Recently bought the 3/4 ton work truck and had engine rebuilt. It has a large tank (30 Gall?), but cuts out when gas tank gets to about half full. I replaced the fuel pump in the tank, and thought the problem went away, but it resurfaced again today. Quit in traffic and wouldn't restart, topped up tank with a 6 gall can, and it started right up. Drove to gas station and filled it up: 6+8=14 gallons, which should only be a half tank. Anyone have any ideas why it cuts out as if it runs out of gas when it gets to half a tank? (note that I can hear the pump when I turn the key to start, and before cranking starter, so pump seems to be working)

 

Sounds like the pickup isn't at the bottom where it should be. When you replaced the pump did it look like the sock was all the way to the bottom, or was it bent at an angle?

 

Another thing to try. Throw a can of starting fluid in the truck and when it won't start, spray some in the throttle body and see if it starts. If it doesnt, than you might have a bad pickup asm in the distributor and no spark. This may seem strange but they do get heat sensitive...it's worth a try.

 

Thanks to both of you for your replies. I think I was on the wrong track. Here's what happened: I tried to start truck last night to bring my daughter to a sleepover, and it turned over, sputtered a bit, and quit; tank full. No amount of cranking would get it to turn over (or even sputter again) after this. This morning, I went out and tried again. Crank for 10 seconds, it starts to sputter briefly, then stops and continues cranking. I tried a little spurt of gasoline in the throttle body; no effect. After about twenty tries, it finally caught and coughed to life. Gas, white smoke, and black condensation came out the tailpipe for a while, then it settled down to just running very rich, with wisp of black smoke. Conclusion, seems to be running very rich on a constant basis, and that may be what made it conk out in traffic and not restart. Tailpipe is black.
Question: since this is a throttle body with a new SMEC added at time of rebuild (1000 mi ago), what can be causing it to run rich? I would think it's a stuck choke if it were carburetted, but with TBI, I don't know, may be some obscure sensor(?). Further clues:
1. Tested TBI injectors; they're clean and measuring about 1.3 ohms (manual say's they should be 2 ohms).
2. MAP sensor recently replaced.
3. Ignition is fine (put spark lamp on distributor lead, and spark is consistent). Since it's running rich at idle, hard to get a good read on timing light, but I think timing is OK.
4. Before this week, noticed that truck started fine, then after I got it onto road (after running about 60 seconds) it would act like "the choke closed up" (even though its fuel injected), coughing and smoking, and conking out. I would then crank it for about 10 seconds and it would come to life and run like a watch for the rest of the trip.

Appreciate any help I can get...Thanks
-Dave

 

O2 sensor is always suspect on older vehicles. White smoke is water burning off, black smoke is too much fuel (which I'd expect if you're cranking a lot and not igniting), blue is oil.

Check your spark plugs too. It won't run right if they're fouled or cracked.
hmm. What about the evap system, perhaps there is a problem with it? It's supposed to suck the fumes out of evap after it's warmed up and you're running down the road, iirc.
And I guess check PCV and EGR stuff.

This isn't an easy one to diagnose online. Good luck with it though.