Power loss .....

[PeterM]

A potential puzzle for anyone technical / mechanical

Ran up to Newtown harbour for abit of lunch today - on the way back at 35-40knts and the engine started loosing power (about 4000 rpm) - not misfiring by the sound of it , just not putting power out . Nothing round the prop, or leg & no warings from the gauges - temp/ pressure / volts etc etc all normal . More throttle = less power & throttle back & it runs fine .

Was worried it may be a call for a tow , but made it back fine (just slower). Merc dealer thinks its a fuel supply prob - so new filter / bulb / pipes etc fited in the rain - checked tank - pickup OK . ( I seem to have bust the fuel sender as a seperate issue - typical ! ) .

Oil is fine - defo not guardian mode

Tank full of nice new petrol - tank not cracked/ empty etc.

Any thoughts or suggestions ?

Have to wait till Sat or Sun to test - so listen out for my call for help when it stops completely

Pete

[oujakov]

Seems to be fuel problem. Dirty gasoline and cloged up carb or not enough pressure to supply enough at high RPM.
Try and test method should solve this nuissance.

[PeterM]

A good starting point - probably pulling 35-50 LPH at the speeds it happened. No carbs to worry about on the opti & clean fresh gas ( it looked & tasted ok ! and only filled it last week. )

Just wondering if those in the know agree with the diagnosis, and anyont got a new sender I can stick in it !

[Rodan]

Had very similar on my opti 225 recently. throttled back an all fine - to me it felt like a fuel issue. Looked into it and found a slightly flatened fuel line where i had re-rigged it out of the engine (the angle was too acute). straightened it out, cut out the compressed bit and all back to normal. it was simple fuel starvation - the pump could not draw enough.

[Hightower]

Is there a fuel filter under the engine cover, I'm guessing there is. Has this been replaced?

[PeterM]

Originally Posted by Hightower

Is there a fuel filter under the engine cover, I'm guessing there is. Has this been replaced?

Good question ! If there is I would hope it was changed at its last service in November 08. The main filter/ seperator had a few 'bits' in it , no sign of any water in it or the tank & the bits I dont think were enought to reduce the flow significantly.

Merc dealer didn't even take the hood off - just concerned with tank /main filter.

From what has been said I''l pray its as simple as restrcited flow fro some reason.

Pete

[Steve.N]

This is all very interesting as this is EXACTLY the same issue I'm having on my Suzi Dt55 (see my other thread if interested!)

Yesterday she ran great - then on way back the engine dropped off to 4200rpm and would rev anymore - more throttle - nothing.
We just eased off throttle and she sat at 4200rpm happily - she cruised home not missing a beat - took over 10mins.
I have new fresh petrol and had only changed the fuel lines and filter at start of season - also added a water/fuel separator filter.

This sounds basically the same problem as Blackroady's - I've been plagued with it all season. Why would the engine run ok for a while then suddenly loose power if it's fuel issue??
Is the fuel pump serviceable??

[Steve.N]

Originally Posted by Blackroady

A potential puzzle for anyone technical / mechanical

Ran up to Newtown harbour for abit of lunch today - on the way back at 35-40knts and the engine started loosing power (about 4000 rpm) - not misfiring by the sound of it , just not putting power out . Nothing round the prop, or leg & no warings from the gauges - temp/ pressure / volts etc etc all normal . More throttle = less power & throttle back & it runs fine .

Was worried it may be a call for a tow , but made it back fine (just slower). Merc dealer thinks its a fuel supply prob - so new filter / bulb / pipes etc fited in the rain - checked tank - pickup OK . ( I seem to have bust the fuel sender as a seperate issue - typical ! ) .

Oil is fine - defo not guardian mode

Tank full of nice new petrol - tank not cracked/ empty etc.

Any thoughts or suggestions ?

Have to wait till Sat or Sun to test - so listen out for my call for help when it stops completely

Pete

Pete, meant to ask - Did this happen after a service or after you doing any work on the boat OR was it out of the blue?

[PeterM]

Was totally out of the blue - has been running without fault all year. Nothing changed or tinkered with to cause it. ( Apart form of course the never ending pounding that outboards get on a RIB ! ) I am wondering if it could be something as simple as the primer bulb collapsing & not letting the petrol though.

For me it was all round the rev rev range from 3500 upwards - it might rev to 5k , then drop back , or it might rev to 4200 then drop back , or 5500 then drop off - so not set limit - which seems a little differant to your fixed rev problem.

Like you - no warnings on the guages ( and the smartcraft ones seem to have a warning for everything ! )

Is it possible that there is dodgy petrol around ? Or do all our motors have a sensor that has happened to play up at the same time - but both these would be slim odds given the location of where we buy petrol & you are Suz & me an Opti ............

[Searider]

I had a mysterious drop of 400rpm on my 150 opti. Thought it was a fuel problem and spent a fortune chasing the problem. Turned out to be an HT lead breaking down.

About £60 to change.

[Poly]

Originally Posted by Steve.N

This is all very interesting as this is EXACTLY the same issue I'm having on my Suzi Dt55 (see my other thread if interested!)

Yesterday she ran great - then on way back the engine dropped off to 4200rpm and would rev anymore - more throttle - nothing.
We just eased off throttle and she sat at 4200rpm happily - she cruised home not missing a beat - took over 10mins.
I have new fresh petrol and had only changed the fuel lines and filter at start of season - also added a water/fuel separator filter.

This sounds basically the same problem as Blackroady's - I've been plagued with it all season. Why would the engine run ok for a while then suddenly loose power if it's fuel issue??
Is the fuel pump serviceable??

Stupid question but - is the fuel tank breather open (not blocked)?

[PeterM]

No such thing as a stupid question when trying to fix something like this !

I for one didn't check mine. It 'should' be venting all the time to my under deck tank - but I will blow down it to make sure !

Pete

[jyasaki]

If you can get to your primer bulb while running, try giving it a squeeze or three while throttled up (assuming it isn't collapsed, which would indicate a blockage prior to the bulb.) If your rpms come up, it indicates a fuel delivery problem of some sort. Could be a blockage, a bad fuel pump, quite a few other things. But it will confirm a fuel problem vs something else.

Luck;

jky

[Steve.N]

Originally Posted by Polwart

Stupid question but - is the fuel tank breather open (not blocked)?

I feel stupid asking this - but as this is my first boat I have to:- My tank is a handmade stainless steel unit below the jockey seat/console. I can see the fuel pipe, but can't see a breather???
How does this work as I always assumed that the breather should be closed so when you prime the bulb it pressurizes the systems and forces the fuel through - obviously I'm wrong - can you explain?


Good point about squeezing the bulb when the problem occurs - never thought of that!!

[northseapilot]

That used to happen to me quite frequently when I was in the Navy, was always the HT leads comming off in roughers bit embarising comming along side a fishing boat or into a harbour there you are trying to look impresive and your boats doing 6 knots.

[PeterM]

Just back from the boat - HT leads look secure ( it was very calm when the problem occured) & having blown down the vent its clear. Hopefully it was something now gone - a few quick blips to WOT in the river & it seems OK - may have bust the speed limit slighlty tho !

Steve - when you pump the bulb you are only pressuring the bit between the bulb & the engine - the tank will stay open to vent to the atmosphere to allow the engine to suck petrol through ( if its closed the engine cant pull against the reduced pressure in the tank.

Pete

[hatt11]

Pete,

Completely off topic, am bringing the boat to Christchurch for a few days next week and was wondering whether you could answer a question for me. The captains club advertise moorings do you know if they offer this to passers by looking for a few drinks maybe lunch or is it only for staying guests? Also is there anywhere further up river to stop for lunch? Thanks mate Luke

[PeterM]

Hi Luke - they let anyone stop even if its just for a coffee -. I usually just call them when I am few minutes away on the river. Sometimes they are 'full' , but usually you can squeeze in behind thier resident gin palace. I live within 100yrds and they are pretty chilled out - I go in without shoes & very wind swept if I'm off the boat

You can stop on the quay itself - literally right on the end and go to 'The Boathouse' and still see the boat , or at Mudeford 'The Beachouse' (same owner) - but you will need a tender for that with the boat at anchor.

The only other place to go up river is tuckton tea gardens - great fried breakfast - but in the summer not sure where you can actually stop.

If you need anything or want to stop 'mid river' you are welcome to stop alongside me anytime, or if you want to leave the boat in the water. The ferry cross river can drop you off to the moorings. You cant miss my RIB - opposite slipway (ish) with a hefty 200 on the back ! Only one around that bit of the river

Fair is here next week with fireworks Sat night - so a busy week in Christchurch - just mind the bloody rowers ! In the bilges with that rant !

I'm around Thurs & Friday

[hatt11]

Thanks for that Pete, Ill see where the Mrs fancys going altleast I have a few options!

Spend plenty of time in Christchurch but have never had the time to get the boat out there.

Im policing the fireworks on Sat so should be fun, I was working at the Funday on Sunday which all ended calmly compared to previous years!!

Thanks again, Luke

[PeterM]

So back from probably the best days boating weather this year ( and its only mid August ) , all seems fine again even at max fuel flow of around 78 lph . Maybe its just the time of year for optis to play up ?

Pete