This car (91 Z28 350 TPI L98 700r 4)as been sitting awhile (2 years or so) it started and ran but needed a thermostat because it wouldn't warm up to operating temp. SES light was set so I checked it and it gave a code 15...Coolant temp sensor. Assuming it was from not warming up properly I cleared the code after installing the thermostat and started the car. It ran rough for the first few seconds and when idled smoothly for 5-10 minutes or so....then it changed tone and started to load up(could smell the gas). I tried to hit the throttle to clear it out and it stalled. Would not fire again. Cranks good....but nothing and there is a strong smell of gas. I had to remove the Throttle Body to replace the thermostat and cleaned it good with carb cleaner...which in my ignorance I also sprayed down the TPS a no no I guess. so I checked the TPS and it read .70 v at idle. could not adjust it down to .54 where it is supossed to be ...would this cause it to not start? Any other suggestions?

TIA

 

sounds like you were running way rich, since the new coolant temperature sensor might have been grounded on something, or you didnt install it correctly (you always have to doubt your own work until you've checked it over several times)... it also sounds like you were trying to run the car on 2 year old gas. This is going to be another of your problems.

You'll need to either take a propane torch to the spark plugs to refurbish them, or just go to a auto parts store and get new spark plugs since the ones you have in the car now are fuel fouled, thus why it wont start anymore.

 

Why would you refurbish a spark plug?

Sounds to me like it's flooded. Replace the plugs. Try starting it with your foot on the loud pedal. Might want to replace the CTS, too.

 

Didn't replace the coolant sensor just cleared the code from the computer. Have a spare TPS from another system I have I will try it and see what happens. Whats the CTS and what does it do?

TIA

 

(CTS = coolant temp sensor) tells the ecm the temp. of the coolant

 

CTS coolant temp sensor still wondering why it ran as long as it did before a problem showed up...well just have to do a little more diggen I guess

 

No man... your CTS is fried. When it goes bad, it defaults to telling the computer that the coolant temperature is something like negative 80 degrees, so it just POURS fuel into the cylinder. When it does that, it ruins the spark plugs (fuel fouled them). Once you get new spark plugs (gap them correctly), and get a new Coolant Temperature Sensor, it should run again.

 

Yup, I guess thats what I'm going to try first. If that doesn't work I'll dig a little deeper

 

Just an update.. thanks for all the tips....tested the CTS with an ohm meter...pegged it with a 1. Replaced the CTS and fired it up....runs great...actually better than I remember it running when I parked it I think when it was cold as in open loop the CTS has less effect on the engine so it would run but when it went closed loop it would flood the engine and stall. Still has the 2 year old gas in it so I am going to run some good injector cleaner through it with some fresh gas and go have some fun. just realized that the gas in the tank probably cost about a buck and a half a gallon...hope it will mix with the 2.50 a gallon stuff I am going to have to put in it oh ya have to get the %^@#! hatch to pull down..don't know whats up there yet.

 

Siphon out as much of the old gas as you can and fill it up with fresh stuff.

Don't bother the fuel injector cleaner. It's just snake oil and not strong enough to remove anything from the injectors. The system that hooks up to the fuel rail works or sonic cleaning. Run a couple of tanks of fresh gas thru before gong after the injectors.

 

I heard that too about injector cleaners. I was told GM has some injector cleaner that is pretty good a may be worth a try first. I will try and get as much of the old gas out as I can. Like I said on the previous post...it is running much better than it was when I parked it, even with the old gas...CTS sensor must have been going bad for a while.