Hi all,
I have a Pontiac LeMans, 1989 year of manufacture, engine 1.6 with Rochester TBI 700.
I think that I have a problem with a fuel pressure. Engine idling is bad. Engine idle has 800 rpm with fluctuation +/- 120 rpm and it uses a lot of gasoline.
Spark plugs are black with feathery carbon deposit.
I tested fuel delivery pressure with manometer.
Engine not running:
When the ignition is placed in the run position, the fuel pump works for two seconds.
1. The fuel pump works two seconds. I'm reading pressure: 0.8 bar (11.6 psi).
2. The fuel pump stopped. I'm reading pressure: 0.7 bar (10.2 psi).
Engine running:
3. The throttle is closed: 0.9 bar (13 psi) with minimal fluctuation +/- 0.01 bar (0.14 psi).
4. The throttle is wide open: 0.9 bar (13 psi) with minimal fluctuation +/- 0.01 bar (0.14 psi) - the pressure is not falling off.
In addition, I tested the fuel pressure regulator:
I started the engine for a few minutes. But at runtime, I'm reading pressure: 0.9 bar (13 psi). When I stopped the engine, pressure's down to 0.7 bar (10.2 psi).
After a few hours I'm reading pressure 0.7 bar (10.2 psi). This pressure holds where the engine not running.
Has the fuel pressure shouldn't be constantly at all times? - both when the engine is running and turned off.
Thank you for your help in advance.
