Had the same problem with my 525sc's with bad gas. I did everything you have already done. The fix was drain the tank and new gas. My guess is that motor may have a weak ignition also. I also in the end had to replace the ignition system and the factory box is hard to get. I did this because after the gas issue it would quit when it got hot and finally quit altogether. I ended up using the crane hi6m and never had a problem again. they work perfect and have the 525sc advance curve in them

No ECM on a 525SC to scan.

Check all the basics. About teh only thing all three engines should have in common are the fuel tank supply and the grounds.

Being that its happening in turns, it could be a wire or wires that are chaffed. It also sounds a lot like what my 525SC did when I had water in fuel. Take a water sep filter off and dump it into a glass container. Wait an hour and look for separation. Fuel will be on top and water on the bottom.

thanks bro I tried that and gas seems to look good I have ran about 250 gallons through the tank while having this problem, it will run perfect for about 45 minutes then starts acting up. I really appericiate the information. I have only had stock 454's and no nothing about these blower motors and Im about sick of them.

where can I get the crane hi6m ignition and bout how much does it cost

Try searching on here for them. alot of good info. it might be a good idea if you have one of the motors that is not acting up to try and swap the ignition box with one of the others. its a small black box with i think two square connectors on it that bolts behind the mounting plate at the top left back corner of each engine. kinda fun to try and change if you dont have much room. the crane boxs will be hard to find right now as they are shut down and were hard to get when they were open. lastly dont put out the fuel problem yet. they are very sensitive to bad fuel. i pulled my hair out with this for several weeks and like you said they run fine when your not in the water....same with mine but im glad i only had two and not three...:drink:

There is really not much different on the 525SC's than on regular 454's. The 525SC's are great engines, and I doubt the problem is specific to them being 525SC's.

Probably none out there to be had right now. Crane is closed down for a while.