MP 340 hp - Apparent Fuel System Issue

[rhoadsdj]

I'm having a mystery issue I can't recreate on my 2008 22Ve - I have no doubt this is going to strand me and my family on the lake soon if I can't figure it out!

So far its happened twice to varying degrees of seriousness. In both scenarios the boat starts and runs fine all day - until we anchor and swim for 45 minute to an hour....

After 45-minutes to an hour of having the engine off - it starts back up just fine, and has no issue in forward-idle to get out of the no-wake zone.

Occurrence #1 - as soon as I give it additional gas (beyond forward-idle) - the engine loses power, RPM's drop and the engine almost quits. I put it back in neutral, try again - and no issues.

Occurrence #2 - same scenario as #1, only this time the engine dies - and won't restart. It's turning over and cranking just fine, but it won't start. I try 6-8 times over a 10 minute period and nothing. I wait 10 more minutes trying nothing (while I phone friends to come take my wife and kids home) - then try 1 more time just in case and it fires right up and gets us home safely.

Where do I start checking this? Boat has 200 hours, I have owned for 1 year as the second owner. Last fall I did impeller change and all fluids. Batteries were new last spring.

I started looking at the fuel / water separator and filter but struggled to get it off. I don't think its ever been changed. Should I also look at the check valve on the fuel tank? Any help would be greatly appreciated. Thanks.

[ChrisSnow]

sounds like vapour lock, basically the fuel is evaporating in the system where it should be liquid, and that means you don't get much fuel through the injectors until the engine cools down.
things that help would be running the blower and opening engine hatches.

i'd certainly want to get that fuel filter replaced, they are a right pain to remove, firstly try a strap style filter wrench, then move up to a big pipe wrench, 1 bolt on the bottom removes the cooling plate.

beyond that you could have fuel pressure issues.

[WHammond]

Before you go accessing the fuel tank, i'd just disconnect the fuel line either between the LP and HP fuel pumps, or the line between the fuel rails and the HP pump to see if you get gas when you turn the ignition on and it tries to prime. You can check your fuel pressure at the fuel rails by hooking up a fuel pressure gage to the schrader valve on the top of the engine where the rail crosses over. I'd suggest a fuel pressure gage that lets you bleed it out, that way you can easily bleed the air out of the lines if you disconnect them and you can bleed gas out and see what it looks like after it's been through both pumps and the filter.

I'm assuming you have the same g-force fuel pump/filter that most people have. I just changed the fuel filter on my MP 340 and can confirm it is a SOB to get off. Below is a link to another thread about it, I would suggest removing the 3 bolts for the engine mount to the engine seen in the middle picture and all the hoses to the HP pump so you can remove both the mount and pump. Then you can put the mount in a vice and use a big oil filter wrench to get the filter canister off. Buy a new filter before you remove the old one, opening it up stretches the o-ring and they give you a new one with the new filter. Put anti-seize on the threads when you put it back together with the new filter.


http://www.tigeowners.com/forum/show...ht=fuel+filter
http://marineenginedepot.com/MP/Mari...rce-Fuel-Pump/

[Thegerman618]

Also, just to double check one other thing. The high pressure fuel pump has 2 wires going to it. The red (power) is held on with nothing more than a friction clip, if can come loose and often fall off completely. Make sure it's on and tight, mine came off in the test drive almost didn't buy the boat because of it till they showed me what happened. Usually caused by the cooling line wrapped around it falling down and disconnecting the pump.

But....it does sound like vapor lock. When you pull the bottom plate off the G-Force make sure that seal is clean and free from crud, DO NOT REMOVE THE SEAL FROM THE PLATE, it's epoxied on. Ask me how I figured that out lol. Once my bottom plate was off I fired the boat up and made sure I good clean water flowing through the lines and then reassembled. Heavy duty strap wrench is the trick. (Not the rubber band type) a real cargo strap style wrench <$50.

Good luck side note, equal pressure on the top of pump as you wrench down on the filter cup. That bracket is pretty whimpy and flexs quite a bit and definitely don't want to break the bracket.

[rhoadsdj]

OK thanks, I will check all that out this weekend. Some other info - our marina only sells ethanol-free gasoline, lake temp was 75 F and air temp was 80F. Is it still possible to have vapor lock in that scenario?

Anybody have pictures of the high pressure pump? Where is it exactly? Thanks.

[Stingreye]

Next time it happens, try pushing in the button on the throttle and advancing the throttle to 10-25% while cranking. After wakeboarding or cuising for a long period of time, if I shut down the engine quickly, it has trouble starting and that so far has worked every time for me. I have no idea why this works but it does so its worth attempting. This condition has scared the crap out of me but it starts up every time if I advance the throttle. My boat also starts right away every other time without advancing the throttle. If it was vapor lock would advancing the throttle help?

You thread says the MP 340 (5.7L), so I assume you know for sure you do not have the 6L marine power. In earlier years, the 6L marine power has a known issue that there is a fix for. Its a thermostat fix but similar symptoms and it only works on the 6L.

Note: this is for a PCM motor. Initially, Boatwakes (the REAL mechanic on here) thought mine might be an IAC valve failing but he said it would get worse and happen all the time. I think he thought it was that because advancing throttle bypassed it but I could be wrong. I guess cleaning your IAC (idle air control valve) might not be a bad idea.

[Stingreye]

^^ Mine has happened in December with 60-70* air and 50* water. Still feels like vapor lock though and it only occurs after engine runs hard (wakeboarding or cruising a long time) and then an immediate shut down. It makes me think that the engine block is hot and heating up the fuel rail and giving vapor lock symptoms. At least that has been the guess on my boat. Before i knew the neutral button, advance the throttle trick, i would open the hatch and in 10 minutes it would start (again making me think it could be related to vapor lock).

EDIT: the throttle trick has worked every time

[JCP]

This early in the year the gas at your marina may still be a winter blend. Winter blend will vaporize at a lower temp, meaning vapor locking can occur at a lower temp.

[boatwakes]

Rhoad, sounds very much like an intermittent fuel pump issue and will continue to happen. When vapor lock occurs, it doesn't allow the boat to start after hanging out. Theres a possibility its a wiring connection to the pump, but not likely since it only happens after running the engine. My suggestion would be to replace both pumps.

[Djimax]

It sounds like everyone here knows what they're talking about WAY more than me, but I might as well put my quick 2 cents in.

I have a 2001 2300v and I had a very similar issue. I tried everything just shy of replacing the fuel pump. It turned out that I needed to replace my impeller. It was causing the boat to overheat and wouldnt start up. I know you said you replaced yours, but maybe it isn't a bad idea to check again?

I had a mechanic tell me this: when your boat won't start its only 1 of 2 things - fuel or spark. If you can check fuel pressure at the time of overheating, and check spark, you can figure out what's wrong. I know that there is some extrapolating to do on my statement, but it seems like a pretty good place to at least start the diagnosis.

Anyway, good luck. I know how incredibly frustrating this can be!!


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[Olddude]

Having issues on 08 24 ve with the 340 marine power. Won't restart for 30 to 45 mins after hot shutdown. Also will stumble and die after idling for less than 10 mins (idling in and out of no wake zone coves etc.) Contacted tige then marine power and received free of charge an adaptor that installs on return fuel line and added 3/4" fuel line back to tank in available 3/4" bung in tank. Fixed the issue! About a 2 hour project in 95 degree heat. Shouldn't take an hour in normal circumstances.

[coojac]

Olddude, you are describing the exact situation I have. We are heading to Lake Powell in less than a week and I am worried about taking this boat with me. What did Tige send you that you replaced? Thanks

[Jason AZ]

Olddude - As a recent sufferer of the same problem, any additional info you can provide would be hugely appreciated. Really starting to sour me on the boat that I can't get this resolved. Thanks!

[chpthril]

Jason AZ,

More details: boat year and engine

Whats been done that hasnt fixed it and whats been proven to not be it through diagnostics?

[dj2]

Sounds like the same symptoms I had in my 08 RZ4 when the HP pump was going out/went out. I didn't figure it out before I got stranded.