Question : sluggish 2001 Century shortly after new fuel pump

[toot77]

My wife’s 2001 Century 3.1, 120K miles, has suddenly developed a sluggish problem that has me perplexed. Here is some history; The only service issue with the car since new, was an intake gasket leak at about 75K miles. At that time, along with replacing the intake gasket, I replaced spark plugs, wires, all hoses, thermostat, water pump, and flushed the coolant system. Car has been fine until a couple months ago. The fuel level gauge started acting erratically. I decided to replace the entire fuel pump rather than just the level sensor due to the age and miles.

So here is the problem; I installed a new fuel pump, new fuel filter, and while I was at it, I replaced the air filter. Everything was okay for a week, then suddenly the car lost power and became very sluggish. It never quit, but it is difficult to get above 40mph. The CEL has not come on. (I have an Innova 3130 scan tool and no faults have been reported.) The engine starts fine, and does not run too bad until it gets warmed up. Once I am a mile down the road, it bogs whenever the gas pedal is pushed especially if going up any kind of grade.

After convincing myself that it had to be fuel related, and because I had just replaced the pump, I got another and replaced it again (same name brand pump as I first installed). No change. I also replaced the fuel filter for a second time. I have visually inspected connections and all appears okay. I cannot detect the sound of any vacuum leak. Still no cel codes. I suspected the MAF because it is in the plastic air duct that must be removed to change the air filter, but everything looks okay.

Any suggestions would be appreciated. My Innova Equis 3130 has live data but I do not know what acceptable reading are in order to diagnose MAF or other things that do not throw codes.

Please help.

Thanks
dw

[Fireball]

My wife’s 2001 Century 3.1, 120K miles, has suddenly developed a sluggish problem that has me perplexed. Here is some history; The only service issue with the car since new, was an intake gasket leak at about 75K miles. At that time, along with replacing the intake gasket, I replaced spark plugs, wires, all hoses, thermostat, water pump, and flushed the coolant system. Car has been fine until a couple months ago. The fuel level gauge started acting erratically. I decided to replace the entire fuel pump rather than just the level sensor due to the age and miles.

So here is the problem; I installed a new fuel pump, new fuel filter, and while I was at it, I replaced the air filter. Everything was okay for a week, then suddenly the car lost power and became very sluggish. It never quit, but it is difficult to get above 40mph. The CEL has not come on. (I have an Innova 3130 scan tool and no faults have been reported.) The engine starts fine, and does not run too bad until it gets warmed up. Once I am a mile down the road, it bogs whenever the gas pedal is pushed especially if going up any kind of grade.

After convincing myself that it had to be fuel related, and because I had just replaced the pump, I got another and replaced it again (same name brand pump as I first installed). No change. I also replaced the fuel filter for a second time. I have visually inspected connections and all appears okay. I cannot detect the sound of any vacuum leak. Still no cel codes. I suspected the MAF because it is in the plastic air duct that must be removed to change the air filter, but everything looks okay.

Any suggestions would be appreciated. My Innova Equis 3130 has live data but I do not know what acceptable reading are in order to diagnose MAF or other things that do not throw codes.

Please help.

Thanks
dw

I'm no expert but this possibly sounds like the CAT going bad?

[bszopi]

Check for spark on your plugs. My thought is coils. If you find plugs that aren't firing, see if they are on the same coil. If so, swap around the coils and see if the no-spark follows the coil.

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[MidnightriderZ24]

I'm no expert but this possibly sounds like the CAT going bad?

w bodies are known for plugging converters. unbolt the downpipe bolts, pull it off the studs and go for a drive to see if the power is there

[toot77]

Thanks for the replies. I have a little more information. It is still sluggish, it does start and idle fine. Once up to speed it does seem to run along just fine up to about 45 mph, especially if on a slight down hill grade. During all this, it does not seem to have any miss at all. Should I still suspect a spark issue in this case? But, as soon as it hits an uphill grade, or if you try to accelerate, it really falls flat on its face. To me the first sensation is almost the same as if it is running out of gas. I did learn yesterday that if i floor the gas pedal, it will down shift and rev up, but obviously with a lack of power, it will accelerate slowly, and will never shift back up as long as the pedal is floored. It will get up to about 60mph doing this. and I guess the engine to be running 3500 rpm range. At that point, it will start popping out the exhaust and continue as long as pedal is held to the floor (at least for the 2 or 3 seconds that I held it there). If this is a plugged cat issue, would it have appeared so rapidly? This all started overnight, there was no build up to it. I am still hung on the fact that it all started soon after the fuel pump & air filter change so I have a hard time not thinking that it is related to one of those.

Would either a spark/coil issue, or a cat issue, throw a cel code?

Thanks again
dw

[toot77]

Well, it appears that the cat is the problem.

What is a good cat to buy? I have heard stories (from people wanting to sell you something costly) that the lesser cost aftermarket cats do not have enough volume and will more likely throw O2 sensor codes. Anything to this?

thanks

[pocket-rocket]

I bought a Walker universal cat for my pickup for $45+ tax at Advance auto and it works just fine. Mine doesn't have a rear o2 but the exhaust smells just like any newer cat does to me so I imagine there would be no codes set. Besides it had to meet emission standards so it had to be fine.

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