89 4.3 questions

About 3 months ago I bought my 89 S10 as a work truck. I really like this truck and now I want to fix it up a bit (my wife thinks I'm crazy). I've noticed a few things/issues with it and was wondering if anyone might know what to check for. BTW, it's a 4.3 automatic with AC, about 95K miles and doesn't look like it was well maintained since it was this other guys work truck. Anyway, here goes.
1) Sometimes it runs really great, lot of power, etc. Other times, it seems to surge/hesitate throughout the driving range and poor idle. At idle, It'll stumble, something under the hood 'clicks' and the idle picks up then after a bit it 'clicks' again and back to the stumble. I've changed the plugs, rotor, dist cap, wires and air filter but haven't done the fuel filter yet.
2) After driving for about an hour or so, I noticed water from the AC unit dripping. It's clear so I know it's not the cooling system. Condensation? But why, the AC is not turned on. This may be related but after restarting, the windows begin to fog up near the dash vents without the fan on.
3) Is it possible to install speakers in the door vents? If so, what size? I haven't pulled the door panels yet to have a look.

Any help or advice is GREATLY appreciated. This is a fantastic site!

The first thing that I like to change on fuel injected auto's is the fuel filter, just because most people don't change them often enough which kills the fuel filter (very expensive job to replace) Anf a full tune up will probably fix your motor problems.

Most auto's with air conditioning use the air to defrost the windows, which is probably why your AC unit is dripping. If you can just turn the heat (or vents) on and leave the defrost off and see if the system still drips then.

Your door vents are there to help the doors close, and to help any moisture dry, so you really shouldn't plug them up with speakers.
Any welder will probably plasma cut speaker holes into your doors for a very low price. It's only a 10 in job if you pull the door panel for them, and mark the holes oul

Oh that's kills the fuel pump, which requires you to either raise the box, or lower the fuel tank.

the clicking noise you hear is the ac unit. it does come on when you use your heat. i bet when you change your fuel filter it might clear up a bit. if your old fuel filter seems really full of crap, after you put the new one on check you fuel pressure to be sure you pump is fine.
if you have a tbi pressure should be 9 to 14 psi.
hope that helps.

the clicking noise you hear is the ac unit. it does come on when you use your heat. i bet when you change your fuel filter it might clear up a bit. if your old fuel filter seems really full of crap, after you put the new one on check you fuel pressure to be sure you pump is fine.
if you have a tbi pressure should be 9 to 14 psi.
hope that helps.

On an '89, the AC will only run in the Defrost mode, not the heat or on the vent position.

you sure my 91 does?

you sure my 91 does?

If your '91 has the same heater controller on the right side of the instrument panel as a '94, '93', '92, '90, '89, etc.. The A/C should run in the A/C, Bi-level, Max and defrost positions. It should not run in the vent or heat positions.

the clicking noise you hear is the ac unit. it does come on when you use your heat. i bet when you change your fuel filter it might clear up a bit. if your old fuel filter seems really full of crap, after you put the new one on check you fuel pressure to be sure you pump is fine.
if you have a tbi pressure should be 9 to 14 psi.
hope that helps.

A serious question. How will changing the fuel filter clear up an A/C problem? Am I reading your answer wrongly?

A serious question. How will changing the fuel filter clear up an A/C problem? Am I reading your answer wrongly?

No changing the fuel filter won't correct a air conditioning problem but it will help your truck run better, plus help save your fuel pump.

I don't think that there is any thing wrong with your air conditioning, except it might need a good service in the spring. To me it sounds It's acting normal.

youre right my ac doesnt come on in those positions, just used to running defrost all the time and i got confused. lol
yes you read it wrong, i should of started a new paragraph when i started on the fuel filter.
sorry about the ac thing. and i promise never to have run on sentences ever again. lol

S10newbie: If you are noticing the power loss problem, related to the click noise, with AC or Defrost on then the most you can do is have the compressor and AC system looked at. If this problem is occuring with the heat/vent on or when nothing is turned on then you have a problem. That means your compressor is turning on when it isn't supposed to. In this case something in the electrical is shorted out and should be diagnosed. Good luck.

No changing the fuel filter won't correct a air conditioning problem but it will help your truck run better, plus help save your fuel pump.

I don't think that there is any thing wrong with your air conditioning, except it might need a good service in the spring. To me it sounds It's acting normal.

UH,,, Overboard, I didn't ask the original question and was only asking jackass#1 what his reasonning was for changing the fuel filter for an A/C problem which he has answered.

s10newbie, are you there? could you reply to any of this? hows it going?

s10newbie, are you there? could you reply to any of this? hows it going?

Yeah, I'm still here. Just been working a lot of 10-12 hour days this week and I haven't had the energy to 'play' around with the truck.

Regarding the AC clicking, I do run the defrost mode most of the time but I'll try and mess around with the controls and see what happens.

Hopefully, I can 'play' this weekend a little bit. I'm planning on changing the fuel and air filters, PVC valve (seems OK, but cheap to replace) and was thinking of checking/cleaning the EGR since I've seen other threads mention this. Thanks all for the suggestions. I'll update when I have something.

yeah the egr is a common problem. as for the water dripping from ac unit, its normal if the ac unit is in operation. as mentioned earlier ac unit does come on
when you use your defrost.
let us know how things go.

yeah the egr is a common problem. as for the water dripping from ac unit, its normal if the ac unit is in operation. as mentioned earlier ac unit does come on
when you use your defrost.
let us know how things go.


Ok. I changed the fuel filter, PCV valve, air filter and changed the oil. BIG difference. Now have some power. There still seems to be some hesitation/stumble when I keep the pedal steady especially when cruising around 40mph or so. It's at a relatively low RPM and sometimes idle. (I don't have a tach) But I really don't notice it when I'm driving in the 60-70 range. It seems fine on acceleration.

I haven't tried cleaning the EGR or checked the timing (???) yet but do you think I might still have some junk in the injection system since the filter was obviously bad? What kind of additive should I use to clean it?

Thanks much...

PS. The AC does come on in the defrost position and I think maybe the Heat position too. In the Off postion it does not. Gotta play with it some more to see.... I still don't understand why it turns on in the defrost position though....

Ok. I changed the fuel filter, PCV valve, air filter and changed the oil. BIG difference. Now have some power. There still seems to be some hesitation/stumble when I keep the pedal steady especially when cruising around 40mph or so. It's at a relatively low RPM and sometimes idle. (I don't have a tach) But I really don't notice it when I'm driving in the 60-70 range. It seems fine on acceleration.

I haven't tried cleaning the EGR or checked the timing (???) yet but do you think I might still have some junk in the injection system since the filter was obviously bad? What kind of additive should I use to clean it?

Thanks much...

PS. The AC does come on in the defrost position and I think maybe the Heat position too. In the Off postion it does not. Gotta play with it some more to see.... I still don't understand why it turns on in the defrost position though....

Glad to hear it is a little better. The A/C cones on in the defrost position to dehumidify the air blowing on your windshield. It will not be on in the heat or vent positions.

Since the previous owner neglected this ole gal, perhaps a good throttle body cleaning would help. It will improve your idle and throttle response.

Clean the throttle body, eh? Can you maybe give me a quick rundown on that. Most of my repair experience has been in the carburator and points era (toredown and rebuilt a 70 Chevelle SS). I think you mean to remove the fuel injector and clean it. Can you maybe a little more specific. I do have a Haynes repair book but I think a Chiltons would be better and more detailed.

go to parts and get throttle body seal kit ($6.00). in
the kit are all the seals and gaskets you will need plus
a step by step with pictures. atleast the one i got from autozone did.
its alot easier than a carb.

Go ahead and just try this... Get some throttle body cleaner and with the truck a little warm (not running temp but not ice cold) spray some down in there. Then take a clean cloth and spray some on it to wipe down everything metal you can. Take off the IAC and spray it with the cleaner along with the hole it goes into, making sure everything is clean. Let it sit for a minute and start-r-up, it will be hard to start but thats normal. Then spray more down in there with it running, but only in sperts so as not to hurt your cat. This should help your idle out a lot.

^ What he said.