2008 Precedent dieseling

[CP241]

Originally Posted by lockman1

I'm finding it hard to believe that it may be an electrical issue,*
But, I don't know Precedents like David does, so I'll take his word for it!

I concur!

Let us know what you find

[Warato1]

Thanks for the parts list, Lockman. Electrical may be the wrong word, David believes the coil maybe bad/wrong causing a spark/timing issue.

I hope to do to test the coil like David suggest tomorrow afternoon. I did some more looking this afternoon and it seems someone has spliced the green wire on the micro switch and ran a wire directly to the solenoid. I'm not much for wiring so I'm kind of lost on why the did it and what "problem" they may have been trying to remedy.

Does anyone know a way to test the timing without pulling the flywheel cover?

[lockman1]

Just curious... what did your old spark plug look like when you changed it?

Black and sooty? (rich mixture) or gray (lean mixture)

The reason I ask is it's fairly common to have excess carbon on the cylinder head, and that causes dieseling,
there's a pretty simple fix for that...

[Warato1]

The threads where carbon and the electrode gray/white. The motor is running extremely hot after about 1.5-miles.

I cleaned the carb and added a little seafoam to the gas, then went on longer run about 5 miles and the lifters started tapping. I have cleaned the air box out add new filter and removed the exhaust and pulled the fan shroud to cleaned it out and the engine still runs extremely hot.

I'll take any advice your willing to share.

[lockman1]

If the plug was sooty, you put a 1/2 oz. of Seafoam in the spark plug hole, reinstall the plug without connecting the wire,
turn it over for about 5 seconds to spread the Seafoam around in the cylinder, then let it sit for 1/2 hour or so...
reinstall the plug wire, and start it in maintenance mode, and run it at medium RPM's until the smoke clears.

That usually clears the carbon, and stops the dieseling.

[lockman1]

It's a bit concerning if the rockers started tapping!

[CP241]

Originally Posted by lockman1

It's a bit concerning if the rockers started tapping!

It's a lot.comcerning if the rockers started tapping. I would not run the engine until you figure out why. Precedent *should* have FE350 which *should* have hydraulic lash adjusters (HLA) and the only thing that would cause tapping is if one collapsed, or if something else I'd making noise.

I have seen whrte earlier precedents had FE290's and I have had FE350's with manually adjustable rockers. So anything is possible but I'd be doing some digging...

[lockman1]

Originally Posted by CP241

...and the only thing that would cause tapping is if one collapsed...

It' not the "only thing", but it is the most common.
Over-reving will float the valves and cause the rockers to tap also! (Don't ask me how I know that!)

[CP241]

Originally Posted by lockman1

It' not the "only thing", but it is the most common.
Over-reving will float the valves and cause the rockers to tap also! (Don't ask me how I know that!)

[Warato1]

Tried the Seafoam trick it smoked for about minute and cleared up. I didn't have time to ride it around the block to see if it would diesel.

I agree the rockers tapping is concerning that is why I have been trying to determine why it is over heating. Any ideas what would cause it to over heat, I have already cleaned the fins and fan.