Greetings everyone, great site. I filled both my tanks and drove 26 miles on the rear tank and then i was driving to work one morning (10 miles commute city driving) and it stated acting like it was running out of diesel. no power cutting in and out. Thank god when I switched to front tank it worked (new truck wasnt sure switch worked) and it almost immediately started to run fine again.




originally I thought someone syphoned my diesel however when I went to refill it it had only burned the 26 miles worth!!!!!

so what the heck is happening. Ive looked underneath the truck and that cylindrical cannister that sits on the fram rail under the driver has been bypassed and there looks to be a blue aftermarket fuel line tapped in. I see residue at one of the connections. If that is not 100% sealed could it be getting air in it? Should I try the rear again now that its full to see if this only happens after 26 miles? could if be the pickup in the tank? or is that problem related only to sending units? I doubt its the pump because its the same mechanical pump for both tanks right?

keep in mind this is the first time I have ever run through either tank so maybe the rear is contaminated?

any suggestions are appreciated.

 

since you said there was an aftermarket filter in line, it may be possible that if the fuel line was replaced and it wasn't stiff enough, thick enough it may be collapsing and blocking the fuel flow and starving the engine. not sure that's the problem, but would check that as it's a quick check. can't imagine that the sending unit would be running out of fuel in 26 miles as where teh bottom of the sending unit is--not counting the filter screen/tube extension--six inches or more long, so should be getting at least half the tank or more before running dry.
speedrdr

 

Can you post a picture if the............

 

Yeah, that statement has me wondering as well.

 

Could be the Tank switch valve, sometimes they will leak air into the lines. Try bypassing the tank valve and hooking it straight to the back tank, then driving it.

 

I wonder if that could be the problem with mine...

If you start it on the rear tank, it runs for a few minutes and dies...but it seems like if you're driving around and switch to the rear tank, it's fine while you're driving. I dunno.

 

Fuel tank cap?? I had it happen on my 83 but it would only start acting up when I got down to around 1/4 tank.

 

My 87 is doing the same thing almost immediately when I use the front tank. I checked my lines and they look fine. I'm thinking the sending unit has a pin hole in it. I'll eventually drop the tank and fix the dumb thing but for now I'm using the rear tank. I'll post a pic of my fix for the sending unit. I took some steel tubing and bent the end of it into a circle about the same diameter as the old base. I capped the end and used a small drill bit to drill holes in the lower sides of the tube. I think it will work like the original pick-up but not have the same problem of breaking off as I'll connect it using a compression union to connect the two piece.