Engine backfiring

[miller]

Hello. My 2006 24ve (MP 5.7) had problems starting (it would turn over but not fire). I took it to my local Tige dealer where after 2 weeks they replaced the distributor cap, rotor, 8 plugs, and ignition relay. I picked it up yesterday and took it out today (with a full boat of family and friends to go surfing) and when I try to get the boat on plane, I lose power and the engine starts to backfire. After doing a little research, it sounds like the wires have been crossed between the plugs and the distributor cap. So my questions are: (1) does this assessment sound correct, and (2) how do i know the order of the wire from the plugs to the distributor cap?
Thanks in advance.
Ryan

[ericinmich]

Could be the issue, backfiring usually is a spark related issue.

1-8-4-3-6-5-7-2 is the firing order

Did they replace the wires? If not, they should be the correct length (longest to shortest) thus easy to sort out how they fit to give the firing order. If they are also no, they could of screwed up lengths so harder to sort out order. Google is your friend...

Does it idle OK? Odd if you say yes as swapped order would have it running 2 or more cylinders down and you should notice it at idle.

[miller]

At first it seemed to idle ok. However, after I took it out for a second time today, it idled real rough. I'll try to sort it out.

[boatwakes]

My guess would be water in the fuel but when did the problem start?

[miller]

We had a very wet spring/summer here in MN. Due to the high water, we had "no-wake" restrictions over the entire lake (Lake Minnetonka). So the first 5+ times out, we never had it over 5 mph and i never noticed an issue. The wake restrictions were lifted and the first time out "with a wake" on Aug 3rd, it ran fine. We stopped and had dinner at a restaurant on the lake, and it would not start back up. So, I replace the fuel filter and it would not start. I took it to the our tige dealer and picked it up yesterday, which is how i got to the issue today. So, I've put in about 8 gallons of gas into the boat this year along with ethanol treatment in the gas.

[gwhite94]

I would take Boatwakes advice and check\replace the water seperator filter.

[boatwakes]

It's fuel related, maybe even a combination of water absorbed into the fuel and more than likely a failing high pressure fuel pump. If you pull the fuel filter and smell the gas, ethanol gas with absorbed water in it will smell like alcohol and generally evaporate extremely fast, like an exposed quart will evaporate 2/3 of itself in an 8 hour period. Pressure test the fuel system with and without load. The backfiring issue on an efi motor indicates one of two things: a sticky intake valve or a lean fuel condition (barring a timing issue but the motor ran fine before so I'll rule that out for now). Start with the basics of firing order, fuel condition and fuel pressure and report back what you find.

[chpthril]

Since the boat has a different symptom than what the boat went in for, I would absolutely revisit the parts and labor that were done when in for repairs. The root issue may just have progressed, but you could also have a defective new part now.

[miller]

I took it back to the dealer yesterday and they reviewed the wiring and said it was correct. After running it off the hose they found no issue. So, I met the mechanic at the lake to test it under load and it ran fine which seemed odd. The mechanic thought is was moisture in the fuel and on Sunday (when i had the backfiring issues) we had a very humid day where condensation could have caused the problem. The Tige dealer was quick to jump on this issue and made sure everything was resolved, which i greatly appreciated. I took it surfing last night (with the same friends and family from Sunday) and it performed without issue. I'm done using ethanol gas. I will have to drive a little further to by real gas, but it sounds like it is worth it. Thanks for the help with this.

[chpthril]

I'm done using ethanol gas. I will have to drive a little further to by real gas, but it sounds like it is worth it

IMO, you are jumping to a conclusion. I see nothing here to indicate this was an issue caused by the use of Ethanol blended fuel. When I see backfiring, ignition issue is the first thing to cross my mind. Ignition module getting warm and glitching out.

If you have an ethanol issue, pull the water/fuel filter and catch every bit of spillage and then dump it and the filter contents into a glass jar. Your boat's engine and fuel system will handle ethanol just fine, but with boats and other weekend toys, we just need to step up the level of preventative maintenance, as compared to a car thats driven daily and has a closed EVAP system.

[Wakeman22]

I have had similar problems over the years. It has always come back to the fuel I used. After running it out or adding octane boast the problems went away. I just had this similar issue. Changed filter. No water in fuel. Changed plugs, they were 7 years old. Same issue. Added octane boats and the problems were resolved. Ran another tank through of fresh fuel and problems are gone. Just my 2 cents.

[miller]

After running it last Monday (8/25) without any issue, i took it out last Friday and the 'loss of power' issue continued. I did not get the backfiring, but after i put the engine under load, i would lose power (RPMs would drop to about 1000 under load). So, i ended up draining the gas tank (until there was about 3/4" in the bottom), added 15 gallons of non-oxygenated gas, 2 cans of seafoam, and took it back out. The boat initially struggled and then ran perfect for about an hour, however, the symptoms returned but were not as severe. I run the boat up to about 2500 RPMs, it stays running for a 5-10 seconds, and then the RPMs drop down about 500-1000. My current thought is to replace the fuel filter again since it may be clogged with the bad gas and run through the remaining gas. I did pull the filter yesterday, dumping the contents of the fuel filter/separator canister into a glass jar and did not find any water in the jar. However, the gas did not smell like normal gas. I can't seem to find a filter locally, so i had to order one online. Does it make sense that a filter would be clogged after 1 month? Or should i just run through the remaining gas with the current filter?
Ryan

[chpthril]

Cut the old one open and see what's caught in the element.

[miller]

So i replaced my fuel filter and still had the same issues. I then attached my fuel pressure gauge and it started to drop from 50psi at idle as i added throttle. here is the video

. So to me this seems like a high pressure fuel pump issue. Does that seem correct?

[chpthril]

Pull the pickup out of the tank and look for a blockage as well as inspect the hoses all the way from the tank to the fuel rail. it would also be a good idea to put a volt meter on the fuel pump and do that same test.