Mercruiser 5.7 efi Ignition problems?

[badal]

Mercruiser 5.7efi 1999 fitted to Bayliner 2655<br /><br />I have recently bought this craft and have been suffering problems since I brought the boat home<br /><br />The engine would only rev to 3800 rpm and was very reluctant to take throttle<br />Initially my local mercruiser agent assured me that the coil was faulty. This was replaced but the problem got worse rather than better.<br />Next a set of plugs was fitted - no change<br />Then the ignition module was changed - guess what - no better<br />He now assures me that the fuel pump is faulty - where will this end?<br />Does anyone have any suggestions as I am rapidly losing faith in the agents judgement<br /><br />I have sourced a pump myself, but it looks like a bit of a job to change - any advice <br /><br />regards<br /><br />Alan

 

[Bt Doctur]

Re: Mercruiser 5.7 efi Ignition problems?

what were the compression readings?<br />you may be down 1 cylinder.clogged injector,restricted fuel flow,initial timing set to specs.dinged prop, incorrect gear ratio in the drive.When you did the water test before purchase did it rev to specs.

 

[Don S]

Re: Mercruiser 5.7 efi Ignition problems?

Is that EFI a throttle body, or MPI? Makes a big difference in troubleshooting.<br />An engine serial number is the best way to go with any marine engine.<br />Sounds to me like your mechanic (agent???) is a parts replacer when you need a troubleshooter.<br />Your problem could be anything from a dirty boat bottom, bad prop, to an ECM meltdown.<br />Lots of fun things to check, and doing the basic tests for water, air leaks, dirt, plugged antisiphon or vent in the fuel system, and timing not advancing, or even needing a tuneup or ??????<br />Anyway, when it's an EFI engine of any kind, there are more things to check, but they need to be checked before starting to throw parts at it.

 

[bigbrownbuku]

Re: Mercruiser 5.7 efi Ignition problems?

leave the spare parts installer, otherwise known as your mechanic and find someone that knows what they are doing.

 

[badal]

Re: Mercruiser 5.7 efi Ignition problems?

thanks everyone for the help so far<br />I was unable to test the boat at wot as there is a 10mph spped limit on Lake Windermere hwere I bought it<br /><br />However I have brought the boat home and will start to carry out all the checks suggested<br /><br />What pressure should the pump deliver fuel at, and what compressions should I expect<br /><br />cheers