Ever thought you were about to kiss your boat goodbye?

So last Saturday we went to the Mile High Meet and Greet down at the Pueblo Reservoir which was basically a big party at party cove. When we were getting ready leave a couple people needed a ride back to the marina and I agreed to take them. My 02 Supra SSV now has 11 people in it and I’m a little short on life vests : ( . As we leave the cove the winds pick up creating some rather large swells. When we pulled out of the no wake zone I punch the throttle, but the engine bogs down and won’t go past 2k rpm. Every time the engine try’s to get power it brings the nose up, then bogs bringing nose back down hard. Mix the weight from all the people, large swells, and the bogging down equaled the perfect storm. The front end took on so much water that the bow was completely full and quickly was spreading to the back. The front end immediately submerged and that’s when I thought we were done. I finally got smart and sent everyone to the very rear of the boat, flipped the bilge and drains for all ballast system (bags were not in at the time), and hopped in the bow scooping all the water out with a life jacket. Somehow that worked and the boat was saved.


Now that storytime is over, I need the figure out whats wrong with this motor. I took it out Monday and ran fine for about ten minutes and started to bog down again. It will move until around 2000 rpm and then it will lose power and back fire. I believe it might be a fuel issue. If I turn the key a couple times and let the pump prime the system, the boat will run good for 20 seconds and eventually start running like **** again. I thought it could be vapor lock since it was sitting in a hot cove all day, but on Monday it stopped running good fairly quick. Any thoughts? Maybe the following video could help.

Here's a short vid of the meet and greet

https://fbcdn-video-a.akamaihd.net/h...0c4e63799d487b

A bad fuel pump or clogged fuel filter may do that.

I'd start with the fuel filter. Usually when a fuel pump dies, it's dead. They don't start struggling. A clogged filter can allow enough fuel through to run but then starve the motor as soon as you try to give it more.

I'd start with a fuel pressure test first. Rent/buy a fuel pressure gauge as it will serve you well in the future. Most fuel injected boats should be around 40 psi but you can research your particular engine/fuel pump to see if it's supposed to be different. If it's 40 psi even when she's stumbling then your problem lies somewhere other than the filter/pump/lines. It could still be injectors but I'd eliminate a few simpler things first.

It's unlikely that you're starving for air since boats usually don't have real air filters but you can check your spark arester to make sure there's not a plastic bag sucked onto the front or something. You obviously have spark at least to some extent but it could be a more involved ignition or electronics issue.

So I ran back to the lake today to see if it would run better on Stabilfuel, octane booster, and 91. I put 87 in it previously and was hoping that was the issue. NOT. Since that didn't work I pulled off the spark arrest to watch throttle body injection spray fuel. Once it hits a higher rpm it stops spraying fuel completely in one of the two injectors. The injectors switch back and forth with not spraying. My current thought is to order a fuel filter and do a fuel pressure test before I spend the $350 to replace the fuel pump. I doubt both injectors would go out at the same time so I'm ruling out those as the issue. Thanks everyone for your responses!

Sounds like a ethanol issue. I would buy some HEET at the local auto parts store and run in through. You put it in the tank shake the boat around, then run it for a while to eat up all the garbage.

http://www.thetoolworkshop.com/golde...eeze28201.aspx

Also check the cap and rotor. I had the same issue and it fixed it

Sounds like a fuel pressure issue either due to an obstruction or pump issue but I'm not too familiar with the "firing order" of injectors in a TBI. Is it alternating between the injectors rhythmically or randomly? If it's rhythmically then maybe that's by design. Something along the lines of low duty cycle at idle for both injectors and then alternating high duty cycle at partial throttle then high duty cycle on both injectors at WOT. That's just a theory I made up to explain that behavior if it's rhythmic so you'd probably want to get better info from someone who has dealt with TBI.

You can also pop the injectors off and have them cleaned. Even if it's not the source of your problem it's probably worth doing. I've heard Napa offers this service now but I haven't used them.

You could also send them off to these guys if you have the time:
http://cleaninginjector.com/

Its random. At idle, both injectors are spiting fuel when you rev up they'll cut off back and forth. My guess is there fighting each other for fuel. Hopefully a filter cleans this up. If not then I'll move on to the pump.

I wouldn't put heat in a boat that is having ethanol problems. HEET is mostly alcohol and that's not what you need to burn the bad fuel through. I had a problem with ethanol last year. do a search for phase separation. if this is the problem then all of your octane has been separated out. I pored my water separator into a clear bottle. it looks kind of like water in fuel but backwards. I had a lot of fuel in the boat so removing it all was not a option I wanted. I ran it for about 10 min then emptied the separator. over and over until it looked pretty good. Then I put a new separator on and added a bunch of octane boost and ethanol treatment it worked but I wanted to burn that tank of fuel as fast as I could.

Originally Posted by nailem

I wouldn't put heat in a boat that is having ethanol problems. HEET is mostly alcohol and that's not what you need to burn the bad fuel through. I had a problem with ethanol last year. do a search for phase separation. if this is the problem then all of your octane has been separated out. I pored my water separator into a clear bottle. it looks kind of like water in fuel but backwards. I had a lot of fuel in the boat so removing it all was not a option I wanted. I ran it for about 10 min then emptied the separator. over and over until it looked pretty good. Then I put a new separator on and added a bunch of octane boost and ethanol treatment it worked but I wanted to burn that tank of fuel as fast as I could.

It looked like water in the fuel, because that's what it is. Ethanol breaks the gasoline down, HEET eats all the water. I was stranded in my other boat a triple engine big block boat on Lake Pontchartrain, when ethanol first came out. Replaced every part to the fuel system I could. Only to have it get fixed by running HEET through it.

I am just trying to save some one else the headache I went through.

This might be a long shot, but this happened to our boat years ago. Everything ran fine for the most part, but randomly it would fall on it's face and bog down like it was being starved of fuel. Similar to what you are experiencing. It was a 5.0L 302 with 4 barrel carb. Apparently somewhere along the line doing work on it, a pencil lead had broken off and found it's way in the gas tank. This got sucked up in through the pump, the filter, and the fuel line and ended up in the bowl of the carb. It didn't cause problems until you had been on the throttle for a while and the fuel in the bowl would run low. The suction would occasionally suck the pencil lead into the hole for the jet in just the right way clogging it and bogging the engine down. Sometimes it would get sucked back there perpendicular to the hole or not at all and you wouldn't notice a difference because fuel could still get by, but every now and then the stars would align and you'd get an engine that bogged down on you, then it would clear itself after you got off the throttle and went again, sometimes.

Obviously check your fuel filter, water separator, make sure you have good clean fuel in it, use some heet to dry out any water that may be in the tank from over the winter, possibly drain the entire tank and start with fresh gas. But you may want to look into pulling the carb and rebuilding it and cleaning it out. You may have some debris or dirt that managed to get stuck in there.

phase seperation: http://youtu.be/h35x8drMhBI

I had the same problem in my 02. It ended up being a clogged filter. Changed the pump, ignition system, purged the lines, everything except the simplest thing. Change your filter.

Phase separation is different. Yes it has to do with ethanol's ability to absorb water but it us a separation of the fuel. Normal water in gas when poured into a clear bottle the gas floats on top with water on the bottom. Phase separation is the opposite, the heavy fuel is on the bottom and what's left on top has little or no octane. I guess if it sits long enough it will be 3 parts with the 3rd part being water.

You can use a timing light, hooked up like you would for checking timing, but us it to better visualize the injector spray pattern too. Should be nice cone spray from both if I remember right. Obviously after you change the filter and get the injector drop out issue fixed.

Cheers,
DC

Water in fuel. Change fuel filter.

Won't rev over certain RPM and backfiring (through intake typically) is a lean condition. Check your filters and failing that your tank pickup. Is this carb or EFI? If carb you may have a screen in the ports of the fuel bowls clogged or junk in the bowls. If EFI, good luck.

Also check your timing. Make sure initial is correct (generally around 10*) and that it is advancing fully by 3000 RPM, over 30* total. Could be rusty/stuck advance mechanism. If so clean and lubricate.