It has happended a couple of time so far.. It will crank but will not start unless I crank on it for a couple of minutes, I just bought the car so dont kow allot about it.. Did have it scanned today but it just came upthe egr was bad and the o2 senser showed low voltage, would either of these cause the problem?
96 Neon sometimes will not start
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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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17,269 Posts
Yes. Although the O2 sensor isn't directly involved with mixture control until the engine is warm, rich operation can foul plugs (black tips) and cause hard starting.
If the egr is leaking, it can cause hard starts and rough idle.
Take care of these known problems first and the continue with diagnosis if needed. A fuel pressure gauge screwed into the rail test port should show ~ 48# pressure at key-on.
If the egr is leaking, it can cause hard starts and rough idle.
Take care of these known problems first and the continue with diagnosis if needed. A fuel pressure gauge screwed into the rail test port should show ~ 48# pressure at key-on.
Ok checked the fuel pressure and when runningit is at 51 psi.. Also did the check on the egr valve. Book said ot apply 5 pounds of vaccum to it while running, if idle drops or it stalls then the egr is working correctly. Which it did.
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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17,269 Posts
The fuel pump should run for a second, then shut off when first turning the key from off to run. You should be able to hear the 'hum' in the back to confirm this. It will only resume pumping when the PCM sees a crank position sensor signal indicating that the engine is turning.
There is a one-way check valve in the fuel pump to keep a residual pressure in the system for the next start. When these check valves fail, the fuel drains back into the tank and a long crank time is necessary to prime the injectors with fuel again. A rapid drop in pressure after turning off the engine would probably be a failing check valve.
If you erase the fault codes with a battery disconnect, do they return? If so, then they are probably real.
The EGR transducer is the black plastic disc with the EGR vacuum hoses on it. A new one comes with the EGR valve.
The O2 fault code should tell you if it is the upstream or downstream O2 sensor.
There is a one-way check valve in the fuel pump to keep a residual pressure in the system for the next start. When these check valves fail, the fuel drains back into the tank and a long crank time is necessary to prime the injectors with fuel again. A rapid drop in pressure after turning off the engine would probably be a failing check valve.
If you erase the fault codes with a battery disconnect, do they return? If so, then they are probably real.
The EGR transducer is the black plastic disc with the EGR vacuum hoses on it. A new one comes with the EGR valve.
The O2 fault code should tell you if it is the upstream or downstream O2 sensor.
Ok all of this makes sense to me.. Where is the check valve located. I look in the book but dont see any check valve.. Would that be a part of the pressure regulator.. And I dod have the codes cleared and the light did come back on. And i do want to thank you for all of your advice
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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17,269 Posts
Unfortunately, the check valve is integral with the fuel pump assembly and is not serviced separately. If this is what is happening, replace the fuel pump.
If it can hold 10 psi in the lines and fuel rail, it may be OK.
Is the hard start only after sitting overnight if the pressure drains down to zero?
If the tank, fuel and brake lines back there are rusted, disturbing them may start fluid leaks. Be prepared for having extra work because of replacing a fuel pump.
If it can hold 10 psi in the lines and fuel rail, it may be OK.
Is the hard start only after sitting overnight if the pressure drains down to zero?
If the tank, fuel and brake lines back there are rusted, disturbing them may start fluid leaks. Be prepared for having extra work because of replacing a fuel pump.
UPDATE: Just changed out the fuel pump and gas tank.. When i was under the car checking out stuff I noticed the tank had a big dent in it so figured might as well change it now.. It seems to run better and does seeem to start like it should.. But i have only driven it a few miles, so over the next couple of days will tell the story if that was the problem.. Again thanks for the advice.
Well day 3 and the car will not start. Went to start in to go to work and it cranks but wouldnt sart. When I got home I ran a couple of test on it, one was putting an in line spark tester and I get no spark.. I havew been reading other post on here about others having starting problems, am now kind of leaning towards the crankshaft positionor senser being the problem.
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
Joined
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17,269 Posts
The crank position sensor can cause no spark issues and can be intermittant and not throw a fault code.
It would be sweeter if it could be confirmed failed with a scan tool during a no-start, but they are cheap enough for a 'Hail Mary' try.
It would be sweeter if it could be confirmed failed with a scan tool during a no-start, but they are cheap enough for a 'Hail Mary' try.
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