2005 EFI 250HP issues

[Mph84]

Hi,

Motor serial is OT997525
250 L
2005 model around 475 hrs
tempest plus 25p

Last couple of weeks I've had a couple weird issues with the motor. It started off as a loss of about 800 WOT RPM's after a long run. It seemed to idle ok but struggled to get up on pad and again very sluggish with lower than normal rpm. When I got home I put muffs on the motor and ran it. I used a inductive spark checker and the number 4 cylinder seemed to have a spark that was not as bright as the rest. When I unplugged number 4 I didn't notice any change in the RPM. It also didn't change when I plugged the coil-pack back in. The other cylinders all dropped RPM and then gained rpm for a few seconds when i plugged them back in. This led me to believe that my coil pack was bad. I got the boat back to the lake Saturday and after a long run the boat started acting up again in the same fashion. Any ideas?? Does anyone know what the pin out would be to Ohm the coil packs?

Thanks in advance!

[FeFanatic]

Did you try to swap coils with another cylinder? Did you check the compression on #4?

[Mph84]

Did you try to swap coils with another cylinder? Did you check the compression on #4?

Compression test is next on the list. I don't have a compression tester so I was waiting to borrow one. As far as the coil, I replaced it and it didn't fix anything... Plugs and wires are next after the compression test.

[Savage]

Does the OLD coil from #4-cylinder work correctly if you install it on a different cylinder? If so then we can determine that it's a possible wiring issue.

[JOE54]

Compression test is next on the list. I don't have a compression tester so I was waiting to borrow one. As far as the coil, I replaced it and it didn't fix anything... Plugs and wires are next after the compression test.

unlikely its a plug wire check they compression then borescope cyl and verify sleeve position is correct

[Mph84]

Checked compression. All are around 120. Fuel pressure was 42. New plugs going in and headed to the lake to try it out.

[JOE54]

QL77CC Champion ?????

[EuropeanAM]

QL77CC Champion ?????

^^^^ ONLY correct plug.

[Mph84]

^^^^ ONLY correct plug.

Yes sir! Gapped to .040. Boat ran great at the lake. I did notice that it didn't ever get up to temp. Ran around for quite a while and temp stayed around 110. I'm wondering if I have a thermostat stuck open. And now wondering if that could cause any of these weird issues???

[EuropeanAM]

Possibly- a cold engine will be a rich-running engine, potentially reducing the life of spark plugs (for that matter, potentially the whole engine).

[Mph84]

Possibly- a cold engine will be a rich-running engine, potentially reducing the life of spark plugs (for that matter, potentially the whole engine).

Replaced both thermostats today. All seems well
with the temps now! What water pressure should I see on muffs??

[JOE54]

2-4 lbs idling

[Mph84]

Thanks for all the help guys! Just fished for 4 days at lake Hartwell and didn't have any issues. My only remaining question is; should I see a drop in motor temp when on pad vs idle. At idle the boat is now running right around the 130* mark. When I get on pad it is dropping to somewhere around 118*. I read somewhere that the poppet valve has a lot to do with cooling off idle. Is that true and is the temp drop something I should be concerned with??

[lpugh]

normal as poppit valve opens with increased water pressure and stats are bypassed.