Not a FSC but its a Chevy

[1997chevydriver]

hey guys my dad has a 98 S10 2wd with the 4.3l vortec in it and he is having issues with it. I know the first rule to diagnoseing a problem is DO NOT just throw parts at it but my dad doesnt apparently know that perticular rule:eyecrzy:..... Anyways the problem he is having is at idle there is a random misfire that you can feel but it comes and goes. if ya rev it up most of the time it goes away but othertimes it gets worse. When you put it in gear and hold foot on brake and try to do a break stand but without letting tires spin the miss seems to get alot worse. He has gotten the code for cyl 5 misfire and random misfire codes. he is almost ready to part out the truck cause he cant fix it. he has replaced the timing chain and gears, cap, rotor, plugs and wires with new. he has swapped coil, ign module, crank position sensor with ones from a working blazer with no change. he put in a used distributor and spyder injection system with ones from a junkyard (vehicle was rolled so in theory they should be good). Sorry for the novel, any help would be greatly appreciated(sp?)

[Mr_Shamrock]

I would do a compression check. I had a 2000 S-10 that was doing the same thing and having replaced a spider injection in one before and curing the problem I couldn't see past that. I quickly learned that a little testing can prevent your wallet from losing a lot of weight. My truck ended up having two low cylinders so it got sold to a mechanic after I dumped about $300 in it.

[1997chevydriver]

ok ill have my dad do that he said he checked 3 of the cyls and they were around 150 i guess he couldnt get to he other 3 so idk

[SlvrdoHDmax]

Has it been loosing any coolant? Intake gaskets can do that..

[1997chevydriver]

nope antifreeze levels havnt moved exept when he did timing chain

[wild willy]

Is this one of the years that had that spider fuel supply inside the intake manifold? They were famous for being leaky and a real pain to fix. Random misfire could be electrical or fuel problems. Check the high tension electric, plugs, wires to make sure everything there is 100%. Have you replaced the fuel filter any time recently? Check the fuel pressure?

[1997chevydriver]

if you read everything in the first post 95% of what you just asked has been checked/ replaced/swapped with known working ones. fuel filter has been replaced but pressure has not been checked. he doesnt want to buy a gauge and cant drive it to town to have it checked because of how horrible it runs.......

[wild willy]

Well, thanks for the thoughtful, well-reasoned reply- I did ask a question, and you answered it. If you daddy can replace the "the timing chain and gears, cap, rotor, plugs and wires with new. he has swapped coil, ign module, crank position sensor with ones from a working blazer with no change. he put in a used distributor and spyder injection system with ones from a junkyard (vehicle was rolled so in theory they should be good) maybe he can afford a used fuel pressure guage, too, or at least borrow one. Maybe he can get that from a junkyard, too, so he can be sure that it is "theoretically" good. Sorry I tried to help, I will know better next time....

[1997chevydriver]

sorry about that didnt mean to come across like an a$$ but my dad is one of those people i guess that like to throw parts at sh**. yesterday he Finally decided to stop throwing parts at it and we parked it outside. i think he gave up and is getting ready to part out / scrap it. Also none of or neighbors have a fuel pressure guage.

like i said sorry for sounding like an a$$ didnt mean it.

hope i didnt turn any other suggestions away by my horribly worded post............sorry everyone.......

[wild willy]

Yes, I don't mean to be a jerk, either. I had missed the spyder comment earlier, and I have a '97 Blazer, so was sharing my experiences with you. If you are having issues with a miss, especially under load, doing brake stands, the volume, as well as the pressure of the fuel pump should be looked at. Sometimes a pump can have good pressure, but not move enough fuel to support good power from the engine- I don't think a fuel pressure gauge is that expensive, and any excuse to buy new tools is a good thing!

[1997chevydriver]

true....ill see if i can talk him into it but he also thinks low fuel pressure will only cause a bog not a heavy miss but telling him other wise is like talking to a wall sadly. i have already mentioned fuel pump/pressure before to him but he went back to saying it wont cause a miss just a bog.......


Edit: Also i forgot to add that last summer when all this crap started the exhaust smelled strongly of sulfur. Doesnt that mean that raw fuel is getting into the cat??

[wild willy]

If you saw my PM, I mentioned that I had a similar experience years ago with a Toyota that had a clogged catalytic converter. Took a while to figure that out, I replaced the fuel filter and fuel pump first. Luckily, I had a parts car, where I eventually got the catalyst from, too. Really felt like a fuel problem, wouldn't run under load at full throttle for more than a few seconds, felt like it was running out of gas. Try testing the truck with the exhaust system disconnected.

[1997chevydriver]

ya i got it just added that raw fuel part so everyone else can see it too. and ill have to try that whenever it ends up back in the garage again or when the ground decides to not me a mud pit.....