Re: Sucking sound from 500 EFI ???
 

Birdog, we're still in Raleigh, NC. Sold the 29 (to someone just outside of Cinci, of all places!). Just bought a 35 Lightning Twin Step with a pair of 500 EFIs', sitting on a Myco trailer! Boat only has 115 hrs on it and is like new! Vacu-flush head, refrigerator, fresh water system, bimini, cabin, never used! I'll send you a couple of pictures, when I get some. Do you have your TG up and running? Didn't set anything up for the Lake Cumberland Poker Run this year - too much hassle doing it "remote" from NC. I'll give you a call! :D

Re: Sucking sound from 500 EFI ???
 

Okay, I found the problem!!!!! :D

First want to thank all of you again that took time to respond and offer help. It is very much appreciated. That is what makes this site great.

I put a new IAC motor on, because that was the only thing that had been touched on this motor. It was fine before. Then I noticed a little corrosion around the thermostat housing and desided to pull it and put a new one in and new gaskets.

This gave me the perfect opportunity to pull the plenum off and PRESTO.

What did I find, but two broken o-ring gaskets between the Plenum and the intake runners. They had both split and had a 1/4 to 3/8 inch gap.

Problem solved!!!!!!!!!!!!!

You will need 8pcs. of the Mercury 25-805732 O-rings for the repair.

I will probably do this to the other engine over the winter. Mine are 2002 models and it was time I guess.

Hope this will help some of you guys out that have been sending me PM's with the same problem.

Good luck and thank you all.

Dock

Re: Sucking sound from 500 EFI ???
 

Good job! Did you check the IAC position, and was it low? Just curious.

Dave

Re: Sucking sound from 500 EFI ???
 

Nice Dock! :cool: Has Steel Outlawed checked his??! :evilb:

Re: Sucking sound from 500 EFI ???
 

I called him last night as soon as I found the problem. He is leaving for a poker run tomorrow, so I guess he will not worry with it till he returns.

Re: Sucking sound from 500 EFI ???
 

No, I have not done that yet. I'll be on the water tomorrow and will hook the scan tool up and see what we have.

Re: Sucking sound from 500 EFI ???
 

glad to hear you found the problem, best of luck for the rest of the season !!!!!

Re: Sucking sound from 500 EFI ???
 

Just something else to think about here, when the IAC motor opens it causeing a sucking noise (we know that). When the engine is cold it is open , as the engine warms up, it should close ( we also know that ). When I put the Arizona Speed and Marine larger thoddle body on it was whisling very loud. Spoke to AS&M and they advise me to get the engine to running temp (140 150) and adjust the butterfly open untill the whistling stops. That way the engine is getting enough air that the IAC motor doesn't need to open, and therefore eliminate the whistling sound. I did this and has been fine even sice. I really didn't have to open the valve very much. I only here it now when the engine is cold.

Just FYI...

Hey how hard is it to pull the plenum off? I am having the same sucking noise. If I pull the plenum off do I have to replace the gaskets if I find that they are not bad? Also does anyone know what the torque specs are for the plenum bolts, and is there a certain pattern to follow when you tighten the bolts? Thanks, Mike

It's very easy to pull the plenum. Remove the throttle body, unplug all the sensors, remove the throttle cable, and all the bolts and it pull right off. The gaskets are o-rings so if they are good no you do not have to replace them. I don't know the correct spec for torque, but I just got them tight in a cross pattern while tightening.