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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 2006 Merc 60 EFI BigFoot. It is backfireing and wont

Customer Question

i have a 2006 Merc 60 EFI BigFoot. It is backfireing and wont run under load. It runs fine with muffs on but you put it in the lake and won't make power? Thought it was fuel. Pulled and replaced all fuel lines to up to the Electronic Fuel pump Changed the Mechanical fuel pump changed the 1st fuel filter and housing. Problem still persists. Fuel pressure at the Electronic unit is 42PSI. Any ideas?
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Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with? I see you checked fuel pressure, that is good. Have you also checked compression and spark output?
Customer: replied 1 year ago.
Not sure what compression is supposed to be but did check spark. We are good on all 4 cylinders. Exhaust seems to be normal with no unusual amounts of fuel or color.
Expert:  Jason replied 1 year ago.
Do you want to check compression and get back to me?
Customer: replied 1 year ago.
I got 130 on 1-3 and 125 on #4. Sorry should have mentioned that above. Not sure what they are supposed to be thou. What is factory on them.
Expert:  Jason replied 1 year ago.
Compression would have been 180+ when new. At this point the next step is to have the engine hooked up to a scan tool to read the live data on the engine.
Customer: replied 1 year ago.
Thanks was hoping for a quick fix on this one but had a feeling it wasn't going to be so.
Expert:  Jason replied 1 year ago.
Yeah sorry, I don't think I'm going to be able to help you out with this one.
Expert:  Tan replied 1 year ago.
Hello Pat. My name is***** as a thought have you tried running the engine on a different fuel tank. You could have a fuel starvation issue. You can have good fuel pressure and still have a restriction. A fuel restriction causes a lean fuel condition which will cause backfiring.
Customer: replied 1 year ago.
I went as far as taking the fuel supply line from the connection inside the motor removed it and placed it directly into a fresh tank of fuel to eliminate as many fittins as possible. All lines have been blown as well
Expert:  Tan replied 1 year ago.
Ok then it is time for the engine to be scanned. Looks like you have eliminated all the usual things that the consumer can do without a scan.