fuel pump question

Are the fuel pumps for all AMC V8 engines the same?

 

There's something different from early to late (different PN), but they are all compatible AFAIK.

 

there are 2 versions.

on one the connections point up, on the other one they point down. They are interchangeable as far as the engine is concerned, if you can connect the fuel lines you're good to go.

 

I guess if you have a smog pump the fuel pump goes down and the opposite if there is no smog pump?

 

No, it's year related as I recall. Look at RockAuto.com and you'll see a break in the part numbers in the late '70s. Smog pump should have been present throughout that whole range, and in the same location.

 

The top fuel pump is the 1976 and I think it goes up.... the bottom pump is from the 1975, and my pump goes down. I can't imagine that the AMC V8 motors were any different from a 75 to 76 that would cause them to redesign the fuel pump and gear. So the question is.... are these interchangeable by just flipping the direction of the pump? Does anyone run the top pump and does it go up or down?

 

The Carter pictures are a little better:

Early:

Late:

Now, the bolt pattern looks inverted between the two - unless the late model mounts with the connections pointing up. Certainly the style of lever is very different between the two, and that may be because one lever rides on top of the eccentric (newer style) and the other rides under the eccentric.

 

Thanks Timgr for your help on this..... I sent an email to the owner Randy Guynn (owner of American Performance) and got this detailed answer. Thanks Randy.

Sean,

ALL AMC Mechanical fuel pumps for all V8s will interchange. However all are not equal. Here is a few things to consider. Some mount with the fuel reservoir pointed up, some pointed down. These are the common "pressed" together type of units. These type units have a limited capacity. The best Mechanical pump made comes from CARTER, and these are bolt together units that flow high volumes of fuel. These come in Cast aluminum or Polished aluminum and the price has shot up dramatically over the last 2 years. Then there is a Race Type 6 diaphram mechanical unit made by Rom McMaclkin that is fairly expensive but it will flow enough fuel to feed a Nascar quality engine.

I would opt for the Carter High volume unit. Here is why. Back in 74 I bought a brand new AMX, 360 automatic. From a rolling start getting on the freeway, you could stomp it, the car would buzz right up to 70-75 MPH, then start bucking & snorting . Let up on the throttle and hold it at a steady 60-65, then mash it to the floor, it would buzz up to about 90 MPH and start the bucking all over again. Back it off to about 75, then stomp it, she would pull to about 115 and buck some more. The problem was the stock fuel pump could not put out enough volume of fuel to keep the bowls full under hard acceleration. I removed the stock fuel pump, bolted on a Carter High volume unit, it would pull to 130 MPH and never buck at all, the H.V. pump could keep the bowls full

Asort answer, all 1966 thru 1991 V8 fuel pumps will interchance no matter what the cubic inch size of the engine is but stock replacement units are lacking for volume pumping ability when demand is put on them. Early cars like the 390 engines came from the factory with bolt together Carter high volume pumps.

Kind Regards,
Randy Guynn
Performance American Style

 

Sure the lower flow choked out a 390 with a 4bbl being romped on for continuous periods, but it moves more than enough fuel for a 304 with a mc2100. I've even found that off road, the "low flow" is too much and have regulated it down a few psi. I think the high/low flow point is moot for a cj.

My jeep has a hard line from the pump to the carb, so only one of the pumps would work without re-bending a new line. If you are not limited by that, either normal or upside down pumps will work fine for you. The bolt pattern is the same, just inverted relative to the connections. Most parts stores stock both.