Z starting problems

[sblake01]

Try removing the fuel pump hose that draws gas for the tank and place it in a gas can so that it draws gas from the can. Then start the car and see if the pressure stays up and the car runs without bogging down. If it runs right then the problem is in the tank. If not then you have ruled out the tank itself and can work forward from there.

[sblake01]

Try removing the fuel pump hose that draws gas for the tank and place it in a gas can so that it draws gas from the can. Then start the car and see if the pressure stays up and the car runs without bogging down. If it runs right then the problem is in the tank. If not then you have ruled out the tank itself and can work forward from there.

[ALT_255]

so i ran the car mostly out o gas so taking off the hose from the fuel tank would be less messy, and now the fuel pump wont pump at all. i cant get the pressure to go over 10psi. is there something to do to prime it or does that mean i need a new fuel pump?

[sblake01]

The fuel pumps on these cars are self priming. Remember there are relays under the hood for the fuel pump so your fuel pump may not necessarily be bad.

[ALT_255]

how do i check the relays? and where are they located?

i checked the Fi book but it just says how they work

thanks

[sblake01]

http://www.classiczcars.com/forums/showthread.php?s=&postid=79937#post79937 and see how we helped work out Holly's problem on the 1st page up to the point where we started talking about u joints.

[ALT_255]

so i went out to the car today and this is whats happening:

so is there anything that would cause me to have to stick a wrench in the afm to get the fuel preasure up and then would let the car idle untill it was out of gas? but if i start playing with the throttle the car will die sooner..

very confused

thanks alot for all your help sblake

[sblake01]

Sticking a wrench in your AFM is NOT causing your fuel pressure to build. I suspect that you have a clog or blockage somewhere along with electrical problems that are effecting you fuel pumps' operation. It's really hard to diagnose without going through the steps. You have to confirm each thing step by step rather than guessing and replacing parts based on those guesses. When I had this problem it turned out to be a clogged gas tank but first I had to replace a bad fuel pump relay. Under the hood there are two relays that affect fuel pump operation (see pictures in other post) and there is also the ingition relay in the bracket on the passenger side kick panel which energizes those relays. When I worked on my car, I had the luxury of being able to take these relays from a properly operating car and plug them into mine one by one until I found which one was bad. At that point I knew the fuel pump was working and was able to determine that my tank was bad. It could be that if you have a relay problem and correct it that you don't have the tank problem. But you have to go through the steps.

[ALT_255]

sorry for jumping ahead

is there anyway to test the relays w. out having known working ones?

[sblake01]

I don't know of a way to test them. I always do my testing with known good ones. I can check them for continuity and get back to you with the results,but I don't know if that would tell the whole story since resistance is involved and in order to test that I think they would have to be energized. Maybe someone out there can respond if they know of an accurate way to test relays because I would also like to know.

[ChrisA]

If the relays are 12 volts to the coil. You could bench test them with a car battery. Use an ohm meter across the distribution terminals and fire the relay off the battery to see if it passes. I dont have a 280Z or ZX so I'm not familiar with the terminal arrangement on your relays. The factory service manual should show it. The wiring diagram might be printed on the relay itself also.

[mdbrandy]

Originally posted by sblake01

Sticking a wrench in your AFM is NOT causing your fuel pressure to build.

However, the air flow meter does have fuel pump contacts that only allow the fuel pump to run when the engine is running after the ignition switch reaches the "ON" position. Thus, it sounds like something, maybe one of those relays sblake is talking about is causing the car to think that the ignition is "ON", and since the engine isn't running, the fuel pump won't either. Pushing on the airflow meter flap makes the car think it's running (by changing the fuel pump contacts in the airflow meter), and thus allows the fuel pump to run, and the car to start.