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triple 525sc back fire problems

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Old 03-23-2009, 10:28 AM
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Default 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?
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Old 03-23-2009, 10:31 AM
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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
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Old 03-23-2009, 11:03 AM
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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.
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Old 03-23-2009, 12:58 PM
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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

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Old 03-23-2009, 01:43 PM
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Eathonl / bad gas.......
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Old 03-23-2009, 02:17 PM
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Quote:
Originally Posted by louielouie2003 View Post
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
How many hours on the motors? Also, the oil could be from the seals going bad on the blowers. Hope this helps
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Old 03-23-2009, 03:11 PM
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Sounds like a fuel problem to me.
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Old 03-23-2009, 09:10 PM
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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
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Old 03-23-2009, 10:52 PM
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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...

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Old 03-23-2009, 11:02 PM
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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
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