Sudden fall in revs in a Volvo 2002

[Graham028]

Hi I hope someone can help with this problem. We were motorsailing back from a very pleasant trip to Rathin Island when after about 30 mins the engine revs suddenly dropped to tick over. Thinking that we had a rope round the prop I knocked the engine into neutral but found that it still wouldn't rev. After checking the fuel system and various attempts to bleed it the revs occasionally rose to about 3000 but then died away. The filters were clean although there appeared to be an air leak in the system. Bleeding the system helped but the revs rose only temporarily then dropped to tick over again

[MARINE ENGINNER]

Originally Posted by Graham028

Hi I hope someone can help with this problem. We were motorsailing back from a very pleasant trip to Rathin Island when after about 30 mins the engine revs suddenly dropped to tick over. Thinking that we had a rope round the prop I knocked the engine into neutral but found that it still wouldn't rev. After checking the fuel system and various attempts to bleed it the revs occasionally rose to about 3000 but then died away. The filters were clean although there appeared to be an air leak in the system. Bleeding the system helped but the revs rose only temporarily then dropped to tick over again

what is the model of your engine?your description is 99% air in fuel system
try to by-pass your filters and start your engine.if the engine doesn't stop is the filters , if stops is hoses , dirty tank , bug in your diesel tank clogging the lines

[Graham028]

Originally Posted by MARINE ENGINNER

what is the model of your engine?your description is 99% air in fuel system
try to by-pass your filters and start your engine.if the engine doesn't stop is the filters , if stops is hoses , dirty tank , bug in your diesel tank clogging the lines

My engine is a 2 cylinder Volvo MD 2002. The fuel seems clean and flows OK from the tank. I'm not sure how to bypass the filters as the lines are copper with banjo unions. I have recently changed the filters and fuel lift pump.

[MARINE ENGINNER]

Originally Posted by Graham028

My engine is a 2 cylinder Volvo MD 2002. The fuel seems clean and flows OK from the tank. I'm not sure how to bypass the filters as the lines are copper with banjo unions. I have recently changed the filters and fuel lift pump.

take a 20lt canister with diesel , 2 flexible hoses length depends your engine position , one for return line and one for supply , place both in the canister and disconnect the old ones and connect the flexible hoses of the canister , it will be like an external tank.

[MARINE ENGINNER]

graham028 sorry my mistake i remembered other type of volvo that is with flexible hoses and not with copper tubes , if you can find any connection that has the same thread on the fuel pump this will help you like the ones that has an air tool and you can connect there your flexible hoses

[Irish rambler]

Hiya Graham, nice run over to Rathlin and back, I've been there many times, my first ever boat(dinghy) was given to me in Cushendall harbour (it was sunk) but it gave me the boating bug when I lifted her. Great fish and chip shop facing the harbour too. Google cruisinginretirement.webs.com. and have a wee look. If your Volvo runs at normal revs then drops it sound like you may have under or over tightened a joint/banjo bolt which allows minute air bubbles to build up until the engine wont run properly, it happened to me and I've seen other engines do it and been really flummoxed until the owner pipes up that he changed a pipe a while ago. Many people tighten the fuel lines too tight thinking they are being prudent and all they need is hand tight and a wee 'nip' to get a good seal.
Good Luck

[Graham028]

Hi

Just an update on my engine problem for those nice people who offered suggestions.
The problem turned out to be a broken spring on one of the injector pumps which is now sorted and the old Volvo is running sweetly again on all two cylinders.