With a cup of fuel poured into the carb bowl and engine running, you could measure the vacuum the pump creates on the inlet side.
If vacuum is registered, then you may need to replace the rubber hose sections at the tank, two of them, one at the sending unit to hard line and the other section right behind the pass rear tire on the frame rail.
After replacing those two sections, you may need to prime the line to the pump inlet by disconnecting the inlet hose to fuel pump and inject very low pressure air into the fill tube and use a rag to adapt the blowgun to filler tube. Once fuel comes out inlet hose, reconnect to pump.

No pump vacuum, pump diaphram broken or fuel pump rod missing or not on fuel arm, but then pump would not bolt up the block.

 

Everything from the sending unit (but not including) to the carburetor is brand new. The lines and rubber lines and all brand new.

Please tell me you djdn't forget to remove the bolt that holds the fuel pump push rod while you replaced the pump. That can cause nasty problems.

Can you explain this further? I did some research and just NOW found out that theres a push rod that activates the pump, I didn't notice anything while changing the pump. Is it possible its missing?

If it was missing, would I be able to get to the pushrod by taking off the passenger side valve cover?

 

Please tell me you djdn't forget to remove the bolt that holds the fuel pump push rod while you replaced the pump. That can cause nasty problems.

 

Pop the pump off and if the pushrod is there you can see it or at least stick your finger in there and feel it if it's hung in the block. It's not typical for it to hang in the block when you pull the pump out but it could happen. It has to be pushed back when the pump is installed so that you can get the pump lever in. If you need one, you just remove the two smaller bolts on the pump plate on the block once the pump is removed and insert it.

It's not uncommon to have to prime the pump if you changed out everything. It can take awhile for the pump to pull fuel through a fresh install. I've just removed the line from the carb and sucked it to prime the pump on occasion. Do so at your own risk.

 

I've just removed the line from the carb and sucked it to prime the pump on occasion.

Eeew

 

I ran a rubber hose from a bottle of gas to the pump to the carb and the line was still bone dry.

Assuming u have the pump rod in....a dry diapham pump like most fuel pumps are not self priming...often they have enough suck to get a little fuel to them, once 'wet' pump nice.
BUT if there is the slightlest air leak in the fuel lines before the pump it will stop pumping.
A quick way to get fuel to the pump is a vaccuum cleaner on blow in the fuel tank..or low air pressure.
Not uncommon on older cars when they used to run out of gas.

 

Sounds like you are missing the fuel pump. There is a extra lobe on the cam that this rod operates off of, and it pushes the lever on your fuel pump. As stated, take the pump off and feel/look up in there. If it's not there, time to get one.

 

Check this link out: http://67-72chevytrucks.com/vboard/showthread.php?t=138417
Nice tutorial.

This pic shows the fuel pump pushrod hanging out. It won't look like that normally.

 

When I've had problems priming a fuel pump its been resolved by putting an air gun wrapped with a shop rag in the fuel tank filler hole to create a little pressure to move the gas to the pump. You can do this while having someone crank the engine or remove the inlet line at the pump until you have some coming out. You don't need much pressure at all, and you won't create much pressure in the tank because the towel won't seal perfectly.

 

Whats the history on this car and its fuel issues? Did it run before with the previous pump? I would think that you would notice that there was nothing for the pump arm to contact if the rod was not there when you installed it. You should pull the pump and make sure the rod is in place. As far as holding the rod in place while the pump is out I have used grease on the rod before, just enough to hold it up there. Also prime the pump by adding a little fuel down either side like mentioned before.

BTW Joe this is a family site, please don't post pics of your pump rod hanging out like that...

 

No real history that I know of. The car was started without the pump (the guy I bought it from dumped fuel straight into the carb), and it ran fine. The first few times I started the car, there was fuel in the lines (all brand new lines, so it was new fuel) and the pump just... stopped working. Weird, but I assumed possible.

 

Oh crap!
Thanks for catching that man! I'm so used to going commando, I forgot where I was.

 

I think it might have been the pushrod.

I installed it like this...

How can I reset the pushrod to install the pump properly?

 

The rod just floats in there. I use a small flat piece of wood, like from a wire brush handle. It's thin and wide enough to hold the rod up while you insert the pump.
You could use a small flat-blade screw driver or a thin ruler.

You're good, you just forgot to push the rod all the way in before you put the pump arm in. Put a dab of grease on the end of the rod or tip of the arm. Push the rod up inside and hold it there while you insert the pump arm. You might be able to see the rod fall back out and make contact with the pump arm. Then yer good!

 

As Joe says above, a bloody good dollup of grease
this method is great for holding screws on screw drives, inside sockets and sticking notes to a wall...and works better than hair cream lol

And a quick test of a pump, out of the car...pour a little petrol , kero, what ever in to the pump...bloke off the inlet and out lets with your fingers and pump it.
you will feel the suck and pressure.....but as I mentioned above, diapham (and gear) pumps need to be primes to work......

 

Oh my God. I pulled the pushrod out because I couldn't move it. It's bent, and not just a little. It's a massive bend.

Here's where it bent.

What could have possibly caused this? This is one thick pushrod...

 

Looks like as I said someone left the bolt in. On the front facce of the block there are two screw holes. one shoul have a short capscrew in it to keep oil from leaking. It lines up with the pushrod. You can put a longer bolt in to contact the push rod to hold it up while you install the pump. DONT FORGET TO CHANGE IT BACK TO THE CAP SCREW or you could bend the rod or wipe out the ecccentric lobe on the front of the camshaft. Grease is better. At least you found the problem IF the eccentric is not wiped out. Then your options are change the cam or install an electric fuel pump.

 

Yeah, the pump really didn't come with instructions, so I pulled the old one off and sat the new one in there, I didn't see the pushrod, but I guess I didn't think about it at the time.

I'll check for the capscrew tomorrow, when I install the new pushrod.

 

I would think after pulling a bent pump rod as shown, the bore in the block probably ain't straight anymore. Adding a new pump rod and it will be bent in its future.

I suugest adding a block-off plate to where the fuel pump bolted onto and add an electric fuel pump back by the tank as external pumps push better than they suck.

 

Yeah, I'm not 100% if it's straight, but the rod didn't move, it was stuck in place (by my pump installation), so I'm fairly (but not 100%) sure it didn't move back into the block or toward the cam.

Aren't electric pumps fairly noisy? Could I get an EFI-like intank unit, and just block off what I don't need, if it came to me needing one?

 

After seeing the bend in the push rod, it might be a good idea to check the lever on the fuel pump to make sure it wasn't damaged. I've never known a fuel pump to be bolted in place if the fuel rod is not raised high enough to clear the fuel pump lever.

 

The pump still looks OE.

 

I'd just get a new pump rod. They're cheap. Then stick it up in the block and wiggle it to check the bore. Your first pic shows the pump all the way out against the plate and you said you couldn't get it to move back, so that would seem to say it was never against the cam. You were also able to get the new pump on without and issue.

The previous owner might've tried to get the pump on without pushing the rod back and bent it with the pump arm. I reckon if your pump bolts are long enough you can get the pump leaned downward so they'll start and then tighten them up to pull the pump to the block and force the lever down into the rod. Never ever seen it done but that doesn't mean it couldn't happen. I've seen a SBC head removed without pulling the lower row of bolts that are outside the valve covers so never underestimate brute strength and stupidity.

 

I've seen a SBC head removed without pulling the lower row of bolts that are outside the valve covers so never underestimate brute strength and stupidity.

I don't mean to hijack this thread but I gotta see pics of this.l
Ya got any?

 

By the way that rod is tore up I would guess the bolt was in place. For now I would replace the rod and check the oil for metal. If it did waste the pump lobe on the cam then it would probably not pump or pump less anyway. Might put you in a lean situation if it can't keep up. Hopefully you can get away with just the rod.

 

It's bent, and not just a little. It's a massive bend.

Yep thats what we call here "sucked a kumura"

9 times out of ten a new rod goes in and works fine....when it doesnt, the casing is usually cracked.
Give it a go m8 as suggested above...if the new one slides smooth....may even have to look inside and take a couple dags off with a needle file.

 

It slide in fine. I haven't bolted it up yet, but test fitting there was no wiggle (just enough to move up and down), so I'm guessing it didn't break/crack/destroy anything. I'll find out here shortly when I bolt it all up.

 

Installed. There was no capscrew (atleast, I couldn't find one, I did see the two front holes, nothing in them).

Nothing happened, I poured gas down the carb line and cranked it over, I didn't get anything. I tried for a few minutes. I had to leave, so I didn't get a chance to take it back apart to see if the push rod bent again.

 

...sounds like you got a bit lucky, prob be fine then.
This stuff happens....that pushrod can be a little fiddly when putting a new pump on and lined up with the pump lever and all bolted up.

 

So just keep working with it for a while and it should start up?

Because I'm close to throwing in the towel and getting one of those "quiet" electric pumps.

 

Any new mechanical fuel pump I have ever installed self-primed within 1 minute of cranking and provided fuel. As the engine turns over pump the throttle a couple times every 5 seconds or so. If this doesn't get you gas then....
This might seem a little hairy but it's really not. I've checked before like this. Take the pump off, hold the rod up against the cam with a finger tip and have someone turn the engine over a few times. The rod should pump in and out. If it doesn't then the cam doesn't have an eccentric or the eccentric got ground down. If the rod pumps in and out then pour a couple teaspoons of gas down the carb to get the engine to start and repeat as necessary. You're taking steps here-make sure the rod pumps, then get fuel.

 

hmm....sounds like it may've wasted the cam lobe.

If you're sure it's not pumping fuel and you've tried the priming trick, I'd suggest removing the pump and turn the engine over by hand...and have another person hold the pushrod snug to see if it's moving.....

 

Don't give up just yet, try a couple of teaspoons of gas down through the carb butterflies to get the engine to run for a sec or two. Maybe just enough to pull and prime the pump. Other wise, as mentioned before, see if the pushrod goes in/out when cranking, like Moonpie and Garfield said.

 

I had an issue because of the dreaded E10 fuel evaporating and the carb floats stuck ckosed not allowing the carb to fill. Loosen the fitting at the carb or on the pump discharge to see if there is flow. You can completely fill the carb with a small squirt bottle thtough the vent tubes. Should run for a couple of minutes, plenty of time for the pump to pick up if thee is no other problem. No sparks.