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Troubleshooting Ignition Problems on a Mercury Outboard
Thread Tools Show Printable Version. Mercury EFI issues Hey all!! Thanks for having me aboard, I came to this place on a referral from a friend of mine. This is my first EFI outboard and I am having a few issues with it that I wish to get corrected, I do have a manual on the way but I was wondering if there is anything I can do while waiting to get my manual.
This is what's going on, but first my serial number 0T If you guys would not mind pointing me in the right direction and giving me a diagnostic starting point that would be awesome, or if you have any questions first that I can try to answer about anything please feel free to ask, again, I am new to this board as well as EFI so please by all means Thanks all!!
Wet plugs and smoke are not unusual, especially when the temperatures are low If you just got the engine used and its an older 2. Do you still have the oil injection on the engine or are you premixing? Welcome to the board. Thank you for the welcome and the reply, I did run a fuel injection service through it when I cleaned the system, I replaced the fuel filters with factory filters, not cheap but worth it,Yes, it does still have the oil injection system in tact.
The injectors should be removed, cleaned and most important, flow checked to know where you are. Mechanical oil injection especially on the 2.
Make sure you have a reputable mechanic remove the injection components and use factory block off on the pump mounting boss. Also, ignition problems are often miss diagnosed as fuel issues on these engines. Nitrofreak thanked for this post.
Originally Posted by Go Time. I imagine finding good marine techs out there in the mountains can be challenging.
Search the threads on this website in the tech section and you will find most topics covered in detail, especially removing oil injection. Will do and again many thanks!!! Have you water tested it yet? Did the PO tell you of any problems? What GoTime said, especially flowing the injectors. I send my to Powers Performance or Brucato.
They both do good work. Remove all oil injection components starting at the pump. Merc makes a block off kit that blocks hole and retains bushing. Very important. Remove module. Remove pressure line from main oil tank the one in the boatremove barb starboard side of motorand plug with pipe plug.
I also like to tdc all holes and mark flywheel accordingly.TexDawg 93, Pilothawk 79, FattyMcButterpants 61, Mark Perry 59, Tritonman 58, Most Online 36, Jan 23rd, Print Thread. Joined: Mar Motor started idling rough and sometimes it hesitates a few seconds when trying to get on plane.
How to Troubleshoot a Mercury Outboard Engine
Joined: Oct Bradshuflin aka hunter'sdad. Joined: May Sounds like you have an injector leaking. Fuel line degradation gets into the injectors and causes them to malfunction.
Could also be the TPS. The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet! Joined: Aug Originally Posted By: Bradshuflin aka hunter'sdad.
Joined: Nov Quit pickin'on 'em Steve! Hes ina deep depression. Joined: Feb Laredo Texas. Honestly, i would just take it to the repair shop and let them take care of it. Originally Posted By: steve scp. Tyler, Tx. My efi started running like that and started getting worse I took it to shop vst pump wasnt keeping full presure all the time.
Joined: Apr I would be suspicious of the high pressure pump in the VST.The engine weight is recorded at lbs. This is a 6 cylinder model. The displacement for the pistons is The bore for this outboard is 3. This engine has power steering and a electric-type starter. For example, if you look at your tachometer at top speed and it is not within the engine's RPM range then that is generally not good.
Be sure to do your testing under your normal boating conditions and with a good propeller not bent, cracked, or excessively chipped. Information on this page is provided to you as a free service of iboats. Because this information has come from many sources we can not guarantee its accuracy.
Even if this information is the same as the original factory specs, boats are sometimes modified. Thus, for safety and other reasons, it is a good idea to verify information here to make sure it matches up with your boat. The iboats Outboard Motor Forums are another excellent source of information.
The iboats Forum Directory can likely help you find a lot of outboard information as it is arranged by subject. Engine Manual: Mercury Outboard Manual Information on this page has come from multiple third parties and can not be guaranteed to be accurate. All rights reserved. This horsepower Mercury outboard, manufactured inis a saltwater model. Mercury Outboard Manual. Information on this page has come from multiple third parties and can not be guaranteed to be accurate.Outboard boat motors are notorious for problems.
To troubleshoot the engine, go through a series of checks for specific issues that can occur and fix as needed. The most common problem with both two- and four-stroke engines begin with the fuel system.
Given this reality, keep a couple of oars handy for if the engine fails while you're out on the water. It also helps to have a citizen's band radio aboard the boat or a cell phone if there is service in the area to contact someone for help if needed.
Mercury Marinebased in Wisconsin, has been making Mercury outboard motors in two- and four-stroke versions ranging from 2. If you have a two-stroke outboard motor, you must add oil to the fuel to lubricate the engine. Four-stroke engines don't need the oil in the engine and are much cleaner machines overall. All two-stroke engines require that you add a specific oil to the gasoline.
The oil-to fuel ratio depends on the requirements of the specific motor. The oil protects and lubricates the engine as well as ensuring a long- life. If you do not mix the oil according to the correct ratio -- which could beor depending on your motor -- you will have problems such as:.
To correct this, empty the fuel tank of all oil. In a clean can containing a gallon of gas, pour in the correct amount of oil. For example, if you require a ratio, each gallon of gas requires 4 ounces of the right oil for the motor mixed in. Foradd 3. Remove and clean the spark plug and replace it before pouring the gas back into the fuel tank.
Improperly mixed gasoline tends to foul the spark plug as well. Some engines -- not the pull-start kind -- have a battery that starts it. If your engine has a battery, make sure it is charged up before use; verify the battery connections are clean -- as corroded connections can keep a Mercury outboard from starting.
Outboard motors require that you start them up and hold the gas until they can idle on their own. Once the motor idles on its own, it is warm enough to operate. Stalling, power loss or excessive vibration generally indicates one or more of the following, depending on the specific problem :.
A fouled propeller requires turning the engine off and cleaning the debris from the propeller. But when the motor runs fine, but the boat doesn't go anywhere, it's likely the propeller isn't spinning due to a broken shear pin. The pin is designed to break instead of the propeller when it contact with debris or a stationary object.Warming up at the ramp it runs on all 6 cylinders, when I leave the marina and slowly get up to around rpm it drops number 2 cylinder. Sometimes it runs on all 6 without an issue but will just drop it the next trip:confused: So far I have 1.
Had all injectors cleaned 2. Checked reeds 3. Swithed coils 4. Checked all earths. Checked for water intrusion 6. The motor only has hrs on it and I am pulling my hair out as most our trips are km return and running on 5 is not much fun and not good for fuel economy.
If I run too long with only 5 cylinders I have to pull the number 2 plug out and replace it as it will not fire back up at all, it ends up a dead plug. The plug just looks wet fouled, not black or sooty. Sorry about the long post but I am hoping you guys will have the answer. Swap switch boxes You have a bad wire or connection going to 2 module.
Check with an Ohm meter while moving the wires. They don't have a "coil" per say, it's a module. I'd be looking at the cdm's and the 2 injector for flooding. The motor should have resistor plugs in it too. Injectors have been cleaned and the bottom 2 were changed with the top 2 when reinstalling to make sure the problem didnt follow.
All other plugs burn perfectly, I will check the harnesses, but I dont understand why the plug fires on WOT and idle and drops when trying to cruise. If it does fire when first getting up on the plane it will run fine for most the day.Mercury outboard running rough - Purging the fuel system - Troubleshooting Part 2
Im relying on you guys: as no one over here seems to know the answer:confused: cheers. Im relying on you guys: as no one over here seems to know the answer:confused: cheers I have seen it only a few times. Most likely it's the vibration that makes and breaks the connection. Only once in 32 years I've seen a linkage rub through and short out a wire as it went by. Your telling me you checked everything but the wiring, so?? Thanks Go-Flight I am taking your advice seriously as I am desperate to fix this problem, I have just removed the cowling to see how to check the harness.
Are you talking about the one that plugs into the coil? If so how do I check it. I was just heading off to bed. Unplug the wire from the coil and look for a bent metel connector or a wire that was crimped without the insulation being removed.
Pull on the wires and see if they come out, just a tug. Trace the wires back to the starting point and do the same. I don't think any of the wires go into a sealed unit.Mercury Marine is an international motor boat company based in Lake Forest, Illinois, providing motors for private, commercial and government craft.
Mercury produces an extensive line of outboard motors. Like all mechanical equipment, Mercury motors can exhibit issues, ignition problems being some of the most worrisome. Many ignition problems stem from electrical issues, but there are a few general troubleshooting tasks you should perform.
Check that there is plenty of gas in the gas tank and that all fluid levels are at the right level. Make sure that all wires are connected properly. If there is no start from the engine, there may be no spark present.
Check that the spark plug for the engine is free of decay and is clean. If there is any water on the spark plug, check for leaks. These are the shorting and short circuit wires. Removing these allows you to troubleshoot the kill circuit.
If the engine starts when these wires are disconnected, then the shorting system is faulty. If the engine does not start after disconnecting these wires, check the purple wire, which is the ignition switch wire, for damage and that it is secured properly.
This will change the engine starting cylinder. If the problem persists in the new cylinder, the stator is bad and needs to be changed.
Share It. Photo Credits.Login or Sign Up. Posts Latest Activity. Page of 1. Filtered by:. Previous template Next. I have a newly rebuilt Mercury efi 3. It may run a little rough for the first 15 seconds and then runs great. I can fish all day without any other problems.
One of my fair boat mechanics here suggested replacing the computer, but that is an expensive guess. Are there thermostats on these motors? Got any suggestions? Tags: None. There are definitely thermostats, I would look at many other options before an ECU. Comment Post Cancel.
I don't have a easily accessable boat mechanic close to me that have that kind of test equipment You checked their operating temperature? It should run around degrees F Does it smoke a lot?
Also when rereading your original post it is a EFI, that would be a 2. If it is a or it would be a 3. The uses Champion Q77CC plugs, if you have your info crossed it could be part of your problem. Thanks for the help. I didn't check the temp in the boiling water Wrong plugs. What is your serial number. Early 2. How cold is your cold weather? In South Florida where our water temperature rarely falls below 65 and can run in the low 90s in the summer, EFIs still need working thermostats to maintain proper low speed operating temps.
If the ECU thinks the motor is cold it will richen fuel mixture to prevent stalling. As a result when the thermostats are partially open which is usually the case the motors smoke,foul plugs, Etc. Or even easier put a new set in. After we get your baseline right plugs, temp, air mixture, and timing then I highly advise running a "shock" treatment of Mercury Quickleen to get the inside cleaned up.