525 Back Fire Threw Carb
 

Has Any Body Run Accross Backfiring Threw Carb Around 3k?wide Open Engine Runs Good And Idle But 3k aint So!sometimes It Sound Like A AUTOMATIC 9MM Gun,pop Pop Pop.drained The Tank Thinking It Was Bad Fuel But The Other Motor Runs Fine!some Help Would Be Real Great!

Re: 525 Back Fire Threw Carb
 

Is it while under a load getting on plane?

A friend had the same problem on his 540's It was bad valves

Do a compression test.

His motor ran fine after he got it up on plane

Mark

Re: 525 Back Fire Threw Carb
 

What motor do you have? How many hours on it?

Re: 525 Back Fire Threw Carb
 

valves was my thought.

Re: 525 Back Fire Threw Carb
 

Check the plug wires for crossfire first before you pull the heads off. Also verify that the plug wires are correctly routed. Don't think the worst until you look at the simple things. Take it from someone who removed the starter from his boat only to find it wouldn't start because it was slightly in gear.

Roby

Re: 525 Back Fire Threw Carb
 

pull the valve covers and check lift especially on exhaust valves
popping usually comes from exh valves not opening or not enough to get rid of spentgases/compression

Re: 525 Back Fire Threw Carb
 

It seems to only happen when hitting a wave!plugs look good!went to havasu for a week and it never happened,only on the ocean!only happens around 3000rpm!Motors only have 100 hrs on them.The boat did have the problem when I bought it with 50 hrs.The boat sat for 3 years before I bought it!

Re: 525 Back Fire Threw Carb
 

Have you changed your water seperators. If the boat sat for 3 years could be alot of condensation built up in the fuel tanks and then being caught in the seperators and starving the motors for fuel at certain times. just a thought

Re: 525 Back Fire Threw Carb
 

I Did Change The Water Seperators Twice And It Does Seem To Get Better But Have Run Boat 50hrs.im Going To Change It Again And Keep My Fingres Crossed! Thanks For The Help

Re: 525 Back Fire Threw Carb
 

Everyone has good idea's of what to check. You may also want to check float level and check for wires rubbing on the edges of brackets and loose wire connections. All these things will give this type of problem. Have seen where wiring coming out of the harness bends around a bracket and are chafed.

If you need any other questions answered or a direction to go in feel free to call the shop.

Pwrbt33- John S.
Offshore Performance
410-827-0200
1-877-GOFAST1

Re: 525 Back Fire Threw Carb
 

Swap carb's,
see if the problem follows to the other engine.

This is a relatively easy check.

jt

Re: 525 Back Fire Threw Carb
 

I had a simular problem on a vortech 350 It would make a loud pop intermitently sometimes like an automatic gun! but would go away and run great! I could not find the problem not in ignition or fuel so I ran it till it gave out. I was turnning about 4200 just as smooth as could be when I heard the fatal pop! On teardown their was nothing left of #5 piston The rod was twisted in two but crank was fine! It had to be a valve sticking! I took the hard way to go as I did not want to pull my heads but that's your choice! my engine had about 600 hours on it and was a 2000 model. good luck

Re: 525 Back Fire Threw Carb
 

If Its Only After Hitting A Wave, Ck The Connection Between The Engine And Harness (usually Hose Clamp To Secure It).
While Running Have Someone Give It A Twist Or Light Pull.
If It Stumbles, Realign Pins And Expand(slightly) And Secure

Re: 525 Back Fire Threw Carb
 

Checked Everthing,could Not Find Any Fuel Or Ignition Problem So I Did Comp Test,found Number 8 Cyclinder To Be Low,pulled The Head Last Night And Found A Burt Exhaust Valve.will Be Back On The Water Tomorrow! :)

Re: 525 Back Fire Threw Carb
 

Now you need to find out why you burnt it. Check your springs real good.

Mark