The car doesn't start when cold and sometimes when warm until cranking for at least 4 or 5 seconds. Have tried new spark plugs and wires, spacers for spark plug wires to get rid of cross firing, and new MAP sensor.
I would check the fuel pressure. You may have a problem with the fuel pump relay or the one way valve in the pump.
Also, I have read that it could be leaky fuel injectors or a bad fuel pressure regulator.
That is true, but if the fuel is leaking into the cylinders, the plugs should not last long and it should run rough when it finally starts. clearing out the excessive fuel.
When I changed the MAP sensor I noticed gas on the old one which made me think of leaky injectors after I shut the engine off.
Right now it takes 3 to 10 seconds of cranking to start engine when cold. If it is hot it starts immediately. Unless it sits for 15 minutes in which case it takes 3 to 10 seconds of cranking for the engine to start.
I also notice that the RPMs vary from 650 to 750 to 950 after I put a bottle of stp fuel injector cleaner in.
The intake manifold is black plastic on the Northstar engine. I read that the intake manifold should be replaced when overhauling the engine because it is hard to determine if debris got sucked into the passages. But, I do not think this is my problem.
Sometimes it stalls when in gear and coasting. All this with no PCM code set.
Stephen is on the right track.
How can you tell the difference between a leaky injector and a bad fuel pump valve? I seem to have gas in the intake manifold when shut off. The MAP sensor was wet with fuel. Could this point to a leaky injector?
Again the rpm is unstable at idle ranging from 600 rpm to 1000 rpm the last time I ran it.
Depending on where the injectors are mounted, they usually leak directly into the cylinders. The fuel pump valve is a one way valve in the pump to prevent fuel pressure from going back into the tank. Nothing to do with liquid fuel in the engine. The fuel pressure regulator might be leaking into the intake tho.
I will check the fuel pressure regulator for a leaky rubber diaphragm.
I didn't even have to test the pressure to diagnose this one.
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SOURCE: emission problem 1996 sedan deville
I would suggest checking your Oxygen sensor which will light up your service emission light. Check that and let me know Good luck
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Stephen- Yes, I pulled the vacuum tube from the fuel pressure regulator on the stainless steel fuel return rail and it was dripping gas. I think this means the rubber is perforated in the fuel regulator, so I ordered a new one from Advance Auto Parts for $55.99 which should be here tomorrow morning at 7:30. In addition, it turns out that I can get a 20% off discount with a p20 coupon code off of the Internet. Good deal. Thanks for your help.
Only thing, is that the fuel pressure regulator has only a one year warranty, so if I keep this car, I can plan on replacing this part again.
glad you found it.
skychief2001 (stephen)- your commen led to the solution for me. I never changed one of these before on a 1990s model Cadillac. I heard that this happens on Suburbans from the 1990s as well.
'comment' rather than 'commen'
Starts up within 1 second now rather than 5 or 10 seconds. And, it wasn't getting any better with time. lol.
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