my baby wont start

[alwayssummer]

my 08 RZ2 is currently stranded in a flooded lake so I guess I have to do this myself.
last season we had a problem where the boat would start, but if I didn't get on the throttle in 10 seconds it would die. put it in the water 3 weeks ago and same problem. after two weeks of rain I went out to start her up and got nothing. ok easy fix, right? new battery and now she'll crank but wont turn over. I've been spending the last two weeks trying to figure this out when I can but the weather out here is not cooperating with me. here is what I've done so far

-fuel filter changed. also no water in the gas.
-fuel pressure is right in spec at 55psi when the fuel pump is cycling before I try to crank it.
-new cap and rotor as of the end of last year. I did check and no moisture inside and still looking good.
-new plugs. which have since gas fouled from me trying to crank it with no spark.
-did check the spark with a tester. hard to see if I got any turning the key and running to the back to look inside. I did get to see a couple of lights on the tester on a couple of the cylinders I checked. side note, today the tester fell in the water and is now 24' below my boat.
-I did check the resistance on the plug wires and most average was 1.7K ohms.
-cleaned the throttle body. heavy varnish inside. was trying to find the IAC which is apparently built into the TPS on my boat.

so now I am currently out of ideas. tomorrow I will try to check the ignition module. I've been looking around but not finding much. so I had to start my own thread. one more question. does anybody know if I can find engine parts at napa or auto zone. I've taken parts in before with little luck. spark plugs, that's about it. maybe if anyone knows of a vehicle that has a GM 5.7L in it. just thinking maybe crank or cam sensor. any help would be great.

thanks guys

[boatwakes]

Sounds like the idle air control valve. When trying to strart, add a little throttle in neutral and if she goes but then dies after its pulled back to idle, the IAC is the problem. It's mounted on the throttle body.

[alwayssummer]

thanks boatwakes. unfortunately, after all the reading I have done, that was the first thing I looked for. My marine power has drive by wire so the only thing attached to my throttle body is the Throttle position sensor and motor. the only thing inside is the butterfly. I cleaned all the varnish off that I could (it wasn't that bad). I have read through every service manual I could find and no luck finding the IAC.

[Z1Fan]

Do you actually have spark? Seems like you have fuel, but no spark...

[alwayssummer]

I went and bought a new inline tester yesterday and checked the #5 cylinder. Spark was there, however there is no way to see how hot it actually was. The coil did check out ok on resistance, so now I'm leaning towards timing maybe the ignition module itself or the cam/crank sensor. Possibly leaky injectors flooding my engine. Still working on it though. The lake rose another foot yesterday.

[Z1Fan]

Just use a new spark plug, it should be noticeable and fairly noisey, your probably just using a HEI plug tester?.

[boatwakes]

Some of the early drive by wire units actually used the throttle plate motor as the iac. Does the throttle plate move when you Use the throttle handle with the key on? See if you can manually hold it open to start with.

[boatwakes]

Which motor do you have? Pictures too please.