Hi like many Before me I have a k-1500 1989 Chevy pickup 4x4 5.7 350 And also like many before meHave a problem with It running extremely rough gone through everything fuel filters, fuel pump, Dist

Possible fuel injection spider on top of engine. It has 8 lines that puts fuel into each cylinder.1 or more can go bad at a time not putting enough fuel to the cylinder causing a miss, rough idle

Its a throttle body 2 injectors. that's it & they were recently repaired temp & map sensors also replaced only things I haven't tried are counterparts or electronic components. aside from the temp & map sensors . its definitely missing like running on 3 to 4 cyl.s thought maybe valve issue. it got so bad I even tried just reving it to blow it out . All that acomplished was blowing out my brand new exhaust doughnut gasket. now I have an exhaust leak to boot . >:(

I'm at my wits end my wife wants to divorice me over this crap. So far I've put upwards of $13,000.00 Into this $2000.00 vehicle. I can't turn back now there's no way I'll ever get even close to what I've put into it. so as you can see I really need to get thus

Sry . this figured out.

My bad I thought it was 98 not 89

Unless you know someone that wants to buy a 25 yr. Old money pit for $14,000.00. :)

I wish

Check compression if good then try a pcm?

It was a great truck until I started getting it repaired. but the trans started slipping so I had the rear seal redone along with the filter. That's when I found out the WHOLE front end needed to be replaced, which I did. 1st $5,000.00 along with complete new exhaust ( cat conv., flomaster muff to dual streights out the back all new brks & tires .just in time for the trans to completely take a crap .yup you guessed it . new trans . another $5,000.00

Pcm ?

Valve of sorts I'm guessing

Well if anything everyone will get a kick out of the idiot that rebuilt a giant dog t*@d. |:(

Thanks for input .so for all you puzzle solvers out there this one's for you. :) good luck

Yes.The PCM may not sending a ground signal to fire all cylinders

It may be intermittently dropping out.

Sorry about your luck. The highest failure item I've had on my '92 (same TBI setup) is the ICM (Ignition control module) in the distributor. I'm on #5 and it is know the first thing that I change. There is also a pick-up coil in the distributor that is wired to the ICM (changed once). The ICM reads engine rotation from the pick-up coil coverts it and sends the signal to the ECU (Engine control module (PCM is powertrain control module is the newer version were it controls the tranny as well as the motor). The ECU then controls the engine using this input and the input from the other sensors. It also sends the spark advance signal back to the ICM for proper timing. Figured I'd go in depth there to try and help you. If you haven't changed the ICM try it (I carry a spare, NOT KIDDING). Also have you verified your engine timing and firing order. We have 8 of these TBI's and haven't had a ECM failure but there is always a chance. When you/they worked on the throttle body was the regulator looked at (in the back) fuel pressure checked? Well get started with that info and let me know. Sounds like big issues so it will be easier to check a few at a time then move on. The ICM should be under 60. Ensure you apply grease between the new module and the base of the dist or you'll be doing it again shortly (been there). The grease should be provided if not a good di-electric works.

I had the same problem and as soon as I put a 40dollar airtech fuelpump in no more problems. I have a g20 van1989 with 5.7 engine. It was easyto chanchange. It looked like I had good fuel to fuel injectors but now I know looks are deceiving. Hope this helps.

Did you ever get an answer for this? I am going through a similar issue with my truck.