mecury 2.5l xri 200 hp efi loss of power

[joemac]

engine serial number 0G167160

engine seems to idle fine. bogs down on hole shot. top speed is reduced about 15 mph. Replaced 3 of 6 spark plugs( all I could get ahold of) verified spark going to spark plugs, checked fuel pressure while on ear muffs thoughout rpm range. no drop in pressure. Compression 100 on 5 and 95 on the sixth. Replaced fuel line from bulb to engine due to crack in fuel line at engine about 6 months ago. replaced fuel filter 6 months ago. I will check tps voltage and regulator screen. Is there anything else I should look at? Am I at the point where I should take it to local shop?

[leonreno]

Check the fuel line from tank to bulb, could be deteriorating on the inside, from ethanol fuel.

[joemac]

I went through and checked the fuel lines. I had a1 rated fuel lines. I cut a piece off to check the condition of the interior and it looked fine. My fuel line from the tank was black a-1 rated and then 1 foot from the bulb it changed to grey blue writing hose. I removed grey hose because I didnt want a extra fittings in the system that didn't need to be there. I tighten up a few other fuel fittings , changed fall spark plugs. motor ran fine on the water. not sure if it was sparkplugs or fuel line. Is it common for spark plugs to go out on these motors? thanks for the help on here. I think I will look into changing thermostat and possibly reed valves as a preventive maintenance item. Is this a dont fix it if it isn't broke item or is it a good idea seeing how they have probably never been changed. I hear alot of storys about sucking a stainless reed valve through the engine.

[leonreno]

Spark plugs don’t usually break but they do get fouled from carbon deposits. One other possibility is the ecu could have some bad drivers that are going out.

[EuropeanAM]

A1 is way outdated- been replaced with A1-15 (tank to bulb) and then B1-15 (Gray w/Blue Stripe 5/16" ID) from bulb to fuel pump inside the cowling. See FAQ Section under "Fuel Lines and Performance Problems"... be careful not to deviate from that at all.

Spark plugs should be considered Annual Maintenance items, if it's been more than a year since they were replaced it's likely that would be a contributor.