94 300z won't start

[bossbob]

So, my son bought a 94 300z recently, the car broke down about 300 miles away from me. He said it just quit and wouldn't re-start. He was able to re-start it the next day, he changed out the plugs, at least 1 injector, and the fuel pump. Once he switched out the fuel pump it ran for about 20 minutes and the problem started again. He is 19 and limited knowledge. I'm 300 miles away and can't really help him from here. He's in So. Cal. near Lake Elsinore.

Any ideas on what he should be looking at. he's a little stubborn, and getting frustrated. Short of getting a trailer and towing it home I really don't know what else to look at. What are the chances it's a clogged fuel filter?

Thanks for any feedback.

[notoptoy]

I would check the gas cap to make sure it’s correct - possible it’s creating a vacuum if it’s not vented? Clogged fuel filter is not a bad idea. Was the car sitting for a long time? Perhaps the gas lines are gummed up, or the gas in the tank is bad?

[keith0alan]

The big question is what is going away when it stops? Fuel or ignition? You quickly get into electronic systems. I have run wires to fuel pumps and ignition systems and monitored them with meters while driving to track down failures. Not sure what version he has but the twin turbo was famous for cooking engine wiring harnesses and being a nightmare.

[bossbob]

I know he's run a few tanks of fuel through it, it drove fine for the 300 mile trip he took. It's not a turbo car. Don't know what's happening when it stops running. I'll have him check for spark again, when it won't start. I'm still guessing it's in the fuel delivery though. Just thought someone here might be familiar with these.

[Gregs672000]

There are so many possibilities... is it throwing any codes? Borrow a code reader from the local autoparts store (they will either allow you/them to use it in the parking lot, or allow you to take it home with a deposit etc) and see if the computer is noting issues.
Fuel, spark, compression: Can eliminate compression here. I believe you can listen to injectors to hear if they're firing using a stethoscope. Fuel pressure can be checked, or at least determine if its getting fuel. Spark should be easy to confirm. Could be a throttle position or cam angle sensor, or a crank angle sensor, maybe a mass air sensor (can be cleaned with electronics cleaner, but usually they just result in poor running, gas mileage issue or stumbling/acceleration issues). I'm not familiar with the engine but the basic electronics for modern cars are very similar to each other. I suggest a good or factory manual and a very pragmatic, step by step process of elimination.
I understand the frustration. However, express to your son that cars also teach patience and problem solving skills that help one out in life. Walk away when you need to when you get too pissed... the car does not care and will be waiting like Yoda for you to return and continue the training!
As a kid I watched a friend lose it and take a hammer to the fender of his 60 era Lincoln... and then he had to learn how to do body work. I too learned a lot watching that. The car, like life, doesn't care. If the angry energy gets too high, put it somewhere where it won't cause more problems, like a gym, wood pile, ditch or a punching bag until the energy level is down enough to be useful as an energy of determination and focus. Anger is like electricity: you can either use it to turn on lights etc, or stick a fork in the outlet and get burned... what matters is what you DO with it. Sometimes you have to regulate it down (220 volts down to 110 as is done in a house) before you can plug the toaster into an outlet, otherwise you will blow the toaster right off the counter! Thus the need for the gym or wood pile (and a good use of energy!)

Good luck, he'll figure it out and experience the happy energy of that too!

[greydog]

I think the '94s were still obd2 so may not be a lot of help. Nistune would be more help but unlikely he'll find anyone with that.
On my 90 300ZX, when the key is first turned to "on but not start, the fuel pump runs for a few seconds. Once the system is pressurized, the pump shuts off. It sounds like, for whatever reason, the relay that powers the pump is not getting a sufficient pressure signal.
I don't think the ecu will trigger the spark if the car thinks there's not enough pressure in the system.
Dan

[bossbob]

Thanks again, I think it's an obd1, he's knowledgeable enough to know that, as he has used my obd2 reader enough times. Yeah, tough times on the learning curve of life and cars. I'll talk with him later today and see how he's progressed and share this info with him.

[bossbob]

I guess he changed out the fuel pressure regulator, got it started and driving for 15 minutes or so and shut down again. Had him pull a plug, and he does have spark?

[redroadster]

Kd makes a spark gap testor $20 or theres a pen type, well worth it
Can spray carb spray in the throttle body. For fuel.
He hears the fuel pump running?
Mass meter bad? it may start but no power.
Valve Timing jumped from tight water pump?

[George H]

I believe they have a fuel pump module that runs the pump at 2 different pressures. I believe they can go bad. Take the fuel line off when it won't start and see if fuel comes out. Be careful. Recommend to point the hose in a container.

[redroadster]

A trans funnel makes a good stethascope stuck down the fill tube while someone cranks it to start the pump