How does the fuel return system work?

[jasco]

Just curious how the fuel return system works. I've switched to an electric pump and at idle I'm only getting about 5 gallons an hour back to the tank. I know the pump is rated at 40-60 GPH so I was kind of concerned about the low return rate. I was thinking that maybe the IP regulates flow back to the return line to maintain feed pressure, but I don't really know. The RV runs fine right now, but I was concerned that this may be a sign of my pump getting weak. Educate me...

Thanks,

Matt

 

[icanfixall]

That flow of 40 to 60 gph is an unrestricted flow. Most of our fuel system is just to cool the pump and injectors but... The flow picks up lots of resistance doing this..... How are you able to know its pushing 5 gph back to the tank...

 

[NMB2]

How are you able to know its pushing 5 gph back to the tank...

he sat there watching it for 1 hour running it into a gas can.

 

[jasco]

I run a two tank WVO system. I'm flushing all the VO out of the system for the winter. My VO tank is a poly tank and you can see the liquid level through the side of the tank. To fill the system with diesel I was pulling from the diesel tank and returning to the VO tank. I let it run at idle for about an hour and I'm guessing based on previous fill volumes that it was about 5 gallons +/- 2 gallons.

I went into it thinking that in 10 minutes I should have 5-10 gallons in the tank and I ended up running for an hour and only getting about 5. It was just a lot less flow than I though I would get, but I don't really know how much it should have.

Matt

 

[MIDNIGHT RIDER]

A healthy return system should cycle 10+ times as much as what gets burned.

What kind of reading is the fuel-pressure gauge showing ??

It reads like you may have a restriction somewhere.

 

[jasco]

A healthy return system should cycle 10+ times as much as what gets burned.

What kind of reading is the fuel-pressure gauge showing ??

It reads like you may have a restriction somewhere.

If this is the case then everything should be ok. I think our engines only burn about 0.6 gallons an hour at idle. So an hour at idle would return 6+ gallons. Should the return system return more fuel with higher rpm?

 

[lotzagoodstuff]

Thanks for the intelligent answer on how you figured what you were getting on the return side. IMHO, I think your system is fine, however, if you wanted to double check, you could measure the fuel tank level, drive around a bit, burning a couple gallons of fuel and double check what you have on the return tank side. I wouldn't worry about any restriction on the return side as I think you'd see a leak and/or have engine stability issues, but again that's just my .02. Two fuel system sounds cool, but I bet you do have to get that outta there this time of year.

 

[typ4]

If you had a restriction on the return side that would do harm the pump case pressure would rise and the engine would just shut off.