air in fuel system

[ErikKiekens]

Dear fellow sailors
On my UFO34 I have a Thornycroft 90 (that's some 38 HP 4 cylinders) built 1976 or so.
It was a pain bleeding the fuel system after changing the filters at the start of the season. Now it works, but each time I try to re-start after even one day, it refuses until I bleed the connection to the injectors. Once started, it runs perfectly.
Two years ago I had a similar problem which was then solved by replacing a leaking fuel lift pump.
I have been looking for leaks but haven't found one. Any suggestions?
Greetings
Erik

 

[Caer Urfa]

Had similar problem after replacing two tanks last month and installing new filters.
Try going around every jubilee clip and nipping them up, also check nuts on the filters themselves.
I assume you used pdf tape if you disconnected any pipework, I use Rokol past for all nuts and bolts, sets in 5 hours but bullet proof.
Regards
Mike

 

[TonyS]

Please could you explain
"I use Rokol past for all nuts and bolts"
I have tried googling Rokol and Rokol Paste with no success. Is it a fuel proof sealant?

 

[narooma]

www.rocol.com is probably what you are looking for but there are other jointing compounds available. Depending on where they are to be used (ie threads, face to face metal etc) and what they have to resist (oil diesel water or? 0

 

[davidpbo]

I found an air leak on an Isuzu Trooper by sealing the air intake on the tank (filer cap, removed it and cable tied a polythene food bag over filler spout) I then removed the fuel return pipe and attached a 12V tyre inflator to the section leading to the tank and pressurise it slightly. Fuel dribbled out through a pin hole on the fuel delivery pipe where it existing the tank. If you can't see fuel exiting from a union on the engine side of the pump when engine running, it would tend to suggest air is entering between the tank and the pump and if it is only happening when the engine is left then it is possibly a very small hole indeed.

 

[rob2]

When I bought my boat, the engine had been maintained for years by a "marine engineer". Half hour from the berth the engine slowed and stopped . Over all the years the "engineer" had been changing the oil (for around £200 a go), he had never replaced a fuel hose. The ends had softened and sucked in air at every joint!
New hoses fitted and she starts in spring after a winter lay-up, no problem. Changing the filter, I turn off the supply to the engine and open the bleed screw, gravity does the rest.

 

[Caer Urfa]

Hello Anthony
Sorry about spelling it is known as 'Rocol' oil seal part Z8032
i got mine from http://www.crossling.co.uk/index.htm
But most good plumbing merchants should have it.
It's not cheap £13.49 a tin but very good.
There is a little brush inside the cap and you just paste it over the threaded part of your fittings, tin says 5 hrs to set but I leave overnight to be sure.
PS: Do not spill it on anything.
Hope this helps you
regards
Mike