So, I read the post on here about swapping the fuel pump (amazing write up) and for about 20 miles my problems were gone.

I've recently replaced the following:

Radiator
Fan clutch
Water pump
Thermostat
Fuel pump
Starter
Fuel filter

So when I fill up, top it off to the brim, I drive away fat dumb and happy. Once it gets to half a tank it dies. I have to add fuel to get it to start. So my 20 gal tank goes down to 10 gal, and if shuts off. Obviously it's got gas, and a pump to deliver it... Is there some sort of kill switch on the pump when the sending hint reads empty the pump stops pumping? Is that what this is? The sending unit is bad, doesn't read normal. It reads full down to just under half, then all the problems start. (Hell I'm not even sure it's bad... But it didn't look great when I had the pump out).

So I have the same symptoms other people have, yet I have new parts... What could be going on here? Something is telling my pump not to send fuel. I only know this because once it dies (at half a tank) if I try to turn it back on I haven't heard the fuel pump like I normally can.


Anyone care to chime in?

 

when you fill it up to the brim, drive until it dies, and then fill again, how many gallons are you adding? I wonder if your sending unit float has a hole in it and the float is filled with fuel, making it sink down giving a false reading?

 

Right at 10-10.2 gals and it's doing this non sense.

Would it be ok to just take the sending unit out, run the vehicle that way?

Also, I checked the float when the unit was out, it's in new condition. There's no corrosion, no holes, just shiny black plastic.

 

I had a somewhat similar issue about 10 years ago. The gauge would read half a tank and suddenly drop off to empty. I believe I replaced the sending unit and float and all was right again.

 

I should add though, my tank actually was empty. Not sure why yours would only be emptying half way and then shutting off. I would be very interested to know what the solution is when you figure it out.

 

Can I just run it with no sending unit, or will things not work right without it?

 

the sending unit and pickup tube are one in the same and installed on the pump assembly. You can't remove it and run without it. It may be that the pickup location on the pump is bad, has a hole, etc. Unfortunately more diagnostic work will be required to figure out the exact issue.

 

10-4.

I spoke with a mechanic who thinks it may be the crank shaft position sensor. Ideas?

 

The CPS could very well need to be replaced, and is easy enough to do yourself.

 

Does it happens every time you hit half a tank? If so, I would say it is not the cps. It may be a bad pick up tube like someone else mentioned.

 

yeah, if its consistently at half a tank (not just half way on the gauge), then I'd suspect that your pickup tube is broken or rusted part way down. If they rust, they can get a pin hole at a certain point, and then lose suction and the pump basically pushes air.

 

Where is the pick up tube at?

All new hoses went onto the pump, but if y'all are saying "rusted" this can't be it because all the tubes I replaced were rubber.

So where can I find the pick up tube?

 

the pickup tube is part of the pump / sending unit inside the tank

 

All the tubes I had were rubber... It's a metal "tube" for one inch on the outside of the cap, one inch on the inside. Then it's rubber in each direction.

 

I still have some gas left to burn before half a tank. I'll pull it, check everything on my work bench and check for pin holes, also gonna check the inside of the tank, see what's going on there.

Crossing my fingers