Thoughts on boat power surge
Submitted by davewillo on Thu, 2021-01-21 11:20
I had my newish boat out on the weekend - 315 Searay with 8.2L freshwater cooled Merc. Planning a trip to GI so I filled up the tank from about half full. Hadn't been out for 6 weeks following shoulder surgery so I took it for a rip from Hillarys down to Scarborough, varying from cruising speed to WOT to clean the hull off a bit. On the way back I had it cruising and suddenly it powered down and then back up again. Did it another one or two times and then ran normally from there on.
Any ideas of what may have caused the issue? Just concerned if I'm planning a longer run. Maybe a bit of moisture or just some gunk going through the injectors? Any thoughts and suggestions appreciated.
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Swompa
Posts: 3871
Date Joined: 14/10/12
Perhaps a bit of shit in the
Perhaps a bit of shit in the fuel? When was it last run or is it brand new?
Did the engine revs change or did it just get sluggish?
davewillo
Posts: 2391
Date Joined: 08/09/16
That's what I was thinking
That's what I was thinking mate. It hadn't had a run for 6 or 7 weeks.
The revs dropped but then almost immediately picked up again. After doing that a couple more times it cruised happily back to the marina. Dropped anchor off the beach and moved around a couple of times squidding with no issues. Just don't want to konk out halfway to GI. That outboard you sold me wouldn't be much use with a 4 tonne plus boat!
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Swompa
Posts: 3871
Date Joined: 14/10/12
Haha! Mate I genuinely
Haha! Mate I genuinely regret selling it!
Struggling to find a good light weight motor for the duck!
Swompa
Posts: 3871
Date Joined: 14/10/12
Haha! Mate I genuinely
Haha! Mate I genuinely regret selling it!
Struggling to find a good light weight motor for the duck!
davewillo
Posts: 2391
Date Joined: 08/09/16
Because I didn't settle on
Because I didn't settle on the boat until late October and had a shoulder reconstruction at the start of December, we haven't used it yet. Will fire it up this weekend ahead of hopefully getting away next week. Sure it'll suit us perfectly!
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Jackalchub
Posts: 599
Date Joined: 10/03/12
May not be of help as this
May not be of help as this was a 200hp 4 stroke outboard issue.. But I had surge cutting out.. and ended up being a high resistance joint in battery isolator circuit.. Eventually failed and I lost trim/tilt - fixed it and surge problem solved. Theory was the joint would fail intermittently, not giving the computer enough juice to run. Didn't spit out any codes.
Just a guess, I have zero experience with inboards
Silver Fox
Posts: 1110
Date Joined: 19/06/14
Check your fuel filters
There's a good chance they're full of crud. 8.2 litres of Mercury big block must be a thirsty beast!.
My wife understands why I clean my rods n reels in the shower....
pelagicyachts
Posts: 1322
Date Joined: 23/02/11
Im thinking along the lines
Im thinking along the lines of Jackal, if it were fuel it wouldnt suddenly recover - it would be a splutterly fall and rise
- i had the same thing happen on my previous 200 series on corragations- turned out to be a cracked battery connector - drop in power and safety shiz kicks in
check your battery(s) condition and connections as a starting point
davewillo
Posts: 2391
Date Joined: 08/09/16
Thanks fellas. I'll check
Thanks fellas. I'll check filters and battery connections. Thankfully lots of room to get around in the engine bay.
Yes it is pretty thirsty beast SF. Quoted at 60 LPH at 22 knots. Not planned as a fishing boat - more of a cruiser that I can fish from. I'll do whiting and squid runs and quite a bit of other stuff if we're at Rotto or GI. Doesn't work out to costly for a weekend away with the wife.
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cruzy111
Posts: 274
Date Joined: 08/10/13
If its got a racor 2020
If its got a racor 2020 style cartridge filter check the inlet side of the filter as well as the filters . There is a check valve ball and spring on the inlet that can get clogged easily with a small chunk of shit out of the fuel tank lines and restrict fuel getting into the filter housing.
sea-kem
Posts: 14959
Date Joined: 30/11/09
Definite process of
Definite process of elimination Dave, start with the simple stuff like fuel as Cruzy says above then move on to electrical.
Love the West!
davewillo
Posts: 2391
Date Joined: 08/09/16
Thanks Andy. I'll get into
Thanks Andy. I'll get into it this weekend and look for the issue. Planning to get out on Monday so I've got time to resolve it hopefully.
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sea-kem
Posts: 14959
Date Joined: 30/11/09
Hope you can mate. My
Hope you can mate. My shoulder crapped itself again today after digging some footings. So bloody busy with work but will have to find time to get it looked at.
Love the West!
davewillo
Posts: 2391
Date Joined: 08/09/16
I had no choice Andy. I
I had no choice Andy. I completely ruptured a rotator cuff tendon plus tore ligaments and the AC joint. Pain was terrible and a cortisone injection only gave me about 3 weeks relief. Still hurts but it's healing so that's okay.
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sea-kem
Posts: 14959
Date Joined: 30/11/09
Bloody hell mate, let us
Bloody hell mate, let us know how you go healing wise.
Love the West!
davewillo
Posts: 2391
Date Joined: 08/09/16
Still struggling with a lot
Still struggling with a lot of pain Andy but that's normal apparently. So long as it works I don't mind!
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davewillo
Posts: 2391
Date Joined: 08/09/16
So we went to GI but got
So we went to GI but got chased away by the wind after 1 night.
Replaced the fuel filter and checked electrical connections and the problem still happened. At first it was only when going over 20 knots but on the way home I couldn't do more than 2,500 rpm or it kept happening. Long way to Hillarys when you can't get on the plane!
May be a dodgy tilt sender as that cuts revs to under 2,000 if it thinks the leg is up. Anyway I'm going to leave it to a mechanic who can use his computer to try and diagnose the problem.
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Coyote_Dave
Posts: 74
Date Joined: 04/03/13
I am aware of a similar issue
I am aware of a similar issue with merc digital throttles - unsure how to fix but could be the culprit.
Or
I have had a similar issue myself and the source of the problem was the fuel line from the tank to the filter which was perished on the inside (outside appeared fine). Simple and cheap to replace in the process of elimination.
davewillo
Posts: 2391
Date Joined: 08/09/16
Thanks Coyote for those
Thanks Coyote for those suggestions. The more I can look at myself or the more suggestions I can give the mechanic the better. Either way should save some $$$
Bloody boats!
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moose hunter
Posts: 64
Date Joined: 14/06/13
Have you checked fuel tank
Have you checked fuel tank breather/ vent & hose?
Jackalchub
Posts: 599
Date Joined: 10/03/12
If the lugs have lost
If the lugs have lost tinning it will have issues.. it's amazing how good a connection can look.. (12v) but still cause dramas. Sometimes bridging them out 1 at a time is the only way. Once again this is only information.. not assumption of cause. I'm still in hospital and very foggy from meds too. Good luck dave
davewillo
Posts: 2391
Date Joined: 08/09/16
Thanks Jack and Moose. Hope
Thanks Jack and Moose. Hope you're on the mend soon Jack. Those bloody painkillers they gave me when I got my shoulder done in December really messed with me. Hope you fare better!
I'm getting it looked at this week as I don't have the time myself and I still struggle in tight spaces with my shoulder. The mechanic also suggested that it could be perishing in the fuel line internally like Coyote_Dave did. I darined the filter again on Saturday and the fuel had black crap in in it so I definitely think it's fuel. I'll let you know what he comes back with.
Thanks again for all the advice fellas.
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davewillo
Posts: 2391
Date Joined: 08/09/16
Okay an update after having
Okay an update after having the mechanic look at it.
I got a full service done and a couple of small jobs but the likely issue was fuel. Unbeknown the me the filter I changed was the primary and there is a two-piece filter in the fuel module, which also cools the fuel prior to delivery. I could have found it I guess but the fact that it also connects to seawater would have made me a little nervous in case I stuffed it up. Plus ai wanted a full servous and idagnotic check.
Anyway the filters were full of sludge so he thought that would be the problem and it was. Took it out yesterday and ran like a dream!
Thanks for all the advice fellas!
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sea-kem
Posts: 14959
Date Joined: 30/11/09
That's a good outcome Dave,
That's a good outcome Dave, especially when the problem is obvious.
Love the West!
Swompa
Posts: 3871
Date Joined: 14/10/12
Good to see it was
Good to see it was relatively simple!
davewillo
Posts: 2391
Date Joined: 08/09/16
Yeah I'm pretty happy that
Yeah I'm pretty happy that in a process of elimination it was found early!
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