1989 Suburban 2500 4 WD, after hitting ruts or bumps in the road, there is a 20 amp fuse that breaks each time, upon replacing this fuse the engine will start and run again !!! Any ideas, suggestions or ???

 

Welcome to the forum. When you say the fuse breaks, do you mean blows or actually physically breaks? If it is blowing and it happens when the truck is physically shocked, then there's a circuit that is shorting out. Could be a pinched wire or a wire that's next to hi temp like exhaust manifold that has melted insulation and is shorting out.

 

As best as I can tell from talking to the owner, this looks like a 20 amp ECM blade fuse, that will burn/break when he hits bumps in the road (?) but I am not sure this is happening at every bump.
The fuse block is located inside the cab of the truck up under the dash panel , sort of difficult to access but it is doable.
I am the new owner of the 1989 Suburban at this time, we have a TH400 hydro tranny in it that is giving us some shifting issues, at times will not get into the 3rd gear and sometimes feels like it is slipping in Drive. Thank you for your inquiry ............... Mark