need help car starts but will turn off after a few secs

[JSM]

Also, don’t rule out a failing fuel pump. Would give you similar symptoms. 

Edited January 18, 2018 by JSM

[Reptoid Overlords]

The Harbor Freight tester JSM mentioned is a vacuum tester and fuel pressure tester in one, and its about 30$ if I remember correctly.

I've used it on my Z,Camry, and Volvo and it reads pretty accurate as all those cars run well.

You might check ignition timing as well. I bought Harbor freight's xenon timing gun for around 40$ too, and so far it works fine.

Good tools to have if you own a Z, or any older car really.

Sent from my [device_name] using http://Classic Zcar Club mobile

[Captain Obvious]

11 hours ago, JSM said:

don’t fuel out a failing fuel pump.

Haha! Fuel on the mind? 

[jesus]

18 hours ago, JSM said:

Also, don’t fuel out a failing fuel pump. Would give you similar symptoms. 

WHAT do you mean by that 

[jesus]

Fuel is flowing pretty good I changed the fuel filter at the front and still dose the same thing what este can there be other then fuel is there a fuse or relay that can go bad ? I heard that I could of shorted the transistor sys what else can go out if something like that happens ? 

[JSM]

Flow isn’t always associated with pressure. You could have enough flow to get the car to idle but not enough pressure to supply the needs for the engine.  A fuel pressure gauge will allow you to know exactly where you stand. 

[Zed Head]

When I first read your post I got kind of distracted by the 79 reference and overlooked the 1975 part.  Even though I copied a 1975 wiring diagram to my reply.

Your problem sounds like the fuel pump contact switch in the AFM is opening, due to low air flow through the AFM.  It's a common problem.  Could just be that it's running poorly and idle speed drops too much, or you have vacuum leaks in the AFM hoses or hoses to the intake manifold.  All of the hoses connected to the intake manifold and valve cover need to be connected and leak-free.  Even the oil filler cap and dipstick tube.  No air leaks in to the engine.  It's hard to grasp if you're used to working on carb'ed cars.

If you want to try to keep it running so that you can diagnose those problems, try opening up the idle speed screw to draw more air through the AFM.  If you want to get a quick check of the AFM fuel pump contact switch, either locate it in the AFM and put a jumper wire on it or have somebody hold the AFM wright open so that the switch stays closed.

The switch is tiny but you can actually see a tiny spark when it makes and breaks contact.  I think that that is your problem.  Here's a link and a picture from it.  From 240260280's work.

http://atlanticz.ca/zclub/techtips/afm/index.html

[JSM]

40 minutes ago, jesus said:

 

Edited January 18, 2018 by JSM

[Zed Head]

I'm guessing that you were pointing out that he said "fuel was flowing pretty good"?  Hard to tell when he saw the fuel flowing.

Everything could be set up perfectly but if he has one of the big hoses removed, like the PCV hose, it will start and die like he's describing.  Might just be a giant vacuum leak.

[JSM]

I quoted the wrong person, then couldn’t edit it out.  

It’s. always hard to internet help without being there. Plus I type so much better on my keyboard then my iPad!

[jesus]

7 hours ago, Zed Head said:

When I first read your post I got kind of distracted by the 79 reference and overlooked the 1975 part.  Even though I copied a 1975 wiring diagram to my reply.

Your problem sounds like the fuel pump contact switch in the AFM is opening, due to low air flow through the AFM.  It's a common problem.  Could just be that it's running poorly and idle speed drops too much, or you have vacuum leaks in the AFM hoses or hoses to the intake manifold.  All of the hoses connected to the intake manifold and valve cover need to be connected and leak-free.  Even the oil filler cap and dipstick tube.  No air leaks in to the engine.  It's hard to grasp if you're used to working on carb'ed cars.

If you want to try to keep it running so that you can diagnose those problems, try opening up the idle speed screw to draw more air through the AFM.  If you want to get a quick check of the AFM fuel pump contact switch, either locate it in the AFM and put a jumper wire on it or have somebody hold the AFM wright open so that the switch stays closed.

The switch is tiny but you can actually see a tiny spark when it makes and breaks contact.  I think that that is your problem.  Here's a link and a picture from it.  From 240260280's work.

http://atlanticz.ca/zclub/techtips/afm/index.html

ok sounds good i will try this hopefully it works i do have a feeling that its something to do whit injectors but i will give this a go 

[jesus]

7 hours ago, JSM said:

I quoted the wrong person, then couldn’t edit it out.  

It’s. always hard to internet help without being there. Plus I type so much better on my keyboard then my iPad!

haha yea i get you man thats why i get to you guys late because i work during the day and wait till i get to my computer. also i will see about the pressure