1973 240z Fuel Not Flowing

[Tirnipgreen]

There was an electric pump fitted by the dealer after the car was purchased...I have the receipt. I installed a new mechanical pump on the head. The old electric pump was by-passed years ago...maybe I should bring it back into operation...? I like that it had another filter incorporated in the bottom sector of it. Before I do any bodywork to this Z I want to get it running right and reliable...and driving right with full suspension rebuild. Where can I get new springs...?

[gwri8]

Welcome!  I'm not a whole lot far from you. Maybe an hour or so....

Mine is a 77' with EFI so I'm not really a carb guy,  but I've done a couple of fuel tanks and like everyone here,  quite familiar with our friend Mr. Rust.

How long did the car sit?  and where did it sit,  inside or outside?  It is not uncommon at all for the tank to have rust an crud in it after sitting for extended periods (or decades).  Fuel pumps, fuel lines  and carbs can also suffer as well as everything else.  In all likely hood,  you will probably end up dropping the tank to at least clean and visually inspect the inside.  I think that would be a good place to start, then work your way up the fuel lines to check for any corrosion/ blockage there.  That will lead to the fuel pumps, filters and hoses and then of course the Carbs.  It sounds like a lot but it's really not and will give you piece of mind and knowledge of your complete fuel system.  IMO,  it's all going to have to be done sooner or later. 

The people on this forum are a very deep well of Z knowledge, both historically and mechanically.  Somebody will have an answer to whatever you're going to have a question on.  You've come to the right place.

[SteveJ]

10 hours ago, Tirnipgreen said:

There was an electric pump fitted by the dealer after the car was purchased...I have the receipt. I installed a new mechanical pump on the head. The old electric pump was by-passed years ago...maybe I should bring it back into operation...? I like that it had another filter incorporated in the bottom sector of it. Before I do any bodywork to this Z I want to get it running right and reliable...and driving right with full suspension rebuild. Where can I get new springs...?

The electric fuel pump is essentially a helper pump. It's only running after the car has started.

Have you replaced all of the soft fuel lines under the hood and going back to the tank? Old hoses crack and let in air. The symptoms would be similar to what you described. It could also be a mechanical fuel pump with a damaged diaphragm. If you have replaced the soft lines, I suggest changing the mechanical fuel pump out. There are several choices for mechanical fuel pumps at Rockauto at $35 and less with similar parts & prices at Amazon, so it's not a big expense.

I can probably come up to see you in a couple of weeks to give you some suggestions about sorting things out on your car, too.

[Tirnipgreen]

OK....not sure if this will get back to anyone or not, but I had the tank cleaned, sealed and painted. The smaller vent on the top of the tank broke off when I lowered the tank so I had the shop cut it out and weld in a plate. Did I do something bad...? Should I plug the vent line that was attached to that tube before reinstalling the tank...? Should I take the tank back and have them add the tube that I had them remove...? I'd love to get this thing back together today to see if my fuel issue is now solved...Ryals

[siteunseen]

My reason for saying this is a lot of people have plugged all the vent lines trying to get the gas smell out of their hatch.  Another reason is they have plenty of "vents". 

Is it the 10mm one in this picture?  If so I think you'll be okay but then you have the other end of the hose that went to it to deal with.

It'll be #7 in this drawing and connects to the bottom of the evap tank in the hatch.  If you can find the tank end of that hose stick a bolt or something inside it to seal it off.  Those tanks may build up enough vapor to form some liquid that could drip out.

Edited March 29, 2018 by siteunseen