76 300d primer pump stalling the car!

[mac2]

The blasted thing keeps getting stuck in the depressed position and then it kills the engine. It does eventually go back up if you let the car sit for awile but as soon as it is started within five minutes it has sucked back down and the engine is dead. I talked to the people at Napa and their books don't go back to 76 and so they have no idea. I looked it up on fastlane and it didn't list one for my model year. This basically leaves me stuck with a dead car. The attached picture is of the primer pump and since it's on the fuel filter I don't think the new style will work.

I don't know a lot about 115s, but is it possible that it is being sucked down because a restriction someplace (like the tank strainer) is causing a vacuum in the fuel supply line? Just a guess.

[mac2]

I think you're right on the money about a fuel-line obstruction, I've replaced all the filters except the inline one. Suprise.... it's clogged! In fact it's black with scum. I'll replace it in the morning when Napa opens. Thanks.

[TonyFromWestOz]

Originally Posted by mac2

I think you're right on the money about a fuel-line obstruction, I've replaced all the filters except the inline one. Suprise.... it's clogged! In fact it's black with scum. I'll replace it in the morning when Napa opens. Thanks.

mac2, That filter is a cleanable one.
Unscrew the ends to remove the screen and clean it with soap and water and a toothbrush.
I had one of those, but it clogged up about 10* faster than a cheap inline filter.

[t walgamuth]

tell from you r pic but is the primer pump the old style? with a thumbturn on top of a thing that looks like a big syrenge top? if so, when done pumping you are supposed to lock it down by screwing it clockwise at the bottom of its travel until it wont turn anymore.

i dont know what the result of its being not locked would be but an air leak into the fuel line seems like a good possibility.

tom w

[t walgamuth]

i see it is not on the injection pump. i dont think that this is a factory setup. i would suggest getting whatever the factory setup was and installing it. this non factory prime pump seems very suspect to me.

tom w

[mac2]

It is the factory setup, although they only used this particular design on the 75 & 76 300d (It's a great car but there are enough differences from the w123's that finding certain parts can be troubling) Besides there is no provisions to mount a primer on the injection pump. (that is where they mount on the w123 right?)