Jump to content

Fuel system questions


Recommended Posts


I am new to this forum. I have an 85 720 with 84k original miles on it. Mechanically the truck is in great shape but I have been having a weird problem where the engine dies when I have a full tank of gas on a downhill slope. I have been thinking its either the fuel filter or the carb. Any thoughts?

Link to comment
  • Replies 7
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

When running properly on the level, move the air filter housing just enough to see the fuel level sight glass. It's a round glass bull's eye with a dot in the center. The fuel level should be near the middle. Possibly your float may be set too high and the carb is over full. Tilting the truck down hill raises the full tank higher and increases the fuel pressure and floods the carb and it stalls.


A fuel filter change is always good to do every year or so, no harm in that, but it won't cause this problem.

Link to comment

According to my Chilton manual, the float chamber is behind the sight glass window. Do I just bend the float so it sits correctly?

You shouldn't have to bend the tab on the float....if...it hasn't been touched before.

Usually there will be crud in the carb filter and or the needle/seat/chamber

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.