1997 Merc EFI 225

I recently bought a 1997 Cajun 205 with a 1997 Mercury EFI 225 serial number 0G584136. I've had several issues with the motor since I bought it. When I first bought the boat I could only idle/couldn't get on plane. After getting into the engine we found a coil had overheated and I had it replaced. It started running great for about 2 weeks.

Now, I can't seem to keep fuel pressure. I had the mechanic that did the last fix change the fuel filter a couple of weeks ago and the next day I went out and it was leaking. He sealed it up but since then it's been running poorly. It'll get to about 2500 RPM's but struggle to go any higher. then out of nowhere it'll take off. You can hear it start really revving up and then it just blast off like a rocket. Today I couldn't even get that far. It took off at first, but then the second I pulled back the speed a tad it lost all pressure and stopping running. I primed the bulb but it stayed flat and I couldn't even get to an idle. I tried cranking but nothing. I should also mention that this is all on the starboard side tank. The port side tank hasn't pulled fuel since I bought it. Bulb stays completely flat on that side. Does it sound like air in the fuel lines or something else?

Bump

Start with the BASICS:

-Compression Test
-Spark Test (and confirm correct spark plugs: Champion QL77CC ONLY)
-Fuel Quality, Delivery and PRESSURE TESTS *

*Record pressures:

-At idle
-Under Acceleration
-15/30/60 seconds after engine shutdown.

Well it turns out the starboard side might be user error. The fuel gauges aren't working correctly. I pulled the seat out to look at the tanks and the starboard is dry. Guess they don't run too well without fuel lol.

Still not sure on the port side tank, though. That thing is full but the bulb is completely flat when I try to pump it. The switch I have to use to go back and forth between the two tanks is also kind of tough to turn.

Make sure and check your check valve in the fuel tank. If you can't get your primer bulb to fill with fuel, that is where I would start.

Thanks. I've heard that tossed around a couple of times now. I'm planning on working on it tomorrow or Friday so I'll be sure to post results.

Bypass that switching valve, running directly from the tank to the bulb, and see if the problem ceases.

May be as simple as a bad (or restricted) valve.