This is'nt for a 3rd gen it's for a 90 fullsize JImmy.I'm asking here because people here seem to know more about tbi than people on the blazer forum since most of them are running carbs.I have a 350 tbi thats been running rough for about a week.I checked with a scanner and got a code 43.According to my code book a 43 is either a knock sensor or throttle position sensor both of which i changed and still have the same problem.The instructions that came with the tps said it needs to be adjusted after installation but my haynes manual says the tps is'nt adjustable.Does anyone know if it is or not?

 

It all depends if replacement TPS has a slot instead of hole for one of it mounting holes. IFRC 1990 should have non adjustable TPS, but I could be wrong. You can check TPS voltages by verifying Pin B - Blue wire voltage vs. ground:

at idle it should be between 0.25 and 0.85 volts (ideal 0.55)
at WOT it should be above 4.25 Vdc

This can be done with engine off - ignition key in run position.

Scanner should report 0% TPS at idle and 100% at WOT


//RF

 

The replacement tps has 2 holes for mounting.According to the istructions that came with the tps i need a special adjustment tool part#j-29607,but when i do a search on the napa website which is where i bought the tps nothing comes up.

 

The j tool is next to impossible to find and you really do not needed. Just get yourself a cheap DVM and measure the two voltages as outlined above at two throttle positions. If you have the two voltages within range - you are good to go.

//RF