1997 Mariner 150 hp EFI

[Vegas-Angler]

I just bought the boat last week and prior to me picking it up the previous owner decided to change the oil filter for me. It was a very strong and clean running boat but now.... When I'm attempting to get the boat on plane or giving it gas just cruising the motor will cut out; like its not getting gas to the motor. I can rev the motor while in neutral and this will not happen, its only when the motor is in gear. Any suggestions??

 

[CharlieB]

Re: 1997 Mariner 150 hp EFI

One or two dead cyls will still rev freely out of gear, yet fail once placed under load.

You need to verify compression and ignition on every cylinder. Tools required are not that many, a spark plug wrench, a compression tester, and a spark gap tester set to 7/16 inch. Remove all the spark plugs and ground all the plug wires except the one you are testing, attach that one to the spark gap tester. Screw in the compression tester and have a helper crank the motor or use a remote starter button. Observe for a hot blue spark 7/16 inch, and write down the compression. Repeat for each cylinder.

If you fail the spark test on any cyl, download the free Ignition
Troubleshooting Guide from CDIElectronics website, study it, then follow the detailed steps to determine what the problem is.

Repost your results and any further questions.

 

[Crawdadblue]

Re: 1997 Mariner 150 hp EFI

He means the fuel filter was just changed. The fuel line from boat to engine is original an old! Its not missing at all only certain times. If it was compression issue it would continously cut out everytime you went to throttle up. Cylinder problem would not be intermittent. Thats why I think its fuel problems. It cuts out only certain times and does not do it consistently. You can give it gas and it will plane out an then full throttle it and it will go an then all of a sudden slow or choke out like its not getting fuel. Thats not a compression issue. I do know how to chk compression it takes literally 15 mins to do compression chk. You can gt compression tester at any automotive parts store like autozone or sears fairly inexpensive and its ez to chk. WE can chk that if you want. Lets change fuel line and clean it first.....

 

[CharlieB]

Re: 1997 Mariner 150 hp EFI

Troubleshooting any problem is best done by an orderly systematic approach to rule OUT things, a process of elimination. Doing simple test as compression and spark don't take much time and besides verifying the integrity of the motor, give an indication of overall motor condition.

Once the mechanical integretiy of the motor and igniton are confirmed THEN we move on to the fuel system.

Granted, obvious potential problems like old fuel lines need attention and can contribute to the problem, an EFI motors fuel system requires a fuel pressure test while under load to verify the high pressure fuel pump is able to maintain pressure at fuel fuel flow.

 

[sschefer]

Re: 1997 Mariner 150 hp EFI

The symptoms you're describing Vegas Angler could have a multitude of causes. Often a bog can feel like a miss and that would normally be an over rich condition. That's just an example and please don't misunderstand it as a possible cause of your problem.

Like Charley so wisely states, it is a process of systematic troubleshooting. Before you start throwing parts at it, get the Mercury Factory Service Manual. These run about 100.00 each but you can find them online for free if you look hard enough.

The service manual is your starting point for trouble shooting any of these problems for the first time. Those of us that know these motors inside and out often make the mistake of not using it and with the advent of online parts purchasing, it can get really expensive really quick.

That's the lecture.. sorry, but if I had listened to that lecture when I first started it would have saved me a lot of money.

Possibitlites for your problem --

Typically a transitional problem like you're having is fuel delivery related. A good cleaning of the fuel system may cure it. However, it could also be an indication of a bad coil ground, a coil that is colapsing too soon and double firing. It could also be a map sensor or a fuel pump. I do not think it is a switchbox, stator, trigger or compression issue but that will need to be determined with testing to be certain.

 

[Crawdadblue]

Re: 1997 Mariner 150 hp EFI

Thanks Steve. I will google bing an yahoo my way to finding the merc service manual online. Also boats.net has diagrams and parts pictures of engines broke down so you can see all the parts and where they go along with MFRs part numbers. Its very cool. I have been in the marine industry for quite some years and have maintained an ability to have an open mind and yes cover all the bases. I think both yall for takin the time to write and appreciate any feedback on this issue. Much appreciated. We are goin to work on the issue today. Starting with recommendations from a couple friends who are both certified mercury mechanics. Clean and check fuel system first like you stated above Steve. So thanks to all for the input and appreciate it very much!