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Discussion Starter · #1 ·
My car aparently vapor locks whenever hot. I can stop go in a store, and when I come out the car refuses to start. Only after popping the hood and letting the motor cool for five to ten minutes does the car finally start. I replaced the factory fan with a high flow electric fan recently and the problem seems to be worse. I thought about putting one of the later model fuel injection blowers on it (I have the parts). The car is a 78 and has a vented hood.
 

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RE: check vacuum valves

There are lots of things that can go wrong in the 280Z (Most vital parts collapsed simultaniously in my '78 280Z when it turned 20!)
There are a lot of vacuum linings in this car, but start checking the EGR valve by have a friend idle the car and let him rev it to approx 3000rpm. Meanwhile, check with your fingers underneath the Vavle and feel for movement. While idling, the engine should shut down if pressing the diaphragm under the EGR valve.The Back Pressure Transducer (BPT) is connceted to the EGR and is preferrably checked by detaching the hose between them (disconnect the hose from the EGR pipe!) Put finger in hose and let, for instance same friend accelerate car to 3000rpm. Vacuum should be felt by your fingertip.
If failure is noticed, new valves are recommended instantly.
To the BPT there is also a thermal vacuum valve, which is, if engine has been dismantled, easy to fit the wrong way around. Its the hose leading from the BPT and forward. If its okey, disconnect from BPT and rev engine. No vacuum should be felt here.
If your car is sold in California, there is also a Vacuum delay valve, that is located, between the EGR and the throttle chamber. Never seen such model, though (Mine is sold new in Florida, and now residences in Sweden, where there are noone else to check with!) Also check all linings for cracks, that can save a lot of trouble. (Rubber hoses are cheaper than complete valves...)
Have vacuum and fuelflowing diagrams and separate fuel injection wiring schedule for this cars.
Let me know if needed.
Hope it works out
Marten Carlsson Sweden
 

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I also have the same problem let me know if you fixed it and what you did. (I've replaced the spark plugs, wires, distributer cap, and rotor so far)
 

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Your engine won't run properly as well?
The ignition system is quite reliable, I would immediatly start checking out the vacuum system.
I had my 1978 280Z belching tremendous amounts of black smoke last summer (I mean it blackened out the entire garage!)After a long struggle with the pedal, it painfully got to 2500rpm, and died when I put the gear in. This depended on a faulty thermoswitch. (located at the front of the thermostat) How this switc could cause these prioble still puzzles me.
The L28 never stops to amaze me...
The only thing to do, systematically check everything, piece by piece.
takes time, but what else...

Good luck Marten Carlsson Sweden.
 

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Discussion Starter · #8 ·
I did inspect the vacuum lines and one I replaced a week ago had split where attached to a v.valve. I fixed it and will see if that's it. I had a couple of split lines but it showed up mainly as failures of the hvac vacuum motors (defrost x-work).
 
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