280Z rebuilt fuel system - engine just stops!!!

[widget777]

I have a 78 280Z which I have owned and rebuilt over the last 15 years. Before the major renovation noted below was done, the car ran fine. Recently, I tore my fuel system apart and replaced most of the system with new components (List will follow at the end of this set of my comments). The car starts great and runs great for about 5 miles (in the Washington state winter), then stops. There is no sputter or hesitation before it stops running. The engine stops as if I have shut off the key. It will not start again until the engine cools off. I originally suspected vapor lock so I have insulated all the fuel lines in and around the gas tank and fuel pump areas plus all lines in the engine area. Some areas, I installed heat shields.

The components that I have replaced include:  New fuel tank, new fuel gauge sending unit, all flexible fuel lines, new fuel pump and fuel damper, Fuel pressure regulator, fuel injection relay for pump and engine components. I also installed a 100 micron fuel filter between the new tank and the new fuel pump. Lastly, I put in a new check valve in the gas breather system.

after I installed all components, I still had the problem so I took them out to make sure that the filters and pumps were working properly. After re-assembly, the problem still occurs. Fuel pressure is set at 38PSi with the engine not running and 32psi with the engine running.

 I wonder if the problem is related to  the engine coming up to temperature????? I also have done some renovation in the engine compartment to install the new fuel pressure regulator.

Can you folks offer any suggestions regarding next steps for me to take?

[widget777]

My cell phone is 360-220-0799 if you have any questions regarding my post for help

[kickstand80]

So what is missing from the list of things needed for the engine to run? Air, Fuel or spark? Make this happen again and then check to see if you have spark. this will narrow it down.

[siteunseen]

Try pinching the fuel hose before the metal fuel filter by the charcoal cannister on the passenger's side. It should be as hard as a rock on the bottom hose going into the filter and just as stiff up top coming out of the filter. Easy way to check that filter. I had a clogged up filter and it would run for a few minutes then after the sediment fell back down it would run again but only for a few minutes. Good luck finding your gremlin.

 

[Zed Head]

2 hours ago, widget777 said:

new fuel pump

 

2 hours ago, widget777 said:

fuel injection relay for pump and engine components

 

2 hours ago, widget777 said:

100 micron fuel filter between the new tank and the new fuel pump

 

2 hours ago, widget777 said:

new check valve in the gas breather system

Might be that the pump itself is overheating and locking up from trying to pull through the filter.  The factory only used a coarse sock in the tank.  The pumps are designed to push, not pull.  Might be worth a test with the filter removed.

The new relay could be overheating also.  It happens with the old orgiinal relays.  If you can test for voltage at the pump it might tell you if it's electrical.  Also test for voltage at the injectors if you changed the EFI relay.  Or just test anyway, maybe you have a new problem not related to the parts you changed.  1978 had two separate realys, fuel pump and EFI.  Earlier years had the two combined in to one unit.  Not clear which you changed.

And, of course, if you have the old parts you can swap them back in and see what happens.

 

The heat soak problem with the EFI engines usually manifests as hard starting, then running like crap for about 20 seconds that feels like 20 minutes.

[Captain Obvious]

5 hours ago, widget777 said:

Fuel pressure is set at 38PSi with the engine not running and 32psi with the engine running.

Is the fuel pressure still at 38 psi when you are cranking it after it has stalled? If so, it's not a fuel pump or tank issue.

It would (should) be relatively easy to narrow it down to fuel or spark. Since it just shuts off, I'll rule out air and ignition timing. But it should be relatively easy to determine which of the other two is causing the issue.

Next time it stalls and won't start, pull the center wire off the distributor cap (the one from the coil) and lay it close to the nuts on the strut mounting point. Slide the rubber boot up the wire a little bit to expose the metal contact inside. Then crank the engine and see if you have spark from the wire to the strut nut.

[Zed Head]

Those are good points.  Another that comes to mind is to pull the small wire from the starter solenoid, the one with the spade connector, and turn the key to Start.  The engine won't crank but the fuel pump should get power.  It's the Nissan recommended fuel pump test.  Usually you can hear it run if it's running.

[widget777]

I want to thank all the folks that have commented on my problem. I am working through the suggestions as fast as a 78 year old DIY guy can, so be patient with me please. It is nice to know that there are folks that are will ing to suppport my project with welcome advice.

[widget777]

To Zed Head.

I replaced both relays. They come as a set from Z Car Depot.com

[Zed Head]

I would find a way to check if the pump has power when the engine won't start.  You could check at the relay or check at the pump itself.  If there's power, make sure the ground is good.  If there's power and ground you have a pump problem.  Otherwise you have an electrical problem.

Many places to check the circuit.  The wiring diagram shows bullet connectors somewhere along the way.

And, ZCarDepot has done a great job of building his business.  But, like all businesses, he has to try to find the lowest cost parts in order to make a sufficient profit.  Could be a bad relay.

[widget777]

I can hear the pump running after the engine dies so I think that the pump is OK. This is the second new pump that I have installed since I have had this problem. I am going to change teh fuel filter in the engine compartment and see if it will solve my problem.If not, the next step is to remove the primary filter that I installed between the tank and pump.

On another note, there are 2 sensing devices on the thermostat housing. Could either of those be the cause when the engine comes up to temp??, The temp gauge shows normal temp when the engine is running before it fails.

[siteunseen]

There's a simple way to check that metal filter up front but they are only $20 so couldn't hurt replacing it anyway.

 

Try pinching the fuel hose before the metal fuel filter by the charcoal cannister on the passenger's side. It should be as hard as a rock on the bottom hose going into the filter and just as stiff up top coming out of the filter.