Ive posted a few times here lately and haven't got responses and cant find it in the forums! So im going to try again! My truck started spitting and sputtering down the road and finally cut off. It wont do anything but turn now! Ive just recently replaced the ignition control module,which was the same symptoms im having now,so i started there but it wasnt the culprit this time! Ive flashed the computer but its not putting out a code so im now leaning toward fire since the injectors are shooting fine. Im going to check the coil and distributor tomorrow. My main question is would a sensor go bad to the point the vehicle no longer runs with out storing a code? Such as the cam or throttle position sensor or even the egr or map sensor? Its a 1989 4.3 tbi and everything but the coil has been replaced with in an oil change!

 

An 89 is Pre- OBDII so yeah I believe it can have a sensor issue and not throw a certain code. Have you checked for spark? How do you know the injectors are firing? Do a fuel pressure test and leak down test to see if there is a problem with the injection unit or fuel pressure regulator. I see you have a TBI unit so this could be a fuel pump pressure issue and it may be starting to give up the ghost.

 

Im going to check for spark tomorrow,being its thanksgiving harbor freight was closed and they seem to be the only one in my area that sales a spark plug tester! When it went out i had my dad turn the ignition and i could see the injectors working and spraying properly. I can also smell the gas while i was installung the new ignition module. Im hoping its the coil because everything else related to fuel or fire is brand new! I know according to the flash code sheet that all the sensors should at least store a code and the check engine light came on when it started to act up! But it doesnt flash anything! I mean it was running fine and then it started sputtering for a few miles then right before it cut off it backfired extremely loud! Which is what it did with the module! If its not the coil and the fuel pressure is fine what would be your first guess?

 

I agree with Gregg64 that you should do a fuel pressure leak down test as part of your diagnosis. It should show 60-66psi at the test port with the ignition on and engine off, and then should hold above 55psi for at least 10 minutes after you turn the key off. Anything less than this will cause a no-start situation. These trucks are very sensitive to fuel pressure variances.

 

I mean ive had multiple problems with fuel pumps in my 20 years of driving s10! But would i be getting fuel to the injectors and the injectors spraying normal with anything less than 60psi? I still havent checked the fire on it but ive noticed since i replaced the ignition control module that when i go to get on it and accelerate fast it stutters,like it doesnt react for a second,then goes. Its done it twice,and the second time is when it started sputtering and finally went out. And thats where im currently at due to the holidays and work i haven't been able to look at it. Just trying to get a general idea on where to start so i dont throw money away. I naturally started with the ignition control because it was warrantied and it wasn't the problem

 

Those certainly could be symptoms of a leaky/weak fuel delivery system. Do the leak down test and post up your numbers.

 

89 TBI Fuel Pressure should be around 11 PSI. There is no built in test port for the TBI. I have an 89 TBI that I have had since new and now has 430K miles. If you have spark than I would check the temp sensor for the computer. One by the water inlet. Running rough could aslo be an injector. The last time that mine was running rough it was the injectors. I do not believe there is a CAM sensor on the 89. The O2 sensor controls open/closed loop operation. If the timing chain jumped you will crank and crank and crank. You could try loosening the distributer hold down bolt and rotating the distributer a little bit each way to see if it fires. It comes down to Fuel, Spark and Timing.

 

Well I knew the computer could be an issue and i know about the o2 sensor but i didnt know about the temp sensor. Ill sure check it. The injectors are firing fine though. Does the 89 have the self afjusted timing i keep hearing about?

 

There is an electronic advance wire. To set the timing with the timing light to spec. You disconnect the advance wire. It is a tan or brown wire behind the carpet on the passenger side that had a connector you unplug. The wire is just behind the top edge of the carpet underneath the dash. There are two temp sensors one if the dash gage/light and one is for the ECM. The one for the dash is on the passenger side of the engine.

 

Well the one for the dash on mine is on the thermostat i believe but where is the one for the ecm?