Mercruiser only starts with starting fluid

[Vettedrmr]

No, you'd need to take the boat to a marine shop with Mercruiser scan tools compatible with your boat.

[BrennanB]

Ok thanks. I called Texas tige to see if they could test it and they said no. But they also said it most likely isn’t that. Most likely flipped spark plug wires (I’m pretty sure they are in right order) or a ripped plug wire.

[Vettedrmr]

If "Texas Tige" is referring to the manufacturer, yeah, I doubt they'd have the diagnostic tools on hand for a boat as old as ours. If you're in the North Texas area, you could reach out to NXTLVL Marine in Fort Worth. I know they've got the equipment (well, they did back in '23).

However, I will say I've embarrassed myself more than once on ignition systems. I'd go back and check the wiring One. More. Time. Also, check for loose plug wires. I don't expect that, since you had the problem before and after you changed out the plugs, buuttttt.....

[BrennanB]

I replaced plug wires and it did not fix. It only does it under load. And definitely does it throughout rpms (can’t hear it as well over sound of motor). I’m kind of stuck in it being injectors. Thought?

[BrennanB]

I replaced plug wires and it did not fix. It only does it under load. And definitely does it throughout all rpms (can’t hear it as well over sound of motor). I’m kind of stuck in it being injectors. Thoughts?

[BrennanB]

FIXED!!! It was the timing.

Loosened the 10mm bolt at the base of cap and rotor and turned it clockwise till it got better. Couldn’t really tell but it wasn’t even giving it the full power the whole time.

[Vettedrmr]

Outstanding!!! Did you adjust the timing while on the lake?

[boatwakes]

What year is this thing? Where are we with the ignition module???? Replace it if its the two wire unit. Timing doesn't just change so I'm pushing again to change the ignition module then reset the timing using the correct method. The engine must be put into base timing mode, there's a thread here on how to do that with the Thunderbolt distributor ignition, and then set to 8* BTDC at idle. The ignition module adds timing throughout the rpm range so if it was malfunctioning it may have been adding too much timing in that rpm range. USE A TIMING LIGHT TO GET IT RIGHT!!! They're $55 on Amazon.