Crusader 454 troubleshooting question

[Bimmerbill]

Hello all, wondering if you can help out a bit and point me in the right direction. My starboard Crusader 454 started running very poorly at idle on the way back in from a cruise. It almost sounds like its missing, sort of like a Harley motor sound. If I increase the throttle it runs great.

I noticed a strong gasoline smell last night, so wonder if its some sort of ignition issue at lower RPMs. Thinking the coil, but not sure why it would run fine at 1K RPM and up.

Any ideas to point me in the right direction? Boats been running fine all season, it just started acting up.
Thanks,
Bill

[mikeandanne]

strong gas smell and poor idle sort of suggests carb issues----maybe some dirt stuck in the needle and seat would be a start for me and check the float height setting,also a heavy float (gas logged)----that is what I would cross off the list first imo---Mike

[akwalker]

If it is a carburated engine, the first thing I would check for is a choke plate that isn't open completely. With the engine fully warmed up and running, remove the spark arrestor and check that the choke plate is fully open, or in the vertical position. If it isn't, adjust the actuator to achieve this position. If it's fuel injected, the only thing I can think of is a dirty fuel filter to that engine. Good luck.

[Bimmerbill]

Thanks, will check the choke. Its a Q-jet with the spring loaded choke. I cleaned the spring up and lubed it at the beginning of the season. Will take a look tho, thanks!

[Big D]

Yes check the carb. The ignition possibility would be the distributor advance not springing back to idle position after throttling down.

[akwalker]

Thanks, will check the choke. Its a Q-jet with the spring loaded choke. I cleaned the spring up and lubed it at the beginning of the season. Will take a look tho, thanks!

For the record, its not a spring loaded choke. That "spring" is a bi-metal coil that reacts to heat, similar to a thermostat in your home. It is adjustable if you remove the little tin cover over it. The cover is held on by one screw in the center, screwed into the intake manifold. Also, that cover is integral to the choke as it "traps" engine heat, causing the coil to react and ultimately opening or closing the choke plate. If that cover is missing, and the choke isn't opening fully, that could be part of your problem. Good luck!!

[Bimmerbill]

Choke plate goes vertical when the engine is warmed up. It's closed when cold, so I believe the choke is working as intended.

Motor starts and runs fine, but once warmed up idle gets rough and it looses maybe 100 RPM or so.

I put new fuel lines and Racor filters on at the beginning of the season and replaced the carb inline filters as well. I just drained the filter, but haven't started the motor yet.

I warmed up both Port and Starboard and took IR temps of the coils and they were both within a few degrees of each other. I thought the coil may be bad when warmed up and read that it could get hot if bad. I do have a spare that came with the boat that I plan to swap, so hopefully its good.

Alternator seems to be working, but I'll have to unhook the lead to test it so its not attached to the battery. Voltmeter shows 13 to 14v on the dash.

I'll probably take the plugs out tomorrow and check them. They are all new this season. Oil is good, looks like oil and not milk.

Plan to check the distributor advance weights/springs tomorrow as well.

Anything else I can check or any other ideas?

Appreciate the help, thanks!