2004 Toyota Corolla cranks but won’t start after long sit

Once the engine is started after more than 8 to 10 hours the engine cranks but does not start. However, if I attempt cranking within few hours 3 to 5 hrs, there is no problem.

Check the battery because It could be weak.How old is it?

If the engine cranks the battery is not the reason for a non-start. This car may need to get the “key dance” after it’s been sitting.

Thank you.
To give you more details see following:
1.The Battery is perfect.

  1. It it starts it does not give problem unless remains switched off for more than 10 hrs.

  2. All plugs new.

  3. Ignition coil is serviceable.

Fuel Pump Checked - OK & holding pressure.

  1. All HT leads perfect.

  2. Crank Sensor is OK.

  3. The first start problem happens 5 out of 10 times.

As per my Mechanic, the car has been running on compressed gas for quite some time. Therefore there could be deterioration of valves resulting in reduction of compression when the engine is cold. Later when the engine gets hot after it starts, the compression gets OK.

I request for an expert opinion.


Compressed natural gas? Not gasoline (petrol)? “for some time” = car was converted to CNG?

Perform a dry compression test on all 4 cylinders and report back to us, please

We’ll tell you if the values are acceptable . . . or not

A compression test is a good idea, but the theory that the compression is much less 10 hours later than 4 hours later seems unlikely. This sounds like a fuel pressure problem to me. Has the fuel rail pressure been measured when attempting to start at the 10 hour mark? It could just be leaking down very slowly. Often the spec is that it not leak down more than a certain % in 30 minutes, something like that. But in your case that might not be an adequate test method. If it isn’t a f uel pressure problem, then visually checking for a healthy spark at a spark plug during cranking when this happens is probably what I’d do. Also, a quick check to see if there is any gasoline in the vacuum line connected to the fuel pressure regulator makes sense. There shouldn’t be any.

Yes it had been running on CNG=Compressed Natural Gas.

The Gasoline car was converted and installed with CNG kit.

I would like to also inform that after having cranked the engine 8 to 10 times, I give a break of 10 to 20 minutes after which it starts in one or two cranks.
Could it be Valves or Fuel problem ?

If you perform that compression test, you’ll be much closer to answering one of those questions

You can always tee in a fuel pressure gauge, after you post those compression numbers for all 4 cylinders