ENGINE slows down to almost stand still ?

[hamish33]

Hi 

I have searched for this topic but sorry if missed it 

 

Moving along then power drops and just crawls to alm9st nothing 

 

Sometimes fine inreverse sometimes not 

Somet8mesfine in neutral s9metimesnot 

 

Recently refilled fuel 

Was sugges5ed its water in fuel just syphon some out into a obttle and no sign  went to bleed  but fuel coming out of bleed screw straight away

 

Any thoughts ?

 

Thanks 

 

 

[Tracy D'arth]

Prop clear?

Any water in fuel will be at the bottom, fuel filter OK, no water?

What engine? 

[Bee]

Probably fuel but likely to be because of linkages, return springs, or wobbly bits of cable and things. Doesn't sound like air in system

[Tony Brooks]

2 minutes ago, Tracy D'arth said:

Prop clear?

 

Sounds as if it might not be, based on the scant info.

[hamish33]

Hi 

T95 Isuzu thorney croft 2001

Prop clear 

Have just changed gear box but was happening before 

New fuel filters which I hoped  would fix it 

 

Foolishly was looking at the top of the bottle not bottom for water in my sample.....

 

So there is a thin layer of water  as shown in pic I know you can't see it but gives a sense of ratio 

 

Would you empty the tank for that ?

Tips on easiest way to separate the water ...?

When you say things rattling around were abouts should I be looking? 

Cheers 

[Tony Brooks]

Although normally an autumn problem I notice that the trees are already shedding leaves and if there are a lot of them in the water they will pack around the prop but float away the moment you go into neutral. That will give symptoms very similar to your description. However a quick burst of astern tends to clear them for a few more yards.

 

Given time the water in the bottle will drop to the bottom so you can pour most of the diesel off the top.

 

If we assume that you took care to syphon from the lowest point right at the bottom of the tank I don't think it is a bug/dirty fuel problem, but if you took it from the middle or top who knows.

 

I am not very familiar with the details of that engine but:

 

Does the lift pump (be it mechanical or electrical) have a filter/strainer inside it. If so is this clear.

Roughly what volume of fuel issues from the lift pump per single stroke or two engine revolutions - an egg cup is a good measuring tool?

Have you any filters or water traps that you have not found hidden along the line between tank and lift pump?

If you have a CAV water traps/filters then it is easy to get the seals mixed up, misfitted, or twisted. That would allow air to enter the system and the return to the tank may be hiding it.

 

Is the lube oil level going up or is the lube oil very thin and runny, if so it is probably a fuel leak into the sump and the engine may be partially seizing.

 

Regret I can't help much more but photos of your filters and lift pump may help.

 

 

 

[blackrose]

On 09/08/2022 at 20:42, hamish33 said:

Sometimes fine inreverse sometimes not 

Somet8mesfine in neutral s9metimesnot 

 

 

It can't be leaves around the prop if it's happening in neutral can it? 

[Tony Brooks]

16 minutes ago, blackrose said:

 

It can't be leaves around the prop if it's happening in neutral can it? 

 

No, but many years of diagnosis tells me that customers tend to be somewhat unreliable in their telling of symptoms. I am not saying this is the case here, but it may be,

[Richard T]

Another thought - is the fuel tank breather blocked? If it is it would cause a vacuum which will starve the engine of fuel. Its a simple jobe to check and clean. and it the rules out