Diesel fuel tanks

I just moved from a class A to a diesel pusher. It's a 97 Monaco Windsor. When I fuel up I have a large amount of vacuum in the tank. Could I have a vent line plugged or is this normal.


Senior Member
Re: Diesel fuel tanks

Where do you fuel? If I use the large nozzle/high speed pumps for 18 wheelers, it does not work well unless I just dribble it in at the lowest speed I can manage. Using a standard nozzle and speed (like at Flying J's RV island) works fine.
Re: Diesel fuel tanks

The vacuum is as I unscrew the cap. If I'm 50 to 60 gallons down it's really strong. I'm concerned that I could damage the Fuel pump since it's pulling so hard. Ever hear of this before? Thanks

C Nash

Senior Member
Re: Diesel fuel tanks

think this would be normal Jeepguy. Probably part of the emission system work. It pulls the fumes from the tank through the engine instead of venting to the outside air as we used to do. JMO
RE: Diesel fuel tanks

I don't agree with a vacuum being normal - I think I would look at the cap to see if it is the vented type or check to see if the system has a oneway valve that will vent the tank as the fuel is used but not let the fule escape except when excess pressure builds up and it vent the tank.
I have seen the tank supply line leak at a coupled joint this joint is normal about at 1/2 tank and if that joint allows air from the tank to be sucked to the fuel pump however this will cause the engine to starve for fuel and quit.
The vacuum could cause damage to the tank. I would check it out.

Retired Navy
Jackson MS
2007 Tiffin Pheaton 40' DP
2006 Honda CR-V Toad
RE: Diesel fuel tanks

Thanks Jroan, the cap looks to be a non-ventig type. I'll be searching out the ventlines and anything that could be plugged. thanks again for the tips.