1994 long box I6

When i bought the truck off my grandparents almost a year ago they warned me it sometimes wont start on one of the tanks. So this morning was the sixth or seventh time it's happened since I've been driving it. It wont start on the front tank and happens in the morning (3-12 hours since driving it) but never happens later in the day . The pump will whine but wont start until its put to the back tank.
Most of the time it will start on the front tank and the truck runs good but it's just the odd time. It's not a huge deal but just something that would be nice to get fixed.

Any ideas would be helpful as I can't think of any that would make sense that it would only do it sometimes. ( relay starting to go? )

 

Are you positive it is the front tank only?

 

When it happens the truck will crank to no end but won't start until I switch to the back tank. Never have the problem when I start off with the back tank.

 

Maybe a clogged or collapsed line. I would check to see if the pump is delivering the proper volume of fuel from the front tank. Even though you hear it running it might be clogged up partially. But im no expert

 

Check fuel pressure

 

But why would it start good every other time and still run good?

 

Because the system was able to prime properly that time, other times the pump might not have been able to, I have the identical problem with my rear tank during the summer, It will shutter and die when i try and start it on the rear, but when i start it on the front tank and then switch to the rear it works just fine no problem. You will need to buy/rent/borrow a fuel pressure gauge and test what your tank is putting out.

 

So it will put out the normal pressure when it starts but when it won't start there isn't enough pressure? Is it the pump causing this?

 

Like i said you will have to check the fuel pressure for what its putting out, you can try and start it on the good tank then try and run it on the bad one.