Engine power loss

[Azura C/C]

I was wondering if anyone would know why my engine (1998 Mercury 115 Saltwater series)frequently losses power during use and does not seem to accelerate past half throttle or run right after the loss in power. The power loss has occured suddenly under acceleration, during cruising and intermitently in between. Also, after power loss has occured the motor will continue to run, just very rough.

 

[hkeiner]

Re: Engine power loss

There are lots of possibilities and lots of guesses possible. I can not provide a reliable guess with the information you provided so far, but I can suggest that you perform a few basic troubleshooting steps and then report back. Troubleshooting engine bog problems is usually best solved using systematic troubleshooting techiques rather than guessing and replacing parts at random.

1) Squeeze the fuel bulb during engine bog. If the motor responds favorably, you likely have a fuel supply problem. You can then troubleshoot that further.

2) Check for spark on all cylinders during engine bog using a timing light or DVA meter. If the spark is failing on one or more cylinders, you can troubleshoot that further.

3) If the above tests do not highlight any problem, there are other troubleshooting tests that can be done, but I would suggest doing the above two tests first.

Just my thoughts...

 

[Azura C/C]

Re: Engine power loss

I can tell you that squeezing the fuel bulb does not increase revving or rpm's but, pushing the primer on the ignition does yeild favorable results in engine respose when pushed at lower rpm's. I have had fuel issues in the past and have remidied most of them quite easily but, this whole random loss of power has me dumb founded? Also, there should be no spark problem seeing as how the motor has a new stator, voltage reg., coils, wires and spark plugs as of about 10 hrs. ago of run time this season. Although, at this time I am not ruling out anything until I do some further testing. Thanks for the tips though I'll let you know what I can find out.

 

[hkeiner]

Re: Engine power loss

Well, you seem to be narrowing it down some. Since you get a response from pushing the primer and not from squeezing the fuel bulb, your problem is more likely that the carbs are providing too lean of a fuel mixture at low idle speed. Most common solutions include cleaning the carbs, replacing the float valves, adjusting the floats, and adjusting the idle speed jets properly. If you do these things along with a link and sync, you will probably solve your problem.

 

[achris]

Re: Engine power loss

Response with the 'choke', but not with the fuel primer bulb sounds very much like junk in the carb bowl occasionally blocking a jet.... Remove carbs, strip and clean.... Use dry compressed air when blowing out all the passages.

IMHO.........

Chris............

 

[Azura C/C]

Re: Engine power loss

Well it does indeed sound like the carbs from what you fellas are telling me, I know that I had them linked and sync. this spring when I had other work performed but, for all I know the carbs may not have been cleaned since '98 since I just bought the motor last year and have not done any real cleaning on it myself. I will take apart the carbs and give them a good once over and let you all know what I find. Thank-you.