85 300 SD: fuel tank sender erratic

the gas gauge is going from correct reading to full off intermittently, and the lower the level in the tank, the worse it gets. Banging the instrument
cluster does nothing, so I am thinking it is the sender. I don't know where to look on the tank for it so I can see if a connection is loose.....where is it located? Also I wanted to try adding some gasoline into the diesel fuel to see if that would clean the sender. When I fill up, how much gas can I mix in without causing harm to the engine? Is it one gallon gas to a tankful? thanks!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The sender is accessed from the top of the fuel tank - behind the panel in the front of the trunk.
Suggest you first consider an algaecide or other fuel system cleaner, especially if the car isn't being regularly driven. 100% Biodiesel cleans out the fuel system - into the filters.
Of course the sending unit may just be worn out.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Don't put gas in a deisel.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Don't use gas if you want to keep your engine. You can use kerosene, but it's safer to use the fuel additives you can find in the local Mega-Low stores. They have the algaecide that will clear up the green goop that grows in diesel fuel and makes your fuel gauge lie to you. Instead of using the recommended rate (32 oz per 100 gal), put the full quart into your next fill-up. Do that for the next three or four tanks. I keep a bottle in the trunk all the time. When I fill up, I pour in about 8 oz. Keeps the problem under control, most of the time.
Of course, the sending unit may just be worn out.
Larry In the back yard, under the oak.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Is it the same reason for the same problem on a petrol powered model and does the solution for the diesel powered model also apply? Mort

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.