Sorry for the long post but there is a lot of information to provide. I know this is 3rdgen F-body forum, but I also know there are some quite knowledgeable TPI guys on here. I am working on a buddy's '89 vette vert that is mint, only has 10k miles. Yes, that's right. He never drives it. just washes it and looks at it. Anyway, he called me up saying it's running like crap and keeps stalling. So, first thing I do is ohm the injectors. sure as shyt has 3 shorted injectors. Bought a set of new delco injectors and put them in with a new set of delco plugs. Put it all back together and it runs, but check engine light flickering, purge solenoid clattering, cooling fan coming on and off. Suspect faulty ecm. Try used 165 ecm with prom from original ecm and clean plugs, now it starts and runs great with the exception of an intermittent miss at idle. Spray the wires down with 10% salt solution and found 2 bad wires. Put a new set of delco wires on and it starts and runs fine. Bam, done right? 2 days later, he goes to move it out of the garage to wash it (again) and it won't start. I go to check it out and it will crank like it has no spark. hold it to the floor for clear flood and after about 3-4 secs of cranking, it tries to start only to surge 2 quick times and fart out the intake with a big puff of white smoke coming out the MAF to throttle body boot. Pull the plugs, all are wet with gas. check for spark, seems very weak to me. Didn't have my ST-125 so just used a clean plug grounded on the ex man. pulled the cap and rotor, all looks good. cleaned the terminals inside the cap put it back together with clean plugs again and it does the same thing, starts with 2 quick surges and a fart out the intake. double checked the plug wires and they are correct. I didn't have my tech2 and pin e adapter so couldn't check any data. No check engine light on except for bulb check with key on. Light does blink with first key on (prom check right?) I'm suspecting the used ecm I put it. tried disconnecting the MAF, same results. took a fuel sample, clear gas no water or alcohol. it's got good compression. disconnect all the injectors and ohm again, all about 16ohms. try to start with injectors unplugged and it tries to run just on the fuel in the cylinders but no surge or fart out intake. didn't have any carb cleaner or anything to try as a secondary fuel source. Something just up and took a dump. Any ideas what it is? Any other ideas on what to check next? Thanks for your time and input.

 

Did you check fuel pressure?

 

I did not check fuel pressure with a gauge. I did not have one with me. (this car is not at my house, although it may be soon for ease of working on it). I can hear the fuel pump running on key up. I checked for fuel pressure at the test port by depressing the schrader valve and there was plenty of pressure there. I know, I know, it's not a gauge. I don't believe this is fuel pressure related since 2 days ago it started and ran just fine. I don't know if the 'vettes use the little black piece of rubber hose between the fuel pump and the feed line inside the tank or not but if they do I don't think it's ruptured or leaking but a fuel pressure gauge is on the list of items to take with me to his garage this week.

 

OK:

So all these misc symptoms about "check engine light flickering, purge solenoid clattering, cooling fan coming on and off" ... were these present before the injector change? I'm guessing .... not?

In that case, it was something you did while changing the injectors.

Put the old ECM back in. Keep it, one variable at a time. Then:

Go back and check your work.

In particular, locate every ground wire you touched, and make sure it's securely bolted down and not broken or damaged.

 

"So all these misc symptoms about "check engine light flickering, purge solenoid clattering, cooling fan coming on and off" ... were these present before the injector change? I'm guessing .... not?"

Ever hear that saying about assuming? You guessed wrong. All of these symptoms were a result of a bad ecm due to the shorted injectors. Of course I double checked everything I did. I switched the original ecm and a used ecm a couple of times. each time I put the old ecm back in, it would run like crap. Different ecm and it started and ran fine. Until now.

And I didn't touch a single ground wire.

 

Well good luck; you're obviously too intelligent to need any help from some lowly generous person like me who can't read minds.

 

ok, ok....I deserved that. Please allow me to retract my previous statement about assuming.

all that aside, I am interested in any suggestions anyone has. I went over this thing paying very close attention to everything that I had my hands on while replacing the injectors, spark plugs, and wires. That's the first thing I do when something goes wrong after a repair. FWIW, I am a former dealer service tech and used to do heavy engine repair. I am well versed in taking things apart and putting them back together EXACTLY as it came apart. Everything went together smooth, no problems at all. I'll update this after I get to look at it with the scan tool, fuel pressure gauge, etc.

 

fuel pressure is rock steady at 43 psi KOEO. Spark was strong enough to jump the gap on a ST-125 spark tester. Engine would not start with starting fluid sprayed in the intake. Have good injector pulse. Could not read data stream from ecm due to not having an a/c power adapter for Tech2 or the 12v battery leads. Tried another ecm and it started right up. No idea what is wrong with the 2nd ecm since I couldn't read the data stream. May put the bad ecm back in after I find my power cable/adapter just to see if it will communicate or if there is something obvious in the data stream.