Fuel pumps failing

[wolffcub]

In the last 1000 miles I have gone thru 2 mechanical fuel pumps. I'm using the Airtex 4149. What seems to be happening is for some reason the pump arm that rides on the lobe seems to get stuck in and only returns out a fraction of the way. When the pumps were new the arm would fully extend allowing a full compression stroke and full return stroke to properly pump. If I let it sit for a while the arm seems to pop back out to its full outward position. even with all the lines disconnected and pumping it by hand it will still not fully return outward all the time.

Was I lucky enough to get 2 bad pumps?

[1project2many]

Airtex is not what it used to be. Unless you're managing to get the arm of the pump wedged during installation, I wouldn't be surprised to find the pumps are both nfg.

[imjeff]

Is your line from the tank to the pump clogged or collapsing?

[wolffcub]

it is all new soft line from the tank to the pump and i did not see any collapsed areas. It seems to be free flowing from the tank to the pump. The tank is properly vented to balance pressure. Like i said even with the supply line disconnected from the pump it will not allow the arm to fully extend.

[Speedbumpauto]

The rod length is 5.750". Eliminate that first.

[OrrieG]

Or slightly bent or galled rod....

[_Ogre]

the top bolt on the front motor mount goes into the oil pump rod cavity
if you use too long a bolt in that hole you can restrict or no strict the pump rod
it is also very handy to put to long a bolt in that hole for holding the rod while installing the pump

also try a different manufacturer pump

[wolffcub]

Little confused what people are referring to as this "rod" Maybe im just not on the ball today but the pump rocker arm rides directly on the cam lobe. What is happening is the rocker arm for some reason does no always want to return to the full out position thus not following the cam lobe properly. The rocker arm is only returning out a fraction of what it should so its doing the smallest little pumps as the cam lobe high spot comes around.

[wolffcub]

i can stick my finger in the fuel pump mount location and there is no restrictions anywhere near the lobe or pump rocker arm. The pump rocker arm does show some contact wear where it rides the lobe so it has been working correctly before. My fuel pressure gauge just ever so slightly bounces up and down at .5 psi as the pump makes its short pumps.

[Old Crow]

All those posts with reference to the push rod are refering to the fuel pump on a small block. If I recall, you're running a straight six.

[wolffcub]

My bad. I forgot to list that it was for a 1955 235 inline.

[_Ogre]

a little info in your signature line will stop that
look in my signature to see how it's done