Thornycroft engine problem

[pfrank]

Good Morning Everybody
I rely need help with my Thornycroft 90 engine it is like BMC 1.5
Recently I purchased Moody 333 and have no means to check engine while boat was on hard, but after lunching yesterday I run the engine and after abound 10 minutes it revs up and dying, next it is difficult to start but when it start again it running for 10 min. revs up and stops. It going over and over again.
I bleed system and it seems that fuel is reaching injectors.
Can anyone have idea what it cud be
I will be very grateful for any advice soon have to move boat from present mooring
Paul

 

[sailorman]

sounds like fuel starvation.
have you checked the filters
if filters changed ( CAV type ) did you change the sealing ring in the filter head

 

[Cliveshep]

I had the same symptoms, usually just as you are coming to a particularly delicate manouver suddenly the engine takes it into it's head to scream its nuts off causing sudden increase in speed just when you want to slow down, then, having speeded up the boat and whilst you are frantically trying to get it to go astern the pig dies completely.

Usual problem is fuel starvation caused by a massive airlock. These engines mostly have a rotary fuel pump which is an absolute swine to bleed out. You just have to bleed the system right through very carefully, and check all connections first as air leaks are a particularly sensitive issue, the slightest fault allowing air to get sucked into the injector pump where it remains. Then loosen each each injector pipe and ensure fuel is bleeding through the injectors whilst you spin the engine over on the starter.

Naturally before you start ensure the filter is clean and properly sealed down. You just have to grit your teeth and stay with it as they do not bleed easily, you think you've got it then when you loosen the injector banjo and spin the engine over to check lo and behold the bugger is dry! That's the only way to make sure the pump is clear, open the injector banjos and let fuel bleed out.

 

[pfrank]

Yes I changed fuel filter and sealing ring ( not sure right model of filter)
Cud it be not properly bleeding of system ?
Thank you for replay
Paul

 

[pfrank]

Thanks for proper replay
You save my day because I suspected more seriously problem involving faulty fuel pump but now it for me looks like not properly dan bleeding of system
Thank You
Paul

 

[Csail]

On mine it was a big airleak on the fuel hose.