Thread: fouled plug on #3 cylinder

OK guys new to the forum. I have a question. I have a 1995 Grand Prix SE 3.1 and my #3 plug keeps fouling out. I have replaced the coil pack and wires. I did a compressions test on all cylinders and they all read 160psi. The only other thing I can think of is the fuel injector. But those rarely go out anymore on any car. Any ideas would be greatly appreciated. Oh also has a miss in the engine which I am guessing is from the fouled plug.

So do you think I should change that injector or is there anything I can do to try and free it up.

Sounds like you hit the basics. It's tough to figure out another cause. After you change the plug, does the car run strange (such as a mis-fire)?
I have a '94 Grand Am with the 3100 and I've had an injector fail on it before (had the same position fail 1.5 years later, both times I replaced with a brand new injector). I don't remember exactly what my symptoms were, but I know it had a noticable performance problem (I think it was doing a lot of stumbling and idled funky, but don't hold me to that).
The injectors are simple to change, it takes me about an hour to do it (and that's not being rushed, just slowly taking my time).
If you do it, replace the o-rings on any injector you pull out of the intake! I know people that tried to cheap-it and not replace the o-rings and later had to rip it all apart again.

Originally Posted by TLSheff

If you think it really is the injector, swap cyl#3 and #1 injectors, give it a bit and see if #1 fouls, it so... replace injector, if 3 fouls its something else

That takes time and again, I'd want to replace o-rings on injectors. If you're going to spend the hour to do that on the 3100, just replace the injector and see if it corrects the problem. Not worth ripping it apart twice.

Some people ohm test injectors, but the 3100 does not give easy access to the injector plugs without removing the upper intake (again, might as well replace it).

But I was wondering if there are other symptoms that may help confirm an injector OR point to another issue.

injectors are $80+

orings are $2

What is at most an hour of your time worth to you?

Is it worth $80?

Most people dont make $80 an hour lol

Originally Posted by matt5112

injectors are $80+

orings are $2

What is at most an hour of your time worth to you?

Is it worth $80?

Most people dont make $80 an hour lol

I don't make $80 an hour (nor do I know anyone who does), but if you have to do it twice (once to move it and then again to change it), it's 2 hours. I don't know about the OP, but I have to work outside and right now IT'S COLD! I don't wanna do anything I don't have to for long in the cold.

I'd rather find steps to confirm it's worth the hour and the $80 ahead of time, that's all. Granted, he's changed the coil (which I would have rotated the coil, that's like 5 minutes no big deal), he changed the wires and did a compression test. I am assuming that each time the plug fouls he's putting a new one in and not just cleaning the fouled plug and dropping it in, so it is all pointing at the injector as the next logical thing. If he is cleaning the fouled plug, this could be a case of bad plug.

That raises another question. The plugs in the car, are they all AC Delco? If no, I'd swap them all to shiny new AC Delco's. Stay away from BOSCH plugs. Personal experience and opinion, BOSCH plugs are crap in GMs (and you won't get the right life out of the plug).

thanks guys for the info. Yes it is sputtering. I cant think of anything else it could be other than the fuel injector. I am just going to change it and get it over with. If that's not the problem then I will have a Blue 95 Grand Prix SE for sale. With ONLY 56,000 miles. Yes that's right only 56,000 miles. LOL.

Originally Posted by Langdon

thanks guys for the info. Yes it is sputtering. I cant think of anything else it could be other than the fuel injector. I am just going to change it and get it over with. If that's not the problem then I will have a Blue 95 Grand Prix SE for sale. With ONLY 56,000 miles. Yes that's right only 56,000 miles. LOL.

Make sure to update us and share if that solved it. I've got a strong feeling that will be the fix!

ok guys fixed the problem. Just ran a can of sea foam through it and within about 50 miles it ran awesome. I went to get a fuel injector and the guy at the auto parts store said run this stuff through it first to see if it fixes it. $8.95 a can and about $5 in gas and it is fixed. No more plug fouling out or spuddering.(spelling) anyway the guy says that the stuff can cure a lot of fuel problems. Also said to try and run it through about once a year. Thanks guys for all the input.

Originally Posted by Langdon

ok guys fixed the problem. Just ran a can of sea foam through it and within about 50 miles it ran awesome. I went to get a fuel injector and the guy at the auto parts store said run this stuff through it first to see if it fixes it. $8.95 a can and about $5 in gas and it is fixed. No more plug fouling out or spuddering.(spelling) anyway the guy says that the stuff can cure a lot of fuel problems. Also said to try and run it through about once a year. Thanks guys for all the input.

Interesting and good to know. I have never had luck with injector cleaners (never tried SeaFoam). Thanks for the update!