2000 Bonneville only getting 10 miles per gallon

[Realtree11]

So I have a 2000 SE and I'm only getting 8-10 miles per gallon and it misfires. I have put new plugs, new spark plug wires, and all new coil packs and it's still misfiring so bad the car shakes like crazy when parked. Also I can hear what I assume to be the fuel pump humming quite loudly but it goes away after I get about a mile down the road. I just don't know where to go next. I feel like I can't even afford to drive it the way it drinks up gas. Does anyone have any insight as to what else this can be.

[nos4blood70]

Are you losing coolant?

[MrJiggy716]

Carl can you explain the loss of coolant affecting MPG just out of curiosity?

[crash93ssei]

Any chance the firing order is not right?

[MurderMitten]

I had similar symptoms with my malibu. It's very uncommon but is possible, my problem was I broke a head stud. Just pop the valve covers off and see if everything is how it should be

[Realtree11]

Coolant is all good, I'm planning on just changing all my injectors to see if that helps. And now a new problem is my AC bearing starts whining when I turn too sharp. It's just one thing after another with this car.

[95se]

Check and make sure the firing order isnt screwed up, if that doesnt solve it a shop can check with a scanner to see what the injectors are doing.

[Realtree11]

How would I go about checking the firing order? Would I need any type of special tools?

[crash93ssei]

Check this thread for firing order http://www.pontiacbonnevilleclub.com/fo ... er#p292154

[swampthing]

Does the car heat up to normal operating temperature 195°?

[gweg_b]

Could be ICM causing the misfires. I fought with this for 2 years until I found out the ICM was the culprit.

[Realtree11]

Firing order is correct, car is at optimal temperature. I just filled it up and I'm down to 7 mpg. I have been meaning to change the fuel filter which has never been changed is it possible that the fuel filter is all gunked up and causing problems? And when I start it it smells like straight gas.

[SuperHbody]

Could be but if your smelling gas I'd say you have a severe leaky injector or it could be the fuel pressue regulator on the fritz.

[crash93ssei]

I would go and do a very thorough check of the fuel lines for rust and wet spots as well as paying close attention to all connection points. Sometimes they have been known to leak at the connections to the fuel rail. Other then that a stuck open injector could play hell with the way it runs.

[Realtree11]

Ran a code on it and it's got random misfires. So I already changed plugs, plug wires, coil packs. What else can cause a misfire?

[mrwildroot]

ICM- ignition Control Module

[crash93ssei]

Give this a try and let us know what you find http://www.pontiacbonnevilleclub.com/fo ... 42167.html

[RJolly87]

I would check the fuel pressure regulator to ensure it has not failed

[quicksilver]

See if you could swap your icm with a known good one to see if that helps. If your fuel filter is really old, then I would replace that regardless.

[vogie01]

I would check the fuel pressure regulator to ensure it has not failed

I would have to agree. Check the FPR first and MAF. Sounds like it might be both. If those test out good then continue with the basics such as O2 sensors and what not. Jumping to coils and ICM might take you in the wrong direction. Recommend changing the fuel filter for good measure if you have not done it yet. The fuel smells screams FPR and the shaking says MAF to me.