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Mercury outboard 115/80 Jet Sputtering Issue

J

jetguy52

New member
Hi Guys,
I have a Mercury 115/80 outboard jet with Big Tiller. Serial#2B805424 with 119 hours on it. I have had the boat for 2 years with no issues until recently. I was driving back and nearing the dock when I ran out of fuel. Put new fuel in, primed bulb turned key on and off a few times to prime and cranked right up. Next time out, after about 6-8 minutes of driving 3/4 to max RPM the engine started to sputter. I took it to my mechanic and we changed the following with no success. The motor will start, idle and run fine below about 20mph. After running max rpm for 6-8minutes it will start to sputter. I am not sure the running out of fuel has anything to do with this or if it is coincidental. Below is a list of what has been changed so far.
-Fuel Filter, (both)
-Fuel Lines
-Prime Bulb
-Flushed tank (Aluminum tank)
-New low pressure pump
-New Spark plugs
-New oil change & Filter
-Water pump
-Spark plug wires & Coils
-Also tried running it with trim sensor unplugged but no change occurred.

After this I hooked it up to dealer computer and engine showed no codes or faults. They told me to run the engine and see if any codes appeared while doing so. I ran the motor using my vessel view and engine threw no codes while sputtering. RPM max was 5,750-5,800, fuel pressure was 40ish, engine temp was 136. Everything appears to be fine and engine is not throwing any codes. At this point the mechanic, dealer and myself are stumped. Any ideas or troubleshooting we can try? It sounds as if someone is turning the key on and off while i am driving and it only occurs at the 3/4 to max throttle range. Other thoughts are kill switch, neutral safety switch?

T.I.A.
 
Did you ever think that bad fuel could be your problem? I do! In looking at the list of things you did I didn't see a mention of draining and replacing the fuel with known good fuel. Sputtering to me sounds like something floating around in the fuel that comes and goes causing the sputtering which to me are power impulses coming and going due to fuel not igniting, or not being able to ignite properly, or explodable fuel not getting where it needs to be.
 
Texasmark said:
Did you ever think that bad fuel could be your problem? I do! In looking at the list of things you did I didn't see a mention of draining and replacing the fuel with known good fuel. Sputtering to me sounds like something floating around in the fuel that comes and goes causing the sputtering which to me are power impulses coming and going due to fuel not igniting, or not being able to ignite properly, or explodable fuel not getting where it needs to be.
Click to expand...
Also ran it off separate tank and same issue occurred. I failed to mention that in first post.
 
The rev limiter is about 1" square and is on the Port side of the engine down low, just above the cowl. Black with yellow stripe, purple, brown plus a ground via the case.
 
Thanks Texasmark. I will check that this evening. I ran boat yesterday with vesselview to check oil pressure and i also adjusted the liner inside the jet housing. My rpms are now 5,600 at WOT and im getting 2-3mph more out of it but engine is still doing same thing. Have also heard of a neutral safety switch issue?? I will try uploading video of motor. Thank you all so far.
 
Texasmark said:
The rev limiter is about 1" square and is on the Port side of the engine down low, just above the cowl. Black with yellow stripe, purple, brown plus a ground via the case.
Click to expand...
Had a brain fart: Port is the left side of a vessel, Starboard is on the right. The location of the module is on the Starboard side, not Port. Sorry about that.
 
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