If you have the in-tank pump module installed I would strongly recommend you read the article by Richard Martin from "Glacier Diesel Power". I'll quote a few paragraphs from Richards article but you should read the whole thing as there are photo's attached which will make things clear.
"In Closing the new pump appears to be a robust and capable design but it's true potential is hindered by the design of the sender and bypass assembly that connect it to the rest of the fuel system.
The best advice we can give you is to keep your tank above 1/4 full. It won't help the pumps overall output but it will keep the sending units base full at all times and keep the pump well supplied with fresh fuel. "
I ran my tank down to 1/8 to clear out the bio-diesel I'm running. Temps are getting in the teens and it's not easy keeping the bio from gelling so I want to go with straight D1 for awhile.
Long story short. . as the tank got below 1/4 I noticed the pressure occasionally fluctuating below it's normal 14psi. As the fuel level dropped to 1/8 my pressure was down to 10psi with some spikes back up to 14psi. I can only speculate that the fuel sender was starving for fuel and the pump was cavitating. Richards article nailed this right on!
If you have an in-tank pump and no gauge keep your tank over the 1/4 tank mark. If you have a fuel gauge you'll see it happening. Scary! Once I re-fueled. . back to a nice steady 14psi (my system isn't stock).
Mike
"In Closing the new pump appears to be a robust and capable design but it's true potential is hindered by the design of the sender and bypass assembly that connect it to the rest of the fuel system.
The best advice we can give you is to keep your tank above 1/4 full. It won't help the pumps overall output but it will keep the sending units base full at all times and keep the pump well supplied with fresh fuel. "
I ran my tank down to 1/8 to clear out the bio-diesel I'm running. Temps are getting in the teens and it's not easy keeping the bio from gelling so I want to go with straight D1 for awhile.
Long story short. . as the tank got below 1/4 I noticed the pressure occasionally fluctuating below it's normal 14psi. As the fuel level dropped to 1/8 my pressure was down to 10psi with some spikes back up to 14psi. I can only speculate that the fuel sender was starving for fuel and the pump was cavitating. Richards article nailed this right on!
If you have an in-tank pump and no gauge keep your tank over the 1/4 tank mark. If you have a fuel gauge you'll see it happening. Scary! Once I re-fueled. . back to a nice steady 14psi (my system isn't stock).
Mike