The challenge is with step #3, rerouting. The fuel line -> fuel rail connectors are non-standard and like nothing I've ever seen before. I can actually freely rotate the connections as if the pressure is held via nothing more than a rubber o-ring at best. No visible threads, nut, etc. to remove I'm afraid to even touch them based on how brittle they appear to be. I've scanned through all fuel connectors on http://www.mcmaster.com and didn't see anything of the sort.

Has anyone inspected, removed, replaced, or rerouted their fuel lines on a '06 Monsoon 340 or any engine which uses similar connections? I'd prefer to replace, reroute, and tape wrap with new marine standard fuel lines.

PS: Upon removing the intake manifold for the first time on my Monsoon 340, I was appalled to see how the fuel line crossover between rails had been routed. The line itself is about 12 inches long, and 8 of them are resting directly against the block! The line which runs from the fuel pump to the first fuel rail also touches the block in a few places. I can see why these setups have issues with vapor lock.

Vapor lock used to be a problem on many cars and trucks as well until fuel injection came along (early to mid 80's). The use of an in tank fuel pump and increased fuel pressure has all but eliminated this issue on road vehicles. Only the newest boats (from Malibu at least) are equipped with in tank fuel pumps. In boats like ours (earlier with pumps outside the tank) this still leaves an area where vapor lock can occur......in the line between the fuel tank and the fuel pump. That's what this kit from Bakes is designed to address. I don't believe the fuel rail is especially susceptible to vapor lock as the fuel pressure is maintained at least ~32 psi.

Edited by nuttyskier2002
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I've decided to install the pump and wrap some heat reflecting tape first. Will observe results and let you know. Rerouting the lines can come later if there's still an issue.

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I've decided to install the pump and wrap some heat reflecting tape first. Will observe results and let you know. Rerouting the lines can come later if there's still an issue.

I mounted my pump on the Starboard base support for the rear center seat base. Just about 8-10" in front of main pump. Just low enough to not interfere with the storage tray under seat.

Pump will solve your problems.

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I'm experiecing the same symptoms of vapor lock on my 2002 VLX. I just ordered the kit and hopefully it fixes it. The shop I take my boat to normally said from what I described it's vapor lock, but it seems like symptoms from what was described above.

Basically from a hot start, I would need to release the throttle pin, turn the key and give it gas for it to start. That would be intermitent, but it gets annoying. It started just fine, but seems like it needs gas to start the motor.

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What other issues do you have? The fuel pump kit adds another fuel pump tp the boat. It doesn't replace the existing one.

Oh not fuel related, no she runs excellent. My oil pressure gauge is giving me problems

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Well, I'll let you guys know next week when I get the kit installed and bring it out on the lake how it starts. I'm crossing my finger's it solves the issue. Good Luck with the oil pressure gauge. I do notice my oil pressure gauge needle moves pretty good up and down. I don't know if its from the water driving it or something else tho.

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I just completed air filter cleaning, plugs, wires, fuel filter, rotor, distributor cap, heat reflecting tape on rails & crossover line, and vapor lock prevention kit. After running some tests it appears to be better, but not perfect. After getting it fully up to temp, I was able to re-start it about 15 times successfully then I quit. The catch is that on most attempts I had to crank it twice before it would fire. I'd like to get to a position where I feel like it has no choice but to fire up on first attempt every single time.

I read another thread that said the 2awg on the 2006s running from the batteries to engine compartment should have been a 0awg (larger) like other years in order to provide enough current to the fuel pump, starter, plugs, etc. simultaneously. I have a spare battery in my garage so I'm going to wire it directly to the starter and see if it has any effect. I also noticed the ring terminal on the end of the wire is rusty, I'll clean that up too.

I haven't taken voltage measurements at the pump/s, pulled a wire to test spark strength, or tested fuel pressure at the schrader valve yet.

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Ok I think I figured it out... I realized I had the parts laying around to setup a 3rd battery directly in the engine bay, so I got out there and did it. Now, it feels like it has NO CHOICE but to fire right up! It went 5/5 on hot starts then I quit, not a hint of struggle. I'm on a family boating trip next week and had a lot of pressure to get this fixed. I think we have a winner, just going to leave the battery in there, it's an SLA and fits pretty snug in the corner so should be Ok short term.

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Well, I'll let you guys know next week when I get the kit installed and bring it out on the lake how it starts. I'm crossing my finger's it solves the issue. Good Luck with the oil pressure gauge. I do notice my oil pressure gauge needle moves pretty good up and down. I don't know if its from the water driving it or something else tho.

If your gauge is bouncing up & down your sender unit needs replacing, 20 bucks & 5 minutes. Mine always goes between 40psi & 70psi between idle & under load. Last week it suddenly starting running 10psi to 40psi. Boat ran fine, oil level was good, no power loss, no oil in my bilge. Everything is probably okay, but it is driving me nuts why it has a sudden change.

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