Looks like I need to replace a Fuel Pump.......

[dutchzcarguy]

18 hours ago, SteveJ said:

I used carburetor cleaner recently to spray down the vent lines. That works, too.

I used carb cleaner to on mine.. first i blew some compressed air and then some carbcleaner through the fuel inlets of the carbs..

(As there are airvents, (i checked that first haha)  on the carbs it's no trouble/problem to blow some air into them, in fact you can hear the air escaping from the airfilter inlet !! )

Then i connected the fuel inlets to the rail and the car started right up.

If i leave the car now for a few weeks then 1 or both are closed again and don't open.. it runs for 20 sec's and dies or keeps on stumbling on one carb or dies when 2 are staying empty..  Remedy is then to blow them with some compressed air or hit them with something like a little hammer or as cliff said a screwdriver handle!  IT WORKS!

To 70z4fun, I think i first replace my pump with one of my new ones to check if the new pump has a bit more pressure to open those little valves, and then i know 100% that those pumps fit a 240z..  but everything on those pumps say: i fit... 😉 

Oh and Steve, i will also prime the new pump by hand before i put it in the hole of the L24 block.. good call.

[dutchzcarguy]

11 hours ago, 70z4fun said:

Any idea who the manufacture of the fuel pumps that Z Depot or Motorspots are selling these days?

I don't think it's a Nissan pump.. ( one of the 4 makers that supplied to Nissan)  Otherwise they would have said so.. now it says "original look" 

[SteveJ]

11 hours ago, 70z4fun said:

Thanks for the information.

All fuel lines are new and tight. 
Any idea who the manufacture of the fuel pumps that Z Depot or Motorspots are selling these days?

 

The diaphragm or one of the check valves may be going bad. What brand pump do you have on the car now?

[qz16]

MY car was not being started regularly as I was in the middle of restoring it.  I had heard that there were issues with new fuel pumps.  I bought 2 before I finally took a friend's advice.

Background: 

Fuel tank restored
Hard and soft fuel lines replaced
Carbs restored
I filled the fuel bowls, and it would run for a bit
I filled the fuel filter and bowls, and it would run
A few days after shutdown I noticed that the fuel filter bowl was not full, a few days later it was empty.  Would not start, would not fill fuel filter bowl.  I was convinced that the pump was not strong enough to pull fuel from the tank to fill all the lines and the fuel filter.  As part of troubleshooting, I used a jerry can and short hose to simulate the tank and hard line.  Could not pull fuel to fill the filter.  There was some information regarding the amount of vacuum created by the pump, so I measured the pumps.  Sorry but I forget the results and have lost my notes.  An old school method to test a mechanical fuel pump is to put it in a vise and work the arm.  If it wheezes it supposedly is more likely that it is ok, if not it is supposedly bad.

 

Solution to my issue:

A friend told me to recheck all of the hoses from the fuel filter to the carbs.  I did that everything seemed tight.  I replaced all of the hoses and this time I used the correct diameter.  It was more difficult to connect the right diameter, they seemed overly tight.  When this was done, I once again filled the fuel filter and the float bowls.  It started and I have not seen the fuel filter bowl empty since, that was 7 or 8 months ago.  The car has not been restarted due to other work on it that I am doing.  My story is not complete – I never did put the original pump on to prove that it still had life.

 

Bottom line:

I am sure there are some bad fuel pumps out there, and I am not saying that you don’t have a bad fuel pump.  This is what seemed to solve my problem.  It was difficult for to believe it at the time, but as the months went by and the fuel filter remained full other issues became more pressing.  The car starts now even after long periods of storage.

 

Hope this helps.

[siteunseen]

I learned the hard way like you did, you must us the millimetre size hose on a 240. Low pressure hose to, it's a lot cheaper the EFI hose.

280s are a little more forgiving with 5/16" since they have the higher pressure PSI. If they are not not right you'll get a spray of fuel when the pump comes on.

[70z4fun]

Quick update.
Got the car started by filling the carb bowls.

Moved it in the shop. While it was running, the fuel filter was getting some gas.

I decided to replace the fuel lines again, based on what I have read on this forum. Going to go with metric braided hose with new clamps.

The current fuel pump on the car Kyosan Denki. IS there a rebuild kit with replacement diaphragms?

Maybe the fuel pump is ok? 

[qz16]

Perhaps you should consider making one change at a time.  The rebuild would be last on my list.  Just a thought for what it is worth.
 

[70z4fun]

Good point, I will replace the lines first.

Can't seem to find a rebuild kit any way..........

 

 

[w3wilkes]

I've been running 5/16" on the supply side and 3/16" on the return side (Gates E85 rated low pressure fuel hose) since 2017 and have never had an issue, even when car sits for months over the winter. Fuel filter stays full.

[Zpenman]

I know I'm late on this topic, just wanted to reaffirm the need to prime the new fuel pump before installation. Had quite a mess in the garage chasing phantom hose connection leaks and the possibility that the new pump being installed was faulty. Removed the pump, manually primed it with a water bottle filled with gas, and voila, works like a charm. Should have remembered this 40-year-old lesson from my Dad, but hey, getting a little older.

[70z4fun]

I have not had an issue with priming the pump. But I do keep feel in the tank to help.

Proper fitting lines help with restricting air......

IF your lines are empty, using a vacuum pump helps too.