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Engine Power Loss Issues - Any advice?


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Hi folks,

Apologies for yet another post but on the way down the Severn I have had an engine issue. Isuzu 34bhp on a 59' nb.

On the canals from Nantwich to Kidderminster we had a few moment of sudden power loss, which I put down to leaves in the prop, went to Neutral, blast in reverse or two, back to neutrL and then pull away again....apart from a couple of locks full of leaves and debris after the storm this worked well.....

.....sadly this continued with more regular frequency after Kidderminster and more worryingly down on my way down the Severn.

The problem manifests itself in a noticeable loss of power, a much louder exhaust beat and even if I push full throttle it adds nothing. I put it into nuetral and the engine splutters for a while and then after a few moments it settles and regains normal revs on idle, at this point I can then add power and of we go again for between 2 and 4 miles....although it has been with increasing regularity and longer recovery times. Engine really shakes on its mountings when recovering then it settles.

Engine had a full service (supposedly and I have no reason to disbelieve) before I picked it up, I use the stern greaser twice daily and more on longer runs. Oil in engine and gearbox checked & topped up as required (gearbox oil did get lower than I would like but still within guide marks. Fuel in abundance, air filter clean as can be, not checked fuel filter as yet....but before I do that my worry was around the lack of response to the throttle.

On the basis that it is air or fuel, I guess it is now fuel but wondered if anyone had experienced this before I call out an engineer...Not sure if RCR would respond given that I am not stuck and can move in some fashion....not far from Gloucester but holed up awaiting the Spring Tide and the winds tomorrow afternoon so last leg Sunday I guess.

 

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OK thank you - I'm in the bracket of 'A little knowledge is a dangerous thing'- I also had the answer "It's obviously something round the prop or shaft!" - been down the weedhatch so often to no avail that I'm like an F1 tyre changer with the hatch now :D

My confusion on this is that it keeps clearing and given a clean filter less than 130hrs of cruising time I thought ....hoped it would still be clean.

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Just now, mross said:

Or the breather is blocked on the fuel tank.  But certainly a fuel problem.  There may be more than one fuel filter, so follow the line from engine to tank.  If it happens again take the fuel filler cap off and see if it makes a difference.

Cheers mross:cheers:

Used to do this stuff on cars and motorbikes in the 80s but totally loss confidence since computers took over.

BTW - If fuel filler cap off does make a difference,what does this mean?

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4 minutes ago, J R ALSOP said:

I was going to reply but i am loosing the will to live, you have answered  your own problem. A clue:- fuel filter, but keep it to yourself.

Somewhat unkind - but true... OTOH not unreasonable to assume a 'service' would include replacing the fuel filter.

A decently designed boat would have two fuel filters, a primary - hopefully with a  water trap to catch that and any gloop. These don't get changed very often and easy to miss as they tend to be tucked away. It happened to me - so I qualify to answer your question 

https://www.ssldieselparts.co.uk/filter-assemblies-filter-assembly-single-c-267_296.html  

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 - If fuel filler cap off does make a difference,what does this mean?

It would prove that the breather (vent) on the tank was blocked.  This breather is often separate to the cap.  It should have a gauze on it or in it to keek out insects etc.  It will be external and probably near the base of the tiller.

Edited by mross
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2 minutes ago, nb Innisfree said:OP how do you know it's still not leaves,? Stopping prop will allow them to fall away. 

I don't but Gut fell tells me that the current issue isn't consistent with the previous issue and certainly not with the conditions of the river, 

....most importantly, after shifting to nuetral the prop kept turning freely but the engine was spluttering in nuetral, but only when left to calm down did the engine settle again.

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1 minute ago, mross said:

It would prove that the breather (vent) on the tank was blocked.  This breather is often separate to the cap.  It should have a gauze on it or in it to keek out insects etc.  It will be external and probably near the base of the tiller.

Excellent - many thanks again mross:cheers: ...sorry to be a numpty so advice greatly appreciated.

A few beers tonight and I'll get checking tomorrow morning. An external air breather filter would make more sense as fuel has been bought from 4 different suppliers and topped up to the top each time so just doesn't feel right....even though it is now I've said that.

Am used to tracing issues back through in another realm but fuel filter just seemed strange given so recently serviced.

A good excuse for a day off tomorrow ;)

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The very same thing happened to me on the Ouse a few days ago.  Just as we were a quarter of a mile or so of reaching the landing pontoon the power dropped. I kept lifting and engaging the morse control and eventually we got there though it was a bit scary going against the fairly strong flow.  We firstly moored up on the pontoon and then manged to get into the lock but on inspection in the engine bay, there was a small amount of diesel coming from what I now know is the primary diesel filter. I phoned RCR and the engineer came out the next morning and replaced it.  As it was leaking diesel, this meant that air was being sucked through with some fuel.  I think you are well within your rights to phone them if you have a problem which, like me, meant you would not be happy continuing without fixing the problem. Effectively, I had broken down as I could not continue on my journey.

Edited by Nick D
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2 minutes ago, Nick D said:

The very same thing happened to me on the Ouse a few days ago.  Just as we were a quarter of a mile or so of reaching the landing pontoon the power dropped. I kept lifting and engaging the morse control and eventually we got there though it was a bit scary going against the fairly strong flow.  We firstly moored up on the pontoon and then manged to get into the lock but on inspection in the engine bay, there was a small amount of diesel coming from what I now know is the primary diesel filter. I phoned RCR and the engineer came out the next morning and replaced it.  I think you are well within your rights to phone them if you have a problem which, like me, meant you would not be happy continuing without fixing the problem.

Cheers Nick - makes me feel better about phoning them. Have to book my free service so will get my confidence back by knowing what I'm looking at on the engine .....will check this secondary filter if I can find it, I like to try, makes me feel better....provided I don't screw it up :D

nice to know I'm not alone :cheers:

Edited by The Grumpy Triker
Missed last sentence
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Often missed by engine servicers is a wee fuel filter in the electric fuel pump which your Isuzu probably has. Probably behind a bayonet fitting cap on rhe end where the fuel pipes are connected to it. . A fairly common cause of breakdowns.

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1 hour ago, The Grumpy Triker said:

Cheers mross:cheers:

Used to do this stuff on cars and motorbikes in the 80s but totally loss confidence since computers took over.

BTW - If fuel filler cap off does make a difference,what does this mean?

If the engine runs ok with the filler cap off it means a vacuum had built up in the tank holding back the fuel.. Tank breather fault, blocked or whatever. In human body blood circulation lingo, known as a thrombosis.

Edited by bizzard
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Also check any fuel tap cocks like the one at the tank are fully open, Depending on the angle they're installed, they have been known to begin to close under vibration. The ball type that is,  tapered plug cocks are usually too stiff for it to happen.

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24 minutes ago, bizzard said:

Also check any fuel tap cocks like the one at the tank are fully open, Depending on the angle they're installed, they have been known to begin to close under vibration. The ball type that is,  tapered plug cocks are usually too stiff for it to happen.

Cheers Bizzard :cheers:

Fuel taps in and excess drain are both ok but will have to hunt for this little burger of a filter - new one for me so all good learnings :D

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3 hours ago, Nick D said:

The very same thing happened to me on the Ouse a few days ago.  Just as we were a quarter of a mile or so of reaching the landing pontoon the power dropped. I kept lifting and engaging the morse control and eventually we got there though it was a bit scary going against the fairly strong flow.  We firstly moored up on the pontoon and then manged to get into the lock but on inspection in the engine bay, there was a small amount of diesel coming from what I now know is the primary diesel filter. I phoned RCR and the engineer came out the next morning and replaced it.  As it was leaking diesel, this meant that air was being sucked through with some fuel.  I think you are well within your rights to phone them if you have a problem which, like me, meant you would not be happy continuing without fixing the problem. Effectively, I had broken down as I could not continue on my journey.

Not too disimillar to us when we first bought our boat early summer. Big problems starting it - but eventually with lots of cranking it would start and then dying every now and then and just recoverable by putting it in neutral. I knew it was a fuel issue and guessed air leakage but couldnt see any problems. In the end we called out RCR even though in our own marina. They were quite happy to come out and fix it so dont be afraid to call them.

The guy who came spent 2 hours going through the whole fuel line and couldnt find the problem (replaced both filters, checked injectors etc, etc).....till he noticed the nut that connected the pipe from the fuel tank to the primary fuel filter was split, but the split was underneath and only opened up when tightend with a spanner. Never seen that one before.

Get RCR out.

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2 hours ago, Scholar Gypsy said:

Sounds as though it may be worth checking the condition of your fuel as well?  Did the previous owner add anything to kill diesel bug? Is there any water in the tank? 

It was a hire boat previously and no idea how to check for water but the tank was drained on purchase so that I could get two steps welded near the stern while it was out for blacking and the guy is a well trusted sort so if any water then it can only be since and it has been close to full all the time since then.

will get some of that stuff to add in now just in case.....I know it divides opinion but better safe than sorry for the future I guess.

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54 minutes ago, Chewbacka said:

If draining and welding and then refilling the tank, it is possible all the crap has been stirred up and blocked the filters.  Just an idea.

Very True should have confirmed that they would flush it through or a full clean for me....they 'may' have done it but not sure and didn't explicitly ask. Having said that, it has taken over three weeks to show itself so strange in that sense...unless a slow build up.

RCR on the way...will watch closely and going to book their annual free inspection plus add a full service for asap.

thanks again for the ideas :cheers: ...all good learning.

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2 hours ago, The Grumpy Triker said:

It was a hire boat previously and no idea how to check for water but the tank was drained on purchase so that I could get two steps welded near the stern while it was out for blacking and the guy is a well trusted sort so if any water then it can only be since and it has been close to full all the time since then.

will get some of that stuff to add in now just in case.....I know it divides opinion but better safe than sorry for the future I guess.

All sounds good.  I use marine 16

http://www.marine16.co.uk/acatalog/Fuel_Treatment_Range.html

 

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