Engine cranks over with plugs out, but not when installed

[cgiesbre]

Hi Nautique Experts - I'm intersted in your diagnostic wizardry. Looking at a circa 1990 Natique with this engine description: "New crate engine with 5 hours on it. New risers and exhaust manifolds. But, had a bad fuel flood due to a stuck carb float. Engine now having a hard time cranking over. Cranks with spark plugs removed. With plugs installed it drains the battery before engine starts. Draws a lot of load and kills battery." Thoughts? Thank you.

[bturner]

I would start by looking first at the wiring in the starter circuit, then the starter itself. Poor wiring and/or a weak starter will give you all kind of starting problems. Poor/corroded connections will draw all kinds of current without providing enough current to the starter to turn over the engine.

Check to make sure the wires are correctly attached for the firing order. This is a sleeper that got me once. If you've had the wires off (which it sounds like you have) then this is at the top of the list to check.

Poor engine timing will give similar symptoms. For that I would pull the number 1 plug to verify TDC (remember there are 2 times the piston is going to be at the top in the cycle. Make sure you're seeing the piston at the top of the stroke during the compression cycle.) then verify the timing mark on the balancer is at 0. Make a reference mark on the engine to indicate where the #1 wire is connected on the cap. Then pull the cap and see where the rotor is. You should be very very close to pointing at this mark. Slowly advance the motor manually until the rotor is pointed at the #1 contact in the cap. You should be able to get a rough idea of where the timing is by looking at the balancer and seeing where the pointer is. You should see something along the lines of 8 - 14 degrees BTDC.

If still no joy, try rotating the engine with a breaker bar on the crank You should feel the compression but still be able to completely turn the rotating assembly over by hand. If still no joy, I would pull the valve covers off and check to see if you have any stuck valves or bent push rods.

I'm pretty much a novice at this and there are probably a lot more talented people on the board that might have a better path to take but that would be how I would start. If the engine ran before without any events, my bet would be in the electrical/starter.

[Rednucleus]

So this was a good runnig engine for 5 hours?

[SilentSeven]

Lot's of red flags; needs some serious diagnostics. Could be a trivial problem (wiring, timing like bturner suggests) or something serious like a carb related fuel washdown scoring the cylinders during break-in. If you're not confident in your ability, I'd refer this one to a pro to have them narrow it up.

Personally, I'd skip the older years and look to get a 93' or new model (all fiberglass construction, no wood stringers) with a EFI system,

[FMSKI]

But, had a bad fuel flood due to a stuck carb float.

Teal boat in Squamish, it's give-away junk status imo but restorable with mega hours and cost. Needs everything, engine, interior, and the wood stringers
Does this mean the motor "hydro" locked up? Possible something is bent up - rods, crank.

We locked up resurrecting a Porsche 928 that had messed up/leaking injectors. The oil pan fills with gas and locks the motor.
We immediately recognized the issue and no damage done.