triple 525sc back fire problems
 

hello I just upsized to a 42 baja with triples from a 32 baja with twins, I have only had it out a few times and its acting very funny, The port motor has never been apart, starboard has has the manifold off but I dont know what was done, the center engine has a brand new short block from mercruiser. The first day i took it out the port engine was backfiring throught the carb and wouldnt turn over 3000 rpm so I took it home did a full tune up and swapped the two carbs on the back engines, took it back out and the center engine started doing the same, the were all idealing high so i took it in to the dealer and had all carbs adjusted, motors run perfect on trailer, took it out yesterday was out about 1.5 hours of cruzing when I got in a curvy part of the river the starbord engine started doing the same thing for a few seconds then it cleared up, and the center motor started doing it again, i ve changed fuel lines to half inch changed all water seperators. It only seems to do it when your turning but once it starts it want stop , is there anything electrical that is common to all three engines? just dont know what else to do. Can someone help?
thanks
eric

also I am getting some oil sitting on top of the manifold only on right side of the center engine, what could that be. sorry i know its allot but my mercruiser doesnt have any experience with tripples or blower motors, they are the carbed stock 525sc's

i had a 32 with twin 525sc engines,after running for about 45 minutes,the port engine acted weird,sometimes backfire,sometimes die.the cure for my problem was a new trigger unit inside the distributor,hope this helps.:ernaehrung004:

I think it is common to have some oil on the intake. comes from the breather hoes where it enters the flame arrestor from some blowby as a result of the boost
I have 2 525sc's and there is always some oil on the intakes.

not sure about the other issue though, sorry

Ramb

Eathonl / bad gas.......

How many hours on the motors? Also, the oil could be from the seals going bad on the blowers. Hope this helps

Sounds like a fuel problem to me.

525sc
 

thanks guys, i have swapped carbs around and the problem stays in the same engine so I dont think its fuel i will try the the trigger unit, the motors have less than 100 hrs. thanks alot guys for any help i cant stand not knowing what the problem is I hink it has to be electrical

What octane are you running....sounds like bad gas and a lean pop....need some good 93...or a little 110...i'd have someone run a scan tool to see if there are any errors...if it's gas it will eventually be the same on all of the motors and the last thing you want to do is nip a piston....big dollars will ensue...

distributer !!:ernaehrung004: or wires !!

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.