hard start when hot!!

[zin999]

Hi all i have a 92 na 300zx. Just got it after it had been sitting for 7 years. The person b4 me has not set the timeing when they changed the water pump sooo 12 new intake valves. I have gotten it running, but when I start it in the morning it starts fine. any time after the first run for the day if i hit the key it starts but dies after 2 sec with no gas. If I hold the gas mid-way for about 10-20 sec it will go to idle. the tach is not working when started it goes to 3k and stays unless at high rpm and it drops to 0 if it is relevent. It also seems to be eating alot of gas also. thanks for any help.

[BigTDogg (MA)]

Hi all i have a 92 na 300zx. Just got it after it had been sitting for 7 years. The person b4 me has not set the timeing when they changed the water pump sooo 12 new intake valves. I have gotten it running, but when I start it in the morning it starts fine. any time after the first run for the day if i hit the key it starts but dies after 2 sec with no gas. If I hold the gas mid-way for about 10-20 sec it will go to idle. the tach is not working when started it goes to 3k and stays unless at high rpm and it drops to 0 if it is relevent. It also seems to be eating alot of gas also. thanks for any help.

If they botched something as simple as a timing belt job, I can't even fathom what else they funked up.

Your PRVR system could be giving you hot start issues, but that would be my guess for a previously functioning car.

Might want to check for members in your area and see if they can help you diagnose it.

Welcome to NICO!

[zin999]

So what drives the tach? the ecu?

[zin999]

If they botched something as simple as a timing belt job, I can't even fathom what else they funked up.

Your PRVR system could be giving you hot start issues, but that would be my guess for a previously functioning car.

Might want to check for members in your area and see if they can help you diagnose it.

Welcome to NICO!

ok please forgive my ignorance but PRVR?

[BigTDogg (MA)]

PRVR = pressure regulator vacuum release

Quote ChristopherTheOne nevermore:

"The only function of the PRVR system is to cut the vacuum signal (hence PRVR=pressure regulator vacuum release) during the first 30 seconds of engine operation when the fuel temperature in the rail is >= 75C. After 30 seconds, the solenoid disengages and manifold vacuum is restored to the pressure regulator.

The idea is that when fuel temp gets up that high, the density has been decreased by the heat so the PRVR cuts off the vacuum to the FPR (Fuel Pressure Regulator, exposes it to atmospheric pressure, actually) thereby increasing pressure in the rail to the standard 43.4psi and ensuring ample fuel flow to run the engine smoothly.

To bypass the system, one would simply reroute the vacuum line from the plenum directly to the FPR instead of to the PRVR solenoid. The FPR will constantly be exposed to manifold vacuum, then.

It's a useful trick if you have a vacuum leak you can't isolate, like in the PRVR check valve or vacuum tank (which is inside the driver's fenderwell...a real PITA to get to)"

[zin999]

ty vm that fits the symptoms after i start if i hold the engine reved for about 30 sec it will idle fine.

[BigTDogg (MA)]

NP. he's a smart guy from another forum.

[zin999]

well ok i found a vaccum line i missed on the prvr runs smoother as a whole but still same thing have to hold it reved for 20-30 sec b4 it will idle even with the prvr bypassed ecu problem mabey?