[Barry33]

HELP !! I had a new Yanmar 3YM30 installed 3 yrs ago, I just now found that the yard did not install a fuel return line to the tank. The motor has run well for 175 hours, but what have I done to my fuel system?

I will fix this in the spring.

Thanks,
Barry

 

[Waltthesalt]

Doesn't compute. The extra fuel has to be going somewhere or it wouldn't run. Perhaps its' teed into the vent line or somewhere that you don't expect. Maybe the yard can tell you.

 

[captbillc]

did you ask yanmar if a return line to the tank is needed on that engine?

 

[TQA]

The fuel return does not have to go back to the tank, just to the inlet side of the lift pump. Look for something coming from the top of the injector pump.

 

[roline]

I've seen several installations where the return line is plumbed back to the filter inlet. That way only the consumed amount is drawn from the tank. On fuel injected gas engines, this is not a good idea if a heat exchanger is not used. The fuel would heat up and require cooling. Don't know if the same issue holds true to diesel applications..

 

[Barry33]

Thanks for the great input...there is really no return line, the outlet is literally plugged.

If I Tee in a return line to the fuel line (between the tank and Racor) do I need to worry about aerating the fuel?

Thanks again,
Barry

 

[tommays]

Well

It clearly works NOW and i would do a bunch of asking Before i did any changing

 

[TQA]

I agree with tommays on this. Look really hard for an alternative return line. All injector pumps have internal leakage. They are designed that way. This needs to be returned somewhere. Although it is possible to do this internally it is usually on an external line. This is diesel 101 stuff. Your installer should have known what he was doing. Hmmm OK he may not, but as it has run for some time without leaks then it is probably OK.

 

[timebandit]

As my old Pappy used to say---------

If it ain't broke, don't fix it!

 

[TSOJOURNER]

If I Tee in a return line to the fuel line (between the tank and Racor) do I need to worry about aerating the fuel?

I would have thought aeration was already going on with cavitation in the pump. Maybe not. You really should get a "release" of some sort on there though. I bet it will run better.

 

[goboatingnow]

I doubt it will run well for the next 175 hours, as the pump is not being lubricated properly

 

[LittleWingCA]

On my Yanmar 2QM15 the return line runs to the top of the fuel filter housing on the engine. Might want to check there also.

 

[stuffinbox]

This doesn't answer your question but, isn't one of the benefits of a fuel-return-to-tank that you can run the lift pump to bleed air from the system without cracking open nuts and leaking fuel everywhere. If the air isn't fed back to the tank, doesn't it just recirculate?

 

[TSOJOURNER]

I never heard of that.

Although I'm a subscriber of "if it ain't broke, don't fix it", I would ask why this wasn't set up. I've never seen a diesel without a return back to the fuel tank.

 

[witzgall]

Have you contacted the yard that did the installation for you, and asked them?

Chris

 

[DwayneSpeer]

Volvo

My old Volvo MD17C did not have a return line to the fuel tank or the primary fuel filter and ran that was for more than 25 years. My new Beta does have one. I installed it.

 

[Barry33]

Again, thanks for all the great input. I'll return to the boat (and the yard) this weekend.

 

[L124C]

HELP !! I had a new Yanmar 3YM30 installed 3 yrs ago, I just now found that the yard did not install a fuel return line to the tank. The motor has run well for 175 hours, but what have I done to my fuel system?

I will fix this in the spring.

Thanks,
Barry

This doesn't make sense. How did you suddenly discover the motor doesn't have a return line? If the new installation was incorrect, the yard has some "splainin" to do. Surely you have addressed this issue with them. What did they say? Are they Yanmar certified? In any case, if there is an issue, they should be fixing it, not you! And you want to deal with it now, not in the "Spring". The longer you wait after you discovered the problem the less legal remedy you are likely to have. I agree with the others that there probably is no problem, but you want to deal with it now, not later. Start with the yard! Your manual should also shed some light on the situation, if you are at all mechanically inclined.

 

[timebandit]

May be the manufacture has designed an internal bypass in the pump so that it can be a direct replacement for a gasoline engine.

Usually, things that can't work, won't work and can't possibly be, don't work from the beginning.

This system has lasted 175 hours.

Although I'm a subscriber of "if it ain't broke, don't fix it", I would ask why this wasn't set up. I've never seen a diesel without a return back to the fuel tank.

 

[TSOJOURNER]

My old Volvo MD17C did not have a return line to the fuel tank or the primary fuel filter and ran that was for more than 25 years. My new Beta does have one. I installed it.

Hey! Just think!.............if you had had a return line maybe your Volvo woulda run for 50 years!:laugher