fuel sending unit????

[54Caddy]

Was driving truck yesterday and it died. Checked for fuel coming to carb and there was none. So I replaced the fuel pump twice and still not getting fuel. Could the sending unit possibly be bad or cloged? Any one run into this problem? How hard is it to drop the tank I loosend the bed thinking the sending unit would be under it and its under the cab. Thanks brandon
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[SoCalKris]

Ok so first you saw there was no fuel getting to the carb, Did you check for fuel coming out of the Pump. My guess is that your pump was fine. Now for your Fuel sending unit, the sending unit is like the float in your toilet conected to a metal arm. At the bottom of the arm is a sensor, like all sensors they operate off ohms high ohms full tank low ohms low tank. the arm floats up or down. So no it can not be clogged. It can rust or corrode and stop working. But most likely if u tap your tank a few times it will sound hollow try to check if it is empty with a hose if u can. replacing the sending unit is easy enough droping the tank is the hard part. I'm not sure what your driving but most tanks are held up with 2 straps, so disconecting 3 wires, removing 2 bolts and a hose clamp, and the tank falls. good luck, its much cheaper to do the work yourself if u can.

[54Caddy]

no fuel was coming out of pump at all. So that is the reason why i replaced it. The gauge still operates normal and there is still almost 3/4 tank of gas. I understand the way the float operates. But there is also a filter on the end of the pickup tube so i will be taking out sending unit this weekend and hopefully that fixes it.

[SoCalKris]

Now thats an interesting one. Did you go through and check all your inline fuel filters. There is definately a clog somewhere. I believe I have 3 or 4 inline filters on my truck, damn rusty old tanks

[KQQL IT]

There is two short rubber lines under the cab that can crack. Id look there and or the sock and the end of the pick-up tube is plugged.

[bmchevy1979]

Definitely check those short rubber lines I thought my fuel pump had went out and it turned out to be one of those lines had a pinhole

[old Rusty C10]

if your bed is not rusted on like most its prolly easier to remove the bed than to drop the tank

[KQQL IT]

Originally Posted by old Rusty C10

if your bed is not rusted on like most its prolly easier to remove the bed than to drop the tank

pick up is under the cab though.

[justinburnett]

I second the leak check. If it's able to pull air, it won't pull fuel up through the pickup. Like sucking on a straw that has a hole in it, it's easier to suck in more air than lift a column of liquid. The hose is cheap. Chances are if it hasn't been replaced, it could use it anyway.

On the other hand, if you got your fuel pumps at O'Reilly Auto, they're probably bad, and that's your trouble. (had some bad experiences, can you tell?)

[JuicyJ]

Check your fuel selector valve, you got dual tanks. These have been known to go out and not allow any fuel to go to the carb.

[54Caddy]

no duel tanks on my truck man. Also to get to those hoses tank has to come down any way so might as well replacing sending unit while im at it. And no i never get my parts from orielys pepboys or autozone. Either go to gm or napa. Get discount so pay the same as the cheaper stores. The bed is already off took that off yesterday just to find out the sending unit is under the cab could cut a hole in the cab ahhahaha jk now that would be a good one. Well time to get outside and drop tank just got back from work to now get to work again ahaha

[KQQL IT]

8 9/16 bolt and its down. and a ground strap usually

[csb#356]

Have you checked the pump pressure? Is it possible the cam lobe that runs the pump got wiped out?

[54Caddy]

so i droped the tank and nothing in the sending unit seems like it is clogged. Went ahead and ordered a new one. see what happens when it comes in tomorrow. If nothing works then i am leaning toward the cam lobe also but wouldnt that be very hard to do the engine only has about 25,000 miles on it with all new internals?

[csb#356]

Its possible. I think you should test the pressure. Most vacuum gauges work in reverse as a fuel pressure gauge. look for like 5 or 6 psi. I don't know if this is possible but maybe when you installed the pump you didn't get the arm that rides on the cam above it so its just not doing anything.

[bmchevy1979]

You could take a length of hose and connect it to the inlet side of the fuel pump and at the other end have the hose in a container with gas (gas can, small bottle) and if it starts that will let you know it is not the fuel pump

[54Caddy]

Yeah i will do that also today. Damn rain man, soaked the inside of my truck for some reason my window will not roll up got to check that out today too. Will let you guys know what happens they told me the sending unit wouldnt be here till around 3 today.

bmchevy1979- crazy man we live in the same small town and have the same name. Your screen name here has my first and last name initials.

[bmchevy1979]

That is pretty crazy. that sucks about the rain hope it didn't screw up any of your electronics (stereo, etc.)

[54Caddy]

well got sending unit in and nothing changed. So i took off the fuel pump again and it was hitting the rod coming from the cam. While the pump was off in cranked over engine to see if the fuel pump rod would move and it does not. I got it to move barely, tried to take it out and would not come out. So to me it sounds like the cam has messed up which is hard to realize with the eninge only have 20,000 on it with all new internals. I can try and record a video of it tomorrow. Bummer guess it is time for the new 350

[justinburnett]

Did you try it while pushing the rod in towards the engine? It won't move back and forth without pressure on it from the bottom end. Hopefully that makes sense. I don't know if you know how it works so don't take offense.

You can replace the cam without pulling the engine out, and they're not that expensive, if you have to go that route.

By far the cheapest and easiest thing to do, in your case, would be to pick up a low pressure electric fuel pump. You're not looking at more than $50 to get you back on the road. Far better than building a new engine for it (as far as money goes), or you could at least drive it around while you're working on the new engine.

[bmchevy1979]

That is weird I have only seen a fuel pump lobe go bad once and that was on a 200,000+ mile engine in bad need of a rebuild/replacement

[spudz]

If it indeed has wiped the fuel pump lobe.......Pull the push rod, re install pump or block off plate and install a electric pump on the frame rail.

[54Caddy]

Yes i understand how it all works justin. There is no cost involved with the eninge swap, ive had this 350 ready for a while. I can just put an electric pump but out of money at the time. Im going to mess with it a little more today and see what happens. Maybe a bad pump or something. I will keep you guys posted.

[spudz]

my 78 mud truck did the same thing to me, I dropped the tank and all to find nothing wrong. It ended up being the fuel line had a hole in it and was sucking air.

[54Caddy]

yea i replaced all ruber hoses. we will see what happens today.