New mechanical fuel pump not working

[Wietse]

Hey all,

Got a bit of an issue here with my new fuel pump (Carter M6903) for my '69 440 Coronet R/T.
There is plenty fuel coming from the supply line, once i release the suction hose it is pouring out.
Using a vacuum pump and pull the fuel through the pump and filter also shows plenty fuel coming through.
When cranking the engine with the pump discharge hose disconnected and put in a bucket there is no fuel coming at all.
Checked the push rod in the engine which slides nice and easy and made sure the pump lever sits in front of it. (guess that if that is not the case it will not go in anyway)
The pump lever has a small stroke of "easy" movement which is against the spring that can be seen, after it gets very hard but returns to it's original position. (Compared with my old pump it feels the same)

What could be the issue here?
Being able to suck fuel through shows there is no blockages, has to be the pump imo.
Just to confirm, there should be nothing in between the pump push rod and the operating lever right?
Nothing that could fall out and end up in the sump?

 

[493 Mike]

Did you check the action of the pushrod while rotating the engine? Lobe on cam could be worn.
Mike

 

[eric383]

Did you measure the length of the pushrod? It should be 3.22". Good luck.

 

[Wietse]

It's the same model pump as the old one, so same size etc.
How can you check the push rod is being operated?

 

[moparedtn]

Did you measure the length of the pushrod? It should be 3.22". Good luck.

Seconded. As I've discovered the hard way, not all fuel pump pushrods are created the same anymore and they are a point of high wear, sometimes quickly, because of some of their inferior hardness versus the cam metallurgy.
Mancini is one that sells a special "extra tough" pushrod for just this reason.

 

[Mike67]

I'm confused, is the pump pulling the fuel or did you use a vacuum pump?
Like others have said could be a bad rod but if it's not doing anything I suspect a torn diaphragm...

 

[Wietse]

The pump is not displacing anything.
I was able to suck fuel through the pump and filter with a vacuum pump and there is loads of fuel passing through.

How is it possible a new pump would have a torn diaphragm or incorrect lever??

There is not other part between the push rod (round bar from camshaft) and the pump lever is there?
Nothing could have fall down in the sump right?

 

[Pops1967GTX]

There's a threaded plug in the block right under where the mechanical fuel pump goes. Take a look while cranking engine over to watch pump action.

 

[747mopar]

I'm thinking it's the pump, could be a diaphram or a stuck valve. There should be an inlet and outlet check valve, either one sticks and it won't work. I've only had 1 Carter and it didn't last a summer, could be a fluke or they may be going downhill.

 

[Pops1967GTX]

 

[mikeyfrano]

Sounds like your push rod is worn. Change your oil quick and clean out your oil pan. The pushrod is designed to wear before the cam gets messed up. I had a 1/2" worn off of mine and it wouldn't pump any fuel.
Good luck

 

[Wietse]

Well, the old pump came off working (might be on low pressure, who knows) but the new one is exactly the same.
Same type/size lever etc. so if the push rod or camshaft is worn the other one also should not have worked.
I suspected fuel startvation at high load as it does go down at high revs and recovers when i slow down, main reason for replacing the fuel pump in the first place.

Can someone please confirm there is nothing else supposed to go between the push rod and the operating lever of the pump, something that could have fell off without me seeing it??

 

[Mike67]

The pump is not displacing anything.
I was able to suck fuel through the pump and filter with a vacuum pump and there is loads of fuel passing through.

How is it possible a new pump would have a torn diaphragm or incorrect lever??

There is not other part between the push rod (round bar from camshaft) and the pump lever is there?
Nothing could have fall down in the sump right?

So everything you've ever bought worked perfectly out of the box???
It could have been a mfg flaw, or torn during assembly...
I had several pieces that were DOA...thats the only thing that has changed (pump). The old one worked just not very well at wot, right? That could be from old age or a worn shaft... but it still worked...The new doesn't work at all...process of elimination leads me to believe it's the pump...even if the shaft is worn it should work a little better than the old. The length only affects the length of the stroke on the pump...it will still pump just not the volume as a full stroke, kinda like a bicycle pump...you can short stroke it and it will work, just not as efficient as a full stroke...

 

[moparnation74]

So everything you've ever bought worked perfectly out of the box???
It could have been a mfg flaw, or torn during assembly...
I had several pieces that were DOA...thats the only thing that has changed (pump). The old one worked just not very well at wot, right? That could be from old age or a worn shaft... but it still worked...The new doesn't work at all...process of elimination leads me to believe it's the pump...even if the shaft is worn it should work a little better than the old. The length only affects the length of the stroke on the pump...it will still pump just not the volume as a full stroke, kinda like a bicycle pump...you can short stroke it and it will work, just not as efficient as a full stroke...

The pump is the problem, period....

 

[Wietse]

I had the pump open and all looks ok, no damage etc.
Checked the rubbers in the check valves but all in place?

To measure the push rod length you have to get it out but this includes removing the front cover etc. correct?

I will build back the old pump and try again...

 

[Pops1967GTX]

How to you know low fuel pressure? Did you place a pressure gauge for a measurement.

Do a process..Simple operation. Fuel pump lever is in contacts the fuel pump push rod which is contacted by the cam lobe..
to have proper contact the push riod must be 3.25 in length & the cam lobe
Wear should be minimum. To operate correctly.

http://www.heritech.org/cuda/fueldelv.html

 

[moparnation74]

I had the pump open and all looks ok, no damage etc.
Checked the rubbers in the check valves but all in place?

To measure the push rod length you have to get it out but this includes removing the front cover etc. correct?

I will build back the old pump and try again...

Remove the pump and below that is a pipe plug, remove that and drop the rod...

 

[moparnation74]

That pump may not have sealed around the perimeter(loose bolts) and could have been sucking air....causing a pumping issue...

 

[dieseldazzle]

Hold the end of the pushrod with your finger and turn the engine over by hand it should follow the lobe on the cam.....

 

[Ranger16]

The pump is not displacing anything.
I was able to suck fuel through the pump and filter with a vacuum pump and there is loads of fuel passing through.

How is it possible a new pump would have a torn diaphragm or incorrect lever??

Made in China?