99 expo 4.6 trouble

[Experez]

Have you try an iac valve??

 

[toms89]

I have cardboard between maf and filter. Computer is reset after every sensor change. The engine lopes worse with maf unplugged. Idles smooth maf plugged in and half covered.

If you are running it with cardboard between the maf and filter you are altering the airflow. I assume you are forcing more air to go across the sensor element. This will "fool" the pcm into believe the airflow is higher than it really is.

This will cause the 1121 code as you admitted to because the airflow doesn't match whats typical for a closed throttle position.

The 1151 code indicates idle speed is too high or out of range. Did you tamper with the throttle stop settings?? This could cause a 1151 code if its opened too much. Try disconnecting the iac valve and see if idle speed changes. If not it may be a faulty iac sensor, wiring, vacuum leak, or too much idle air getting past the throttle plate.

Altering the airflow through the mass air sensor is masking the problem and likely setting invalid codes. If neither code is valid I would suspect vacuum leak or failing fuel pump just due to the fact you are tricking the pcm to add more fuel by increasing pulse width. This indicates you have a lean condition.

 

[46expo]

Ok so i removed my card board. It is hard to start had to use starter fluid. Once running it barely runs hit it with starter fluid it revs up. No codes though cant put in gear will die. Could this be a weak pump? Filter has been changed. Sock looked good when i droped the tank.

 

[toms89]

I would suspect major vacuum leak or weak fuel pump.

Reset the pcm & ..

Check your fuel pressure at the rail. Since it barely runs the reading should be obviously low if fuel pressure is the problem. Look for a minimum of 30psi @ idle.

Check and see how much vacuum you are pulling at idle. I would look for 16-20 inches at idle. This may not work well if it barely runs as it will be skewed low.

Go from here and let us know your results...

 

[ArtGamer60]

That is what i was thinking a good ole vacuum gauge just to see ... +1

 

[46expo]

I would suspect major vacuum leak or weak fuel pump.

Reset the pcm & ..

Check your fuel pressure at the rail. Since it barely runs the reading should be obviously low if fuel pressure is the problem. Look for a minimum of 30psi @ idle.

Check and see how much vacuum you are pulling at idle. I would look for 16-20 inches at idle. This may not work well if it barely runs as it will be skewed low.

Go from here and let us know your results...

Im leaning toward fuel pump. I believe i would hear a leak that bad.

 

[toms89]

I would suspect major vacuum leak or weak fuel pump.

Reset the pcm & ..

Check your fuel pressure at the rail. Since it barely runs the reading should be obviously low if fuel pressure is the problem. Look for a minimum of 30psi @ idle.

Check and see how much vacuum you are pulling at idle. I would look for 16-20 inches at idle. This may not work well if it barely runs as it will be skewed low.

Go from here and let us know your results...

Im leaning toward fuel pump. I believe i would hear a leak that bad.

Just my theory based on what I am "understanding" to be happening but internet diagnosis is no replacement for actually being there. There could be many potential causes to your particular issue.

I would highly recommend testing before replacing any parts!! The results of the test would lead me or others hopefully to the next appropriate step to take.

 

[46expo]

I wont be able to get a fuel pressure gage til ltommorow . But was wondering whats the gph on the pump. When i drain the tank it took 3-5 min to fill a 3 gal bucket it did seam kind of slow to me.

 

[46expo]

Update. 22psi at cold start up. Barely got that. Unplugged vacuum from regulator no change. Turn engine on turned key to prime no change. It does hold that pressure off. Fuel pump it is. Never heard of an electric pump get weak. Either work or not. Thanks for the help

 

[46expo]

Pump intalled all is wel. Again thanks