Fuel pump not pumping fuel through line?

[Lordofthepings777]

Recently got a 73 Newport, and I’ve been doing passive work on it.

Changed the fuel pump a little bit ago (let’s not speak about how annoying it was to install), and now it’s time to start up. I tried the main fuel line, but it wasn’t putting any fuel into the carb.

So- I took the line off before the pump, and stuck a hose into a can. STILL I’m getting the same result. When I crank, the line into the carb puts out air pressure, but no fuel. Tested this by putting my finger over the hard line and feeling for pressure. Is this normal? Is there a clog? Any ideas of what could be wrong?

Any advice from someone who has installed these mechanical fuel pumps?

That’s all, thanks.

 

[Big_John]

I will bet your problem is the tank pickup. It's either clogged or the hose connecting the tank to the line has a hole in it.

And not to be a wise ***, although that's a title I've had since I was a kid, are you sure there's gas in the tank? Don't depend on the gas gauge since this is a new car for you and it's not unusual to have a problem with the gauge and/or sender.

 

[413]

It's pumping air so it's working. Take your supply hose out of the can and hold it up and put some gas in the hose so it will get the pump wet. Now crank the engine with the line held up, sometimes that helps them start working.

 

[Sixpactogo]

If it has been sitting quite a while, I agree with Big John. Probably a plugged sock in the tank. Not sure I understand your comment about the hose in a can. Are you saying you hooked a hose from the fuel pump to a can of gas and still got nothing to the pump? How long did you crank the engine? As for the tank, try, blowing some compressed air thru the line from the pump connection back to the tank. Have someone remove the gas cap and listen for any air getting through. I'm betting you will be pulling the send unit out. Maybe dropping the tank to clean out the rusty gunk. If that is the case, you should put on a new sock and while you have the sender out, verify the accuracy of your gauge.

 

[Lordofthepings777]

If it has been sitting quite a while, I agree with Big John. Probably a plugged sock in the tank. Not sure I understand your comment about the hose in a can. Are you saying you hooked a hose from the fuel pump to a can of gas and still got nothing to the pump? How long did you crank the engine? As for the tank, try, blowing some compressed air thru the line from the pump connection back to the tank. Have someone remove the gas cap and listen for any air getting through. I'm betting you will be pulling the send unit out. Maybe dropping the tank to clean out the rusty gunk. If that is the case, you should put on a new sock and while you have the sender out, verify the accuracy of your gauge.

Yes, I ran a second test with the “IN” hose of the pump to an external can with gas in it, and it still pumped nothing but air. Someone else suggested it could be that I need to wet the pump by physically pouring gas down the hose.

As for dropping the tank and using air pressure to clear the lines yes that sounds reasonable and if I can’t get it running off an external can I’ll try to clear all lines and tidy up the fuel system all together (replace sending unit if necessary and clean tank out while it’s dropped).

 

[Lordofthepings777]

It's pumping air so it's working. Take your supply hose out of the can and hold it up and put some gas in the hose so it will get the pump wet. Now crank the engine with the line held up, sometimes that helps them start working.

Glad to hear it’s probably working. I’ll give this trick a try tomorrow. I wasn’t sure if there were small things like this that could help it for its first time pumping (since it’s a brand new pump), but we will see.

If it doesn’t help I’ll see if the lines are clogged and possibly drop the tank on the car all together (eventually). Thank you

 

[CBODY67]

If you notice, the elevation of the fuel pump inlet line is below the level of the fuel tank. This can promote a bit of gravity feed to the pump.

As to the sending unit, the only part of it that relates to fuel flow is the intake pipe (which had the basic "moisture" filter on it, rather than a normal fuel filter like is near the pump outlet). So no need to replace the sender with a new one due to fuel flow. Most of the new senders (unless OEM Chrysler) do not typically read like the OEM one did, from what MANY have noted over the years.

Replace ALL of the rubber fuel line sections. One at the tank itself (with the special grounding clamp!), one at the rear of the front stub frame, and the sections related to the inline fuel filter. If the one at the tank is leaking/seeping, that can ruin fuel delivery from the tank, as that is usually the highest part of the fuel line route.

As to "running the engine from a can", a better way would be to use an outboard motor boat gas tank. Some come with priming bulbs. Big-box sporting goods stores should have them.

Please keep us posted on your findings,
CBODY56

 

[1970FuryConv]

Glad to hear it’s probably working. I’ll give this trick a try tomorrow. I wasn’t sure if there were small things like this that could help it for its first time pumping (since it’s a brand new pump), but we will see.

If it doesn’t help I’ll see if the lines are clogged and possibly drop the tank on the car all together (eventually). Thank you

What happened?
You can test the new fuel pump with a vacuum gauge. Should draw minimum 10 inches of vacuum at 500 rpm, fuel pump dry, with someone cranking the starter over. If not you either have a bad fuel pump or a bad fuel pump pushrod.
When you installed the fuel pump, did you check the fuel pump pushrod length?
In April, I had an OEM fuel pump pushrod grind down. ***** to get out, because of metal ridging on ground end. Caused hard starting, 7 inches of vacuum only. Couldn't push fuel past the fuel filter. Cam lobe OK, fortunately fuel pump pushrods are made softer than cam lobes.
But look at the difference:
Ground end at left.

Here's a good OEM pushrod. 3.220" is correct length

Hope you fixed it, whatever the problem!

 

[65Port]

Had this issue on an M body and the solution was to pull a gentle vacuum on the fuel line with a hand operated vac canister until fuel came up. Fuel lines were all checked, it just needed some help. Started right up every time after that.

What did you end up finding out?