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Discussion Starter · #1 · (Edited)
Hey guys. I'm working on a TBI 350, and I'm getting no fuel coming out of the injectors. The motor will fire and "run" on starting fluid so the ignition system seems to be fine.

From what I remember, there's only so many components to check here. The fuel pump relay was removed and tested fine, and the fuse was good as well. I did have a little mouse nest up in that compartment, but I have cleaned that all out and see no wires damaged.

My last hope to keep from dropping the tank is checking voltage back at the wiring harness to the tank. I'd prefer not to drop the tank as this $50 job will more than likely turn into $250+ if I have to replace the entire sending unit. The lines up top have seen better days and I'm 99% sure they won't survive me dropping the tank.

Any thoughts? Perhaps something I have overlooked?
 

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Commissioner Gordon
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There is a connector to the fuel pump on top of the frame near where the fuel filler neck runs. Pull that connection and check for + and -, if all is good there, then it's 99% likely it's the pump. There is a ground in that same area, make sure it's attached (some people cut it when doing a fuel pump and never reattach it), it could make some things go nutty.
 

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put a funnel in the filler neck and listen to see if you can hear the pump. a bad module in the distributor can cause no injector pulse therefore no fuel to go in the engine.
 

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Use a test light between the injector connector pins and check for pulsing light. One side is ign power and ECM grounds the other. No pulse can be a module or ECM, or just possibly a blown ECM fuse(or not hooking up the test light right), if there's a pulse then there's no fuel pressure
 

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I agree with all above, you most likely need complete fuel sender and possibly wire harness repair for corrosion. It may also be easier to remove the bolts from the box except the last two in the rear which you can just loosen and lift the bed up for access to the tank.
 

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Most likely a bad sender. Mine went right after I filled my 40 gallon tank on my burb. Had it up on a trailer so I left it, It sure gave me lots of room underneath.
 

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Do you hear the fuel pump run when you hit the key? If not when you first turn it to run, bump the starter once and then listen. You should hear some whine. If the pump runs, you have other places to start probing for voltage than all the way in the back. Chances are it's the pump - I've had to replace one on each Tahoe Vortec 5.7 I've had. You'd think GM could make a better pump. GRR..
 

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Make sure that you buy a new OEM pump if it is cause the aftermarket ones are worse at going out!
 

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I'd almost bet it's the pump. Before I retired, I must have replaced dozens of them. Also, when you have the tank down check for loose baffles. The spot welds commonly let go and the baffle swims around knocking the sock off the pump or the wires. First time I had one it took me 3 pumps before I figured out what was knocking them out. Got a new tank from a dealer. The parts guy said, " oh yeah, that happens all the time, the spot welds don't hang on with all the galvanizing." Unless it's a plastic tank. Then check the grounds too.
 

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if you take your palm of your hand and hit the bottom center of tank, or lightly hit it with a rubber mallet......sometimes it will jar the pump, and get it going again. Been there done that....
 

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Discussion Starter · #12 ·
It's the pump, sorry guys...forgot I had asked about this. Repair became less of a priority due to it getting really cold out lol. I've got voltage all the way back and no pump whir even after slapping the tank with a wood block / hammer.

Thanks for all the help!

Now the debate is on...cut a hole in the bed (and spot weld back in place of course) or drop the tank...hmm...
 

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Commissioner Gordon
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Pull bed or tilt the bed.
 

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is the pump pumping the right way. i had 87 350tbi in my gmc, it had 2 tanks and one would not work but i could hear the pump run and it was pumping the wrong way.
 

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I would just drop the tank, or raise the bed. I would not cut a hole in it. The bed should have 6 bolts or so, and they are pretty light. A couple of guys can tilt it up and put some braces to keep it up and go from there. Good Luck.
 
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