Vetus engine rough above 1800 revs

[Rivelin]

Hi all,

 

My Vetus M4.15 runs nicely all day at 1500rpm (which gives me ~4mph), but if I push it above this (when I'm on the large rivers) it starts to run rough. If I take it over 2000rpm it stutters any will cut out if I don't drop the revs back to 1500 or below.

 

I recently completely filled the tank and it can now manage higher revs before running rough.

 

Do you think I need to sort out water in the bottom of the tank, or does anyone know whether injector problems could give this problem?

 

Many thanks in advance!

 

 

[Boater Sam]

If there is the usual electric fuel pump, have you changed the filter in the bayonet cap end?  They get missed and block.

 

Injectors won't do this.

Check your prop for rubbish, its surprising what that will do.

[Sea Dog]

I suspect, because things improve a bit when you fill the tank hence increasing the head of pressure at your tank take off, your fuel supply is restricted in some way. Clogged filter, dodgy pump, too small a pipe (if it's done it from new)? 

 

Edited to add: your fuel cock is fully opened, right?

Edited January 15, 2019 by Sea Dog

[Rivelin]

Thanks folks.

The fuel cock is fully opened and the prop is clear. I haven't ever checked the filter in the bayonet cap end though, so that's something I should do!

I'm not sure how I should determine if any of the supply pipes are too small - I kind of assumed that as Vetus is built on a Mitsubishi base they would be fine. I shall dig out my micrometer and do some measuring (external dia only!)

[WotEver]

1 minute ago, nickhindle said:

I haven't ever checked the filter in the bayonet cap end though, so that's something I should do!

Definitely. They fill with sludge very quickly. I used to have to change mine twice a year. 

[Sea Dog]

Just now, nickhindle said:

I'm not sure how I should determine if any of the supply pipes are too small - I kind of assumed that as Vetus is built on a Mitsubishi base they would be fine. I shall dig out my micrometer and do some measuring (external dia only!)

I was referring to the supply pipes fitted by someone who didn't consider them correctly at the boat build - rather than those on the engine itself, which certainly ought to be right! Too small a pipe is a long shot though, so the last thing to check and only if there's been a problem ever since new. My money is on something restricting the fuel flow to the engine for reasons explained earlier, but most likely it's muck!  I have had an issue with a valve that looked fully  open and wasn't as the handle and valve body were no longer aligned. How old are the flexible pipes?  Are they perhaps old enough to have gone soft and swollen inside?  If you haven't been carrying out your own maintenance and don't know how new the filters are (and perhaps even if you do!) the first thing to do is change them to get yourself at a known servicing baseline. Start with the easy stuff.

[mrsmelly]

I would bet money on it being gunged up filters. Probably all of them. Dont forget the tiny one in the fuel pump. My vetus did exactly that until I replaced all and cleaned through.

[ditchcrawler]

With the comment aits better with a full tank of fuel I wonder if its a small air leak on the primary filter when the pump is sucking the fuel up, with a full tank it may be positive pressure, or even the pump its self

[Mad Harold]

33 minutes ago, mrsmelly said:

I would bet money on it being gunged up filters. Probably all of them. Dont forget the tiny one in the fuel pump. My vetus did exactly that until I replaced all and cleaned through.

Yes, agree completely.

[WotEver]

43 minutes ago, mrsmelly said:

I would bet money on it being gunged up filters. Probably all of them. Dont forget the tiny one in the fuel pump. My vetus did exactly that until I replaced all and cleaned through.

Mine was the same. 

[Rivelin]

Thanks all, about to order new filters all round ?

[Tony Brooks]

Personally I would fit a proper primary filter in the pipe run and throw the idiot one in the pump away.

[Rivelin]

I assume that would be more effective as I could use a nice big one?

[Tony Brooks]

8 minutes ago, nickhindle said:

I assume that would be more effective as I could use a nice big one?

Not so much more effective filtering wise but being larger far less prone to clogging, espevciay if you got one with a coiled rather than pleated element. It well also act as a water trap as well.

[ditchcrawler]

45 minutes ago, nickhindle said:

Thanks all, about to order new filters all round ?

Buy 2 sets so you have spares 

[Guest]

3 hours ago, Boater Sam said:

If there is the usual electric fuel pump, have you changed the filter in the bayonet cap end?  They get missed and block.

 

Injectors won't do this.

Check your prop for rubbish, its surprising what that will do.

Seconded. Our Vetus ran like a bag of spanners until I discovered this filter. RCR guy told me most Vetus breakdowns are the fuel pump filter.

Edited January 15, 2019 by Guest

[dor]

When you change the filter on the end of the pump, be careful not to drop the rubber sealing ring. Also, make sure magnet is centred when replacing.

Almost certainly the cause of your rough running.

[Rivelin]

Thanks again to all - some great tips ?

[Mac of Cygnet]

Do all Vetuses have this fuel pump filter?   Mine is the smallest, 2 cylinder one and I've been boating for 14 years (6000 hrs) in blissful ignorance of such a thing.  Do I have one?  I don't remember seeing it in the maintenance schedule in the handbook.  I do religiously change the other two fuel filters, though.

[Boater Sam]

If you have the electric pump, yes.

[dor]

1 hour ago, Mac of Cygnet said:

Do all Vetuses have this fuel pump filter?   Mine is the smallest, 2 cylinder one and I've been boating for 14 years (6000 hrs) in blissful ignorance of such a thing.  Do I have one?  I don't remember seeing it in the maintenance schedule in the handbook.  I do religiously change the other two fuel filters, though.

If you have a decent filter before the pump it could well keep clean enough to survive.  If you get much in the way of dirty fuel it can get clogged.   I don't change mine as often a i do the primary filter, unless I've picked up some muck or diesel bug.  It is easy enough to change, but don't pay the ridiculous Vetus price for the filter, you can get a Baldwins one for a fraction of the price from e.g. inlinefilters.co.uk.

[bizzard]

Often mounted vertically with the bayonet cap at the bottom, you may have to dismount the pump to get at it properly. There should also be a light spring inside which keeps the filter seated and pushes on the cap to keep the bayonet pins engaged.

[OldGoat]

22 hours ago, nickhindle said:

Hi all,

 

My Vetus M4.15 runs nicely all day at 1500rpm (which gives me ~4mph), but if I push it above this (when I'm on the large rivers) it starts to run rough. If I take it over 2000rpm it stutters any will cut out if I don't drop the revs back to 1500 or below.

 

I recently completely filled the tank and it can now manage higher revs before running rough.

 

Do you think I need to sort out water in the bottom of the tank, or does anyone know whether injector problems could give this problem?

 

Many thanks in advance!

 

 

Now that the probable immediate cause of the rough running has a solution, Is it now time  to address the above highlighted comment?

It's always a good idea (or even an essential one) to test the fuel at least annually for water / gunge / whatever.

Amazon have a selection from around a tenner, or you can get a yucky siphon jobby  for a fiver.

[Rivelin]

I was just checking for serial numbers / model numbers etc. and there's what look's like a filter housing on the diesel return line. This isn't in the manual, so I'm not sure what it is and whether it contains a filter that should be changed along with the others?

[Jen-in-Wellies]

25 minutes ago, nickhindle said:

I was just checking for serial numbers / model numbers etc. and there's what look's like a filter housing on the diesel return line. This isn't in the manual, so I'm not sure what it is and whether it contains a filter that should be changed along with the others?

Photo?