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2001 Sunfire Engine Shuddering
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DanieP80
New User
Jun 7, 2007, 5:40 PM
Post #1 of 5
(2017 views)
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2001 Sunfire Engine Shuddering
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I have a 2001 Pontiac Sunfire. It's an automatic with a 2.2L engine. It's been a pretty reliable car for the last five years and 115,000m(I bought it used with 16,000m in 2002). I had to have the fuel pump replaced about 6 months after I bought it, but nothing other than wear and tear since then...until a few weeks ago.
Now, anytime I have less than 3/4 tank of gas and have spent any time driving (and I have a 40m commute to work), the engine starts to shudder anytime I am stopped at a light or stop sign. It also acts up when I am going up a hill or accelerating after stop and go traffic. It feels like it doesn't want to change gears. It hasn't stalled out on me yet, but I'm getting more and more afraid it will.
I took it into the shop last week. The mechanic changed the transmission fluid and filter, the fuel filter, and cleaned the throttle. He also "Sea Foamed" the intake and outtake (I think that's right...I am not up on all the lingo.) He said that after doing all of this, he drove it and couldn't get it to act up. However, the car had almost a full tank of gas at the time, and he didn't drive in the conditions I'm used to driving. I was hopeful that it was fixed, but I've learned that it still acts up if I have 3/4 of a tank or less.
I'm really at a loss here. I don't know if it's electrical, transmission related, or engine related. With my luck, it's all three. If anyone can offer some suggestions, I would be truly grateful. Thanks in advance.
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DanD
Veteran
/ Moderator
Jun 8, 2007, 4:54 AM
Post #2 of 5
(2013 views)
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Re: 2001 Sunfire Engine Shuddering
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I’m not saying it can be anything to do with the fuel level in the tank but I think it would be a first. The fuel pump is situated at the bottom of the tank and as long as there’s enough fuel to cover the pump, in theory it’s going to pump that fuel.
That being said this trade never ceases to amaze me. LOL
I would start attacking this problem with all of the basics, ie tune-up; as in spark plugs, ignition wires testing coils. If after that the problem persists begin looking at electronics, having the computer scanned. Not so much for trouble codes because you didn’t mention a check engine light but looking at sensor inputs and computer outputs to the individual devices.
Just sitting here thinking about this and the only thing I can come up with that may have something to do with the fuel level in the tank is the EVAP (evaporative emissions) system? If the vent valve is stuck closed not allowing air into the tank; the fuel pump may be is creating such a high vacuum in the tank that it cannot pump fuel at the proper pressure or volume. But then again the fuel cap check valve would also have to be stuck shut; I don’t know, just thinking out loud and like I said this trade never ceases to amaze me.
Dan.
Canadian "EH"
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 8, 2007, 6:20 AM
Post #3 of 5
(2010 views)
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Re: 2001 Sunfire Engine Shuddering
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DanD - I think you got it, no surprise. The common denominator of this problem is that the gas cap had been recently removed when it runs well - ding, ding, ding, you won!!!! It didn't act up for the mechanics because they probably put some SeaFoam in the gas tank which relieved the vacuum that was overcoming the fuel pump.
DanieP80 - Try opening the gas cap and put it back on when it does this. If you notice a change you know this is holding too much vacuum and you might even hear it but with the screw type gas caps you might not. If this is happening leave that cap a little loose as if the tank gets lower it could implode the tank. Get a new cap to rule that out -- it could have been mixed up at a gas station maybe???? Make sure you have the exact right gas cap. If that fixes it that was it. If not the evaporative side may be restricted or the fuel pump can't even overcome normal vacuum which is slight in the tank.
Never hurts to do tune-up stuff if it's been a while either,
T
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DanieP80
New User
Jun 8, 2007, 6:49 AM
Post #4 of 5
(2007 views)
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Re: 2001 Sunfire Engine Shuddering
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Thanks for all of the advice guys. I had to buy a new gas cap not too long ago (around the time this all started) due to the fact that someone took my original cap. I purchased the one that Advance Auto said would fit my car, and I thought all would be well. Guess not.
I have noticed that the new cap is hard to get off at times, so everything you said makes sense.
Would this also explain the loss of horsepower?
Thanks again! I'll get that taken care of...an imploded gas tank sounds none too pleasant.
(This post was edited by DanieP80 on Jun 8, 2007, 8:35 AM)
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DanieP80
New User
Jun 10, 2007, 7:21 PM
Post #5 of 5
(1993 views)
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Re: 2001 Sunfire Engine Shuddering (update)
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Well, I went to the Pontiac dealer and bought the gas cap that is supposed to be on the vehicle. However, my poor car is still acting up.
I'm taking it back to the shop to get the EVAP system looked at, but I have another question.
I was driving the other day and the low coolant light came on for a second and then went off. I was driving up a small hill at the time,and had been driving for over an hour. Should I just get the coolant level checked? The car doesn't over heat, since the gauge stays around its normal 195 degree mark.
I'm really starting to think it's time to invest in a Toyota.
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