P38A Spill off pipes.

'Morning all,
spill off pipes leaking again! Thought I had them sorted and then another one goes. Question is - might there be a pressure build up? should I be able to blow through the return pipe to the tank? (ie is it just an open pipe?) And why does it go to the banjo on the FIP first?
Thanks for help

plumbfisher said:

'Morning all,
spill off pipes leaking again! Thought I had them sorted and then another one goes. Question is - might there be a pressure build up? should I be able to blow through the return pipe to the tank? (ie is it just an open pipe?) And why does it go to the banjo on the FIP first?
Thanks for help

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No you cannot blow through to the tank. As you have noticed, the leak off fuel is returned to the FIP.
Most of the leak off pipe sold is not long lasting. The recommended stuff is from Gates, it has woven reinforcing in the rubber, most of the pipe sold for leak off's doesn't have this.

Thanks Keith,
So is it possible that there is a pressure build up, or does the FIP take in the returned fuel, according to throttle position, and then any excess returned to the tank?

plumbfisher said:

Thanks Keith,
So is it possible that there is a pressure build up, or does the FIP take in the returned fuel, according to throttle position, and then any excess returned to the tank?

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Excess fuel is returned to the tank from the FIP. I'd be surprised if there is any pressure build up in the leak off pipes unless there is a duff injector. Only relatively small amounts of fuel should be getting into the leak off line. Take the cap off the spigot on injector #6, attach a pipe, other end of the pipe into a bottle, start the engine and look at the flow you get.

This is the number of the Gates pipe
GATES 3225-00070

Thanks again for your help. Gates pipe ordered. Haven't done the flow test yet, don't know really how much I should expect to get. Presumably it increases with revs. Can't think there's a duff injector 'cos it runs smooth and sweet (even when ****ing diesel!)

plumbfisher said:

Thanks again for your help. Gates pipe ordered. Haven't done the flow test yet, don't know really how much I should expect to get. Presumably it increases with revs. Can't think there's a duff injector 'cos it runs smooth and sweet (even when ****ing diesel!)

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As the leak off line connects to the fuel input banjo, you should get a steady flow, maybe, never tried it so not sure.

Don't forget the injectors have two exit points on the top.
You'll need to block one while allowing each injector to give a flow result.
They should all be a small amount and reasonably similar and all tested at the same time.
Any one injector with very little or no fluid is usually jammed open.
Any injector that gives out more than the others can be sticking internals or blocked. But if it ticks over with no smoke and runs well at different engine speeds they could be OK. The older units are far more robust than the modern overly complicated and hard done by injectors.
Don't forget to block the tube connected to the fip as it will leak also.