Just because you have a new pump and regulator doesn't mean your getting sufficent pressure. Is your engine a vortec or just a throttle body?

 

New fuel pump, & regulator does not mean that you've got proper fuel pressure. And with today's fuel systems having to have 55 pounds of pressure to 65 pounds of fuel pressure before they will start, you cannot tell if it has 55 to 65 pounds of pressure without a pressure check.

 

TBI people!! Which means he needs 9-12psi. If the pressure were too high (say from a wrong pump for the application), it could cause a rich condition.

And you have changed the MAP sensor, but did you test the wiring? A wiring problem could be telling the ECU that the engine load is a lot higher than it really is.

 

I changed the MAP, i have also checked the voltage on the MAP. I have 5V and I got the proper reading on the sensor. Is there anything else to check besides that.

The symptoms I have are the same as they were when it started to foul up. Fuel pump should be the correct one.

From the beginning I got error codes on the MAP and that the O2 sensor showed a rich condition. It hasn't run that long yet for the error codes to show up but it runs really rich now, just as it did when I started working on it.

Thanks

Jan

 

I even looked back at his 1st post, read it plump thru again saw no where in it weather it was a TBI, of course paid no attention to his signature where it was plainly disclosed.

 

Is this the same truck you have been having drivability issues with since August of 09?

 

Could be the EGR valve stuck open?


If the "check engine" light does not illuminate or yourcar does not have a service light, you can still use your mechanical ability to determine if the EGR valve is working. There are two possible malfunctions of this valve. It is either not closing when it should or not opening when it should.
NOT CLOSING. If the valve does not close, the engine will idle rough or stall completely when you remove your foot from the accelerator. It may also hesitate when you try to accelerate. These are the same symptoms as a vacuum leak so don't assume the EGR valve is at fault. You must test it.
NOT OPENING. If the valve does not open, you will notice a small reduction in horsepower. The engine may knock or "ping" under acceleration. It may run a little hotter and seem to labor under load. You may also notice

 

tbi iac valve stuck would cause it to choke when touching the gas pedal and check your tps always use gm parts if u use autozone parts your asking for trouble

 

Not mine


The EGR valve is moving when the engine is cranking.

A frined of mine had a similar problem on a TBI V8 car were some obstruction in the fuel return line restricted the flow. I will check that.


Jan

 

I am thinking you may need to start from ground zero. Is the engine in good condition mechanically? What is the compression in all cylinders? how many miles? what about the timing chain?
Do you have anyone else that can work with you? sometimes a fresh set of eyes can spot the obvious that you have been overlooking. Believe me - Ive been there!