1999 chevy suburban 5.7 L. vortec. Can a bad camshaft sensor cause a no start? rebuilt engine, fuel pressure 60 LBS.,spark at all the plugs, compression 140 lbs, timing is dead on.

If your 1991 Chevy's 4.3 Vortec engine has spark and fuel, but still fails to ignite, there are several possible reasons to consider. Timing: Make sure the burn time is set correctly. Incorrect timing can prevent the engine from starting. Double-check the timing marks to make sure they align properly. Compression: Make sure the engine has adequate compression. If the pressure is low in one or more cylinders, starting problems may occur. A compression test will help determine this. Fuel Delivery: Even though you said it has gas, pay close attention to the fuel delivery system. Make sure the fuel pump is working properly, the fuel filter is clean, and the fuel lines are not clogged or leaking. Air intake: Inspect air intake for blockages or leaks. A clogged air filter or leaking intake manifold gasket can affect engine performance. Vacuum leaks: Check the vacuum lines and connections for leaks. A vacuum leak can cause an uneven mixture of air and fuel and cause starting problems. Sensors: The engine relies on sensors to send information to the computer unit (ECU). Defective sensors such as the crankshaft position sensor or camshaft position sensor can prevent the engine from stalling. Wiring and connections: Ensure all electrical connections are secure and non-corrosive. Damaged wiring or loose connections can block signals to engine parts. ECU/PCM: The engine's computer (ECU/PCM) can be faulty, preventing proper signals from reaching the engine components. Distributor cap and rotor: If your engine uses a distributor, inspect the distributor cap and rotor for any signs of wear or damage.

60--66 psi.
In my opinion. After it starts, it should run with less pressure.

The vortec engine has a time delay fuel pump relay, check that...Was your pressure reading with engine running?
Test your injectors. Check the coolant temp sensor, it will confuse the ECM if it is out of range...mainly when the engine is cool. Check the ignition for weak spark, coil resistance. Check the air flow sensor....I would stop using starting fluid immediately, the volatile conditions it creates could cause damage. Hope this helps.

If you have spark and fuel it should start. You must have min 57 PSI fuel pressure for this vehicle to start if it is the 4.3 Vortec engine. Also the cam sensor and the crank sensor control the spark. Does it have the check engine light on and if so what is the code or codes does it have? Need more info to help you out more.

No. The engine will still start, however if the sending unit is not working you will have no oil pressure and you will damage the motor and possibly lock it up. This vehicle can run with the unit not working correctly

Have you had the s10 scanned for the DTC codes. Auto Zone scan free of charge and this should help figure out why your loosing power when the engine warms up. You could have a faulty MAP sensor or a weak fuel pump, dirty fuel filter.

Not knowing what has been done, here is a few things you can do and check.

You may be weak on fuel pressure, even a couple of lbs low on fuel pressure can cause low performance.
Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems. Run the full fuel pressure test and post back pressures.
Here is the guide lines on testing.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

The 75-85 is only a check on the capable full pressure of fuel pump.
If you can not find the rubber return line check full pressure by plugging return line or just or the true full pressure can be taken direct at the end fuel filter.What are the pressure readings that you have done.
What are your cold start pressure readings?

You need 3 things.
Compression
Good hot blue spark to all plugs.
Good gasoline and proper fuel pressure. 63-64 lbs.
If you have all 3 then move on to injector pulse to all injectors.
I think each injector is on a separate driver on that one.
Check for pulse to all of them.

The next thing you can look at is the Cap and Rotor, inspect for any damages and corrosion which is common to accumulate in the distributor due the a clogged vent screen at the bottom of the distributor. That is where is ICM is located also and my be on it's way out and needs to be replace.

Best thing to do is check for any DTC codes at Auto Zone and that should help determine what is causing your loose or power. A bad fuel pump and dirty fuel filter will not trip any DTC codes.

Start with the simple and check all the fuses, the wire leads to the MAP sensor, it's located on the passenger side on the intake manifold by the throttle body. Check then check the distributor Cap and Rotor and replace, check the fuel pressure reading, and almost forgot to check the MAF sensor.

Try this in the mean time, turn you ignition to the run position "engine not running" and pull the fuse to your ECM for 1 min and place back in. Turn your ignition off for 5 sec and turn on again for 10 sec and then start the engine. It may stall out, let it. just start it again and let idle for 2 min and go for a test drive. This will reset your ECM to default and relearn all the sensors on the engine and transmission. Any DTC codes will have been erased and any DTC codes will be new to the issues your engine is having. Good luck and keep me posted, be glad to help you get your S10 running 100% again soon.

it looks like you need more fuel to start your engine check for a bad fuel pressure regulator, measure the pressure it should have 55 psi less wont start cold

Check the fuel pressure regulator, i'm not a 100% if the small block vortecs have one but if it does it will be on the top of the intake, near the throttle body.

THE FUEL PUMP IS BAD.

if your losing fuel pressure after the pump runs the drain back valve in the pump has failed.

and i doubt that you are seeing enough fuel pressure to run a vortec engine.

low fuel pressure equals a non running vortec