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2012 Mercury 90hp EFI Sputtering and Stalling

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Ferg48

New member
New to me 2012 90hp EFI Serial# 1B943073 with only 75 hrs (original) on a Harris Pontoon boat with built in fuel tank.
It has started sputtering and stalling at lower RPM's. Idles fine at dock, but as soon as I reverse from dock and put in gear it starts sputtering like its running out of gas then quits. No alarms. Restarts fine in neutral. If I put in gear and throttle up fast it sputters and hesitates but eventually catches and goes fine at higher RPM's. I've replaced both the low pressure and high pressure fuel filters, but no change. I did notice the low pressure fuel filter only fills about 1/4 full of fuel.
What's next to check/replace? Anti-siphon valve on built in fuel tank? or low pressure fuel lift pump? or change the fuel lines? Looks like fuel line has a piece spliced in by previous owner. It had only ever had premium fuel run in it. Stupid me thought regular fuel would be fine, so maybe I've caused the problem? HELP PLEASE!
 
Ferg48 said:
New to me 2012 90hp EFI Serial# 1B943073 with only 75 hrs (original) on a Harris Pontoon boat with built in fuel tank.
It has started sputtering and stalling at lower RPM's. Idles fine at dock, but as soon as I reverse from dock and put in gear it starts sputtering like its running out of gas then quits. No alarms. Restarts fine in neutral. If I put in gear and throttle up fast it sputters and hesitates but eventually catches and goes fine at higher RPM's. I've replaced both the low pressure and high pressure fuel filters, but no change. I did notice the low pressure fuel filter only fills about 1/4 full of fuel.
What's next to check/replace? Anti-siphon valve on built in fuel tank? or low pressure fuel lift pump? or change the fuel lines? Looks like fuel line has a piece spliced in by previous owner. It had only ever had premium fuel run in it. Stupid me thought regular fuel would be fine, so maybe I've caused the problem? HELP PLEASE!
Click to expand...
Like I responded to the other post on a 90 HP, remove both fuel filters and cut them open. If little black specks are in there that's fuel line degradation. Getting air to replace fuel used from the tank is also a problem when problems develop after a few minutes of running, but you said it will run at the higher RPMs after some sputtering. If your air intake to your fuel tank was the problem your higher RPM running wouldn't exist (opinion).
 
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