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Discussion in 'Boat Tips' started by catwhisper, Oct 15, 2009.
2004 25hp merc runs great at idle and low rpms but half way starts to bog. any help?
My uncles atv does that, now im no mechanic and dont know a darn thing about it but I think something could be blocked in the fuel line or punctured somewhere.
Something that happened to me years ago was that my choke was getting stuck on. The carberatuer may also be getting stuck. It could also be a fuel restriction. Start simple. It probably is something simple. Let me know when you find out. I am curious
I'm not a mechanic but would suggest using some sea foam before taring anything down. Sea foam will clean it up like your dinner plate.
sounds like you have a float stuck in your carb.... learn how to do a complete carb disassemble and cleaning in about 20mins. Its not that hard. Recommeded to put a fuel filter inline between your tank and motor to help stop little pieces of junk from getting in your carb and plugging up a jet or causing the float to stick.
If its fuel injected... then I have no clue.
One story I have is every time you started the engine, the throttle was WIDE OPEN.... drove me nuts for about a day. Finally took the carb off to find a dead baby snake wrapped up inside.
Buddy of mine had same problem earlier this year. His carbs were getting garbage in the jets. He found out the hard way that alchohol in the gas breaks down the rubber hoses on older boats. After rebuilding the carbs and replacing the fuel lines, it worked fine. With a little restriction, the boat would not plane out, and got worse as it got more clogged. Sounds like you have trash of some sort in the carbs (not likely the hoses breaking down in side them in your case since it is an 04 model, but trash in the carbs is a very common problem). It is an easy job to rebuild the carbs, they are very simple to work on. The Seafoam is also a good idea to clean out the fuel system and clean out carbon build up.
Also, check the vent on the gas tank. Last weekend, I topped the fuel tank off before a tournament. When were were catching bait, I could get on a plane, and it would shut down to an idle almost instantly. Looked back and the primer bulb was sucked flat. I had to shut the motor down and work the bulb until it was reinflated. Started back up and it took a few minutes of riding around slowly to burn enough gas to allow the tank to vent properly.
sounds like the high speed jets are plugged! it's a pretty common problem. trash or varnished gas will plug it if left sitting with gas in the motor.
if carburator and it happens when you give it gas it would likely be the accelerator pump. they dry up when it sits over the winter cheep easy fix.
just needs a good cleaning when get it clean put you some stabile in your fuel it will help keep all the varnish down and put a inline filter
I agree I think a carb rebuild is in order. Might get by with a cleaning. But why not throw a kit in it while you have it apart. Should be a cheap and easy fix.
thanks you guys, I'm glad all of you think it is feul related i will tear it down tomorrow and clean it good and check everything yall told me. also i'll add a filter. let ya know.
agreed with the ethnol in the fuel.. won't use it ever again. Totally destroyed my fuel lines and fuel pump on my boat motor, it was a mess to get it all cleaned out and replaced. My motorcycle gets 7 mpg better gas mileage on 100% pure gasoline and my truck gets 3 mpg better. I just don't see the cost savings over time, let alone the hassles it has caused me.
i tore the carb down today and found little black particles all in the carb. also the accelerator pump looked like it was melted. that does it for ethanol added gas. gotta find a station that has 100% petro. will order a kit tommorrow. problably next week before i can go fishing now :angry:
thank all of you for you input. i learned some very useful info. will update when kit comes in. yall catch a fish for me:smile2:
I guess you learned.... I like the "sea foam Idea'.... try it you like it... also.... some additive..... stabil..... and an ole buddy of mine does the alcohol treatment to get the stuff out of the feul tanks.....
tight line... Bayrunner Ray
Those little black particles are probably pieces of fuel line, don't forget to
put new fuel line on it too or you'll be pulling the carb off again.
I agree 100% here, sounds like you need to change all the fuel lines in the system. This is what I was talking about in my original post. The fuel lines break down from the inside and will continue to cause carb cloging problems. The outside of the hoses may look great, but the inside will be falling apart.
Also, Ray mentioned and alcohol treatment. Can you explain what you are talking about. I don't know of any alcohol treatment that will remove the alcohol from the gas, and would love to know if there is something out there that will do that. The staybil and seafoam (fuel conditioner addatives) will help keep the alcohol from attracting and bonding to water and will help with phase seperation as the gas sits, which will help keep the tank cleaner and gas fresher, but it doesn't eliminate the alcohol content in the gas. Good thread guys, hope you get it fixed up in a few days.
I think we all jump on ethanol fuel and blame all our problems on it too easily,yes I'm sure some of the motors we have were never designed for it and that there has been ethanol caused problems,a partially melted accelerator pump is not from fuel but from to hot of a temp,causes could be running with not enough oil to gas ratio,a water pump impellor thsat needs replaced causing slightly higher running temps,and their are a few other causes that could cause motor overheating,any motor built within the last 15 years should run the ethanol blend without problems caused by the gas,the engines before that were not built with ethanol in mind and therefore might need some changes to burn it efficiently. The same can be said of your cars and trucks,they are not set up to run on ethanol blends and will not perform to their potential without being tuned to run on it,ethanol will get better milage than gas if your vehicle is tuned to run it,but as they are all tuned to run on gas at gas burning tempatures they will run better on gas. It's too easy to bame everything on ethanol,when things are old and prone to breakdowns anyway. As far as fuel line rotting because of it,I've never had that problem,but if your using old gas line left in the sun and heat year-around things are going to break down and degrade no matter what gas is in there. proper care and maintenence will fix most of the problems before they become problems.
Don, you may be 100% right in everything you said. However, I'm not going to run ethanol in any of my motors, and I'm going to continue to pull the same type maintenance on them I have for the past 45 years. Things wear out, and its hard enough to troubleshoot problems without having to deal with that fuel mixture. I'd rather put put than buy a new motor. LOL
E10 fuel has been proven to deteriorate rubber made before 2006. As for finding a eat up accelerator pump in a 2 stroke I doubt it. The things we call carbs on a 2 stroke isn't even a carburetor simply because it doesn't have a accelerator pump. It is called a fuel metering device.
The fuel lines you find on the shelf today was geared to accept the e10 fuel but the kicker was it wasn't made UV resistance. Hence you have deterioration on the outside first with cracks which makes the liner split into little pieces before it starts leaking.. That is why I change all my fuel lines every third summer. E10 fuel is hard on a 2 stroke engine. I try to steer away from the E10 fuels for this reason.
my kit is coming in tomorrow. im also changing my feul lines and primer bulb. have also cleaned my tank out. i always mix my oil and gas 6 gals gas to 16 ozs oil (quicksilver) and impeller was changed two summers ago. should have it together by thursday. i'll let yall know. Thanks all of you.