Carter M4845 fuel pump.

[Jerry Hall]

I had a fuel pump go out and didn't have a spare on the shelf. Every big block car I own uses the same pump, unless it's a Hemi. I ordered a couple of Carter pumps from Rock Auto, just using their fitment on the website. I thought nothing about it, because when they arrived they looked the part. It was a usual install until I got to the pump outlet. The metal line that hooks there wasn't even close. It turns out that the outlet is metric and not even close. No one makes an adapter for this that takes a metric fitting and goes to standard 1/2"-20. I then went to a local parts house and they tried to sell me the same damn pump. I told the guy at the counter that there wasn't anything metric on a 440, 383, or any vintage Mopar. Just want to let everyone know not to make that mistake.

 

[68BabyBlue]

I had a similar situation with a pump for my Hemi GTX two years ago. It looked correct, but the fuel outlet was also not right. I got lucky, the owner of the shop that was doing the install and I worked together to cobble up some NAPA parts store fittings to make it work, but there was no way it was happening out of the box.

 

[AR67GTX]

Is there enough meat on the coupling to allow the outlet to be reamed and tapped for the SAE fitting. Or is the metric hole already bigger than the SAE fuel line fitting.

 

[pnora]

That should be 1/8 NPSF IN thread size

 

[Jerry Hall]

Is there enough meat on the coupling to allow the outlet to be reamed and tapped for the SAE fitting. Or is the metric hole already bigger than the SAE fuel line fitting.

It's much smaller. That would probably be a solution, but unless you can do it yourself, it would not be a economical solution. I have never had a problem getting a correct pump before. It just seems ironic that they would make something for an American car 50 plus years old with a metric fitting. I could have also got a metric nipple and hooked it up with a rubber hose, but on a correctly restored car, I'm just not going to do that.

 

[pnora]

It's much smaller. That would probably be a solution, but unless you can do it yourself, it would not be a economical solution. I have never had a problem getting a correct pump before. It just seems ironic that they would make something for an American car 50 plus years old with a metric fitting. I could have also got a metric nipple and hooked it up with a rubber hose, but on a correctly restored car, I'm just not going to do that.

Are you sure its metric. The specs for that pump suggest the size I posted above.

 

[Jerry Hall]

Are you sure its metric. The specs for that pump suggest the size I posted above.

I went to the local hardware store and found a metric fitting that screwed into it. I'm not sure what the actual size was, but it couldn't be converted to fit my other line.

 

[Jerry Hall]

CARTER M4845 Specifications
Outlet Quantity	1
Outlet Fitting Thread Size	1/8" - 27 NPSF
Inlet Type	Hose connection
Fuel Pump Type	Mechanical
Outlet Type	Threaded
Gasket or Seal Included	Yes
Minimum Flow Rating	33 GP
Inlet Fitting Thread Size	3/8 in
Minimum Pressure	8.0 psi

This is their posted specifications, which I didn't look at when ordering. I took their lookup tool to be correct. Either way it's not the stock outlet size on my cars.

 

[pnora]

CARTER M4845 Specifications
Outlet Quantity	1
Outlet Fitting Thread Size	1/8" - 27 NPSF
Inlet Type	Hose connection
Fuel Pump Type	Mechanical
Outlet Type	Threaded
Gasket or Seal Included	Yes
Minimum Flow Rating	33 GP
Inlet Fitting Thread Size	3/8 in
Minimum Pressure	8.0 psi

This is their posted specifications, which I didn't look at when ordering. I took their lookup tool to be correct. Either way it's not the stock outlet size on my cars.

You would need a brass adapter with that thread size on the pump end and 5/16 female inverted flare on the other for the flared line end. the 5/16 inverted thread is 1/2 20 tpi

 

[pnora]

Its stupid the way they change things. The 1/8" - 27 NPSF is basically a 1/8 npt. The f suffix is for fuel and there is a minute pitch change supposedly so the fittings seal without sealant. I use a film of paste and a 1/8 npt will go in there.

 

[Jerry Hall]

You would need a brass adapter with that thread size on the pump end and 5/16 female inverted flare on the other for the flared line end. the 5/16 inverted thread is 1/2 20 tpi

The pumps I have previously purchased had the 1/2 20 tpi outlet. I think I have located some that are correct made by Airtex.

 

[pnora]

Fuel Pump Fitting for Carter M4845 pump outlet | Roseville Moparts

 

[moparedtn]

Always wondered about the "hemi" fuel pumps:

These things have 1/4" in and out, yet they're rated 120gph.
How the heck is that possible?
Anyways, I digress...

Jerry, I'm wondering if the M4434 isn't the one you're after? Supposed to have a 1/2"
outlet?

 

[pnora]

Here is an old Moparts posting on the same issue. Carter M4845 Fuel Pump Outlet Issue.....

 

[Jerry Hall]

Always wondered about the "hemi" fuel pumps:
View attachment 1484003
These things have 1/4" in and out, yet they're rated 120gph.
How the heck is that possible?
Anyways, I digress...

Jerry, I'm wondering if the M4434 isn't the one you're after? Supposed to have a 1/2"
outlet?

I agree Ed. Looking at those Carter pumps with the 3/8 inlet and that little bitty outlet made me think the same thing.

 

[Jerry Hall]

Thanks @pnora for all the information and the availability of that fitting.

 

[pnora]

This can work and the Airtex might be made to copy it. The outlet is clocked slightly different but should be 5/16 inverted flare. Carter Mechanical Fuel Pump P/N:M6774 724956018444 | eBay

 

[moparedtn]

I agree Ed. Looking at those Carter pumps with the 3/8 inlet and that little bitty outlet made me think the same thing.

Did you take a look at that Carter M4434 I mentioned?

 

[Jerry Hall]

Did you take a look at that Carter M4434 I mentioned?

Yes, it may work, but may still need some kind of adapter for the flared line connection. If the pump I'm looking at doesn't work, I will get some of those adapters as in @pnora post.

 

[moparedtn]

Here is an old Moparts posting on the same issue. Carter M4845 Fuel Pump Outlet Issue.....

I just went out to the garage and pulled the similar pump I have as backup (came on the engine)
that is the same as that Carter and yep, it has that funky adapter fitting shown in that Moparts thread.
Interesting that one poster says that type of pump runs a little high on pressure, though?

He recommends the same M6903 "hemi" style pump as the one I pictured above because it supposedly
runs a lower pressure, but delivers the flow?