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Join Date: Dec 2005
08-29-2006, 12:00 PM
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I get a hesitation just off idle when I slowly accelerate. The frustrating part is that it is intermittent although it seems to happen more when boarding/tubing. Sometimes it's slight but other times it is very abrupt and the engine has even killed a few times. The boat's in the shop this week for them to take a look at it. I took one of the shop guys out in it last Saturday and of course it hardly acted up for him. Anyway, just wondering if anyone else has come across this. It's an '05 Mercruiser MPI 315hp with about 55 hours on it (first season). I normally run 87 octane which has about 10% ethanol content.
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Join Date: Mar 2006
08-29-2006, 12:33 PM
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You may have some water in your gas. That's why at the shop it didn't act up, because the boat was sitting level on the trailer. If it comes back "clean" again, jack up the front as high as you can, then put the "fake-a-lake" on there and start it. You should have the same problem now. If so, you should change out the fuel filter, or add water remover. I would change the filter. (Only $7) When doing so, dump the fuel from the fuel filter into a glass cup. See if the fuel separates out into fuel and water.
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Join Date: Dec 2005
08-29-2006, 1:22 PM
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Robb - The demo for the shop guy was on the water. Interesting theory about the water in the fuel. I plan to change the fuel filter when I winterize in a month.
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Join Date: Dec 2005
08-30-2006, 8:08 AM
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TTT - Any other ideas???
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Join Date: Aug 2006
08-30-2006, 9:03 AM
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Check the fuel filters. My wakesetter was hesitating at random times. Turns out it was the fuel filter. I found that my Wakesetter had Two, one on the block, one at the tank.
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Join Date: May 2006
08-30-2006, 10:29 AM
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i too have the same problem on my 05 merc 315hp. had it tested twice by mechanic on puter and came back no problems. drives me nuts, as only down low rpms just off idle , in both forward and reverse. changed out fuel filter and water seperator filter, but still happens, not always but maybe 80% of time.not sure where to go from here, but i think its to do with timing or senser mis-readings
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Join Date: Dec 2005
08-30-2006, 1:52 PM
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Dale - What octane fuel do you normally use? One suggestion I've heard is to use 90 or 92 octane. I normally run 87 octane (per manufacturer's recommendation).
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Join Date: Jul 2001
08-30-2006, 2:03 PM
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This has happened to me too, although it might be a different problem with yours. Mine would on occasion make like it was going to stall when in neutral or when just going forward from idle. For me it turned out to be 2 things: 1) Transmission linkage stretched slightly so when the boat was in neutral the neutral-switch on the transmission was on the hairy edge. Solved by taking up slack in the cable with the adjustment nut where the cable terminates on the transmission. 2) Transmission neutral switch wires worked themselves loose, probably from vibration. I could actually stall my engine for an instant just by pressing on one of the wires. Solved by removing the wires from the screw terminal, lightly buffing the ends, then reinstalling them with a lockwasher. It takes nothing to check these things, and hopefully it will be at least one of them. Trash
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Join Date: Aug 2004
08-30-2006, 2:25 PM
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mine would stall at idle, and at low rpms would hesitate bad. It would neverdo it at the shop only on the water which drove me and the shop nuts. Found to be a small air pocket in the fuel injection line (thanks to Scott Pellaton). 160 hours late no problems (Message edited by ghostrider_2 on August 30, 2006)
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Join Date: Jul 2003
08-30-2006, 2:42 PM
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This is a known problem on Mercruisers. I have read about it on this forum and www.tigeowners.com. I dont remember if there is a fix or not for it, last I remember I dont think there was. Sorry for the lack of info.
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Join Date: May 2006
08-30-2006, 9:55 PM
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paul, i use only 91 octane, so dont think thats the problem, runs fine from low rpm right up to wot, its only at just off idle it hesitates, then runs fine. happens in forward or reverse. i have learned to just deal with it as there seems to be no reason as to why?
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Join Date: Dec 2005
08-31-2006, 8:39 AM
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Kenny - What engine do you have? Also, do you know how they purged the air pocket?
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Join Date: Aug 2004
08-31-2006, 11:04 AM
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same as you 2005 Merc 315 in my 2005 Sanger V215. I don't know how but the shop had to do it, this was after they replaced almost every single thing and were about to replace an engine with 7 hours on it.
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Join Date: Sep 2005
08-31-2006, 5:16 PM
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I have the same problem on my 2005 merc magnum 350 315hp and just about the same hrs (60 hrs) and it to is intermittent, but I've never had the engine stall. Please repost if the dealership finds something.
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