Need advice please. 91 z28 conv with 305 TPI. Sat for 8months while being repaired from an accident. Got it together. Fired right up and ran for a short 10 minute trip to get emissions checked. Passed with flying colors. Ran out to get parts that evening and it suddenly died. Did not sputter just died. Would not start for 2 hours. Put a gas additive in with a full tank, then took off for a short trip and it did the same thing. It died about a mile from a chevy dealer so we limped it in for a diagnosis. They suspected fuel injectors and broke it down to confirm. They said that is it and the ac delvo parts are $175 each plus $470 labor ($1900 total). Before I invest in the adventure of changing these. Does it seem erasable that they just stop working aftter a few miles? I assume this is because they heat up? Do you think a couple rookies can handle changing the injectors? Thanks

 

Rookies can handle injectors. I would have suspected old fuel in tank and gone through the fuel lines before going to injectors...

 

Get a multimeter and ohm your injectors. Any injector under 12 ohms is a bad injector. If one is bad, change them all. Your injectors are Multecs and are prone to going bad.

Southbay fuel injectors sells complete sets of Bosch III for around 150 for a set of 8. It is easily doable in a weekend. DO NOT pay the dealer 2k for something you can do for 150.

 

Gas lastes for around 2 years b4 it starts 2 go bad even without additives. 8months wont hurt at all..
If it really is the injs do not pay that much at the dealer..

 

Thanks I won't be paying $2K that is for sure. Just seems strange it would go from run great to not running. I guess the heat causes the failure. Before I dig in I'll get it to stop again and check the resistance and do a fuel pressure check. I saw replacement injectors at Hawks and I've seen some suthbay threads. Both pro and con. Does the adapter become a leak problem on the soothsay Bosch III. Thanks for the support, we,ll get it done

 

You don't have all 8 injectors go bad all at once. No way.

If it's an instant-shut-off situation the problem is electrical in nature. A bad module, bad coil or other electrical malady. Electronics don't like heat. When they fail, they usually fail first when hot.

If it runs still, drive it until it dies again. IMMEDIATELY check for spark. That's where I would start.

Dealerships and most shops are "parts replacement" pros. They are usually good at unbolting stuff and replacing ti with new stuff (cost to be borne by you). Most shops can't diagnose their way out of a wet paper bag, however. Intermittent stuff they can almost never find unless it throws a code in the ECM.

 

I did confirm it has spark. I could hear the fuel pump whine. I'll check pressure next time. I agree, it doesn't make sense that 8 would fail. Unless the overload the computer some how? Any electrical checks?

 

Sold a ton of these injectors with the adapter over the past couple of years....thank God never had a problem to date !!!
If the car sat for 8 months, a fuel additive may not have done the trick if there was "gunk" in your fuel system.
You should check resistance on each injector...both hot and cold, if you have a noid light check to see if there is an injector
or two that isn't pulsing.
One last thing, if you decide to change your injectors, whether you purchase them from us or another company, do not let the dealers rip you
off, there is no reason to pay that kind of money! Good luck

 

One other thing. Had some welding done one the frame. Could that effect the computer module?

 

Thanks. What is a noid? Also if one or two are bad. Why does the whole engine quit? No sputter, just dies. I'll change them if bad just don't understand why it completely dies. Any thoughts?

 

If it's got spark, shoot a little starting fluid into it and see if it fires. If it does, you have problems on the fuel side. Possibly a bad ECM, or a ground has gone AWOL causing the injectors not to fire. It's still electrical in nature, in my opinion, it's just a question of WHAT electronics aren't working and why.

I suppose it's possible that welding could have caused something to "pop" in the electronics since the arc used in the welding process (MIG or TIG) is a high voltage spark, basically. Wouldn't be the first thing I'd blame, but it's possible,

 

Is it pretty easy to change ECM? Looks to be about the same cost as injectors? Do I just measure ohms across the installed injector? Does the vehicle need to be running. Or is it just measured when the car is off.

 

it isnt the ecm. i would bet $100 its your ignition module. takes 10 minutes to replace. it is inside the distributer. seen it a lot! like someone else says. check for spark when it kills. when you find you have none. replace it!

 

I'm not real experienced. I took a spark plug wre off and put a screwdriver in it held against the chasis. I saw a small spark so I think it has spark

 

My money is on ignition module too...

 

I agree, that the loosing power problem does not sound like a fuel injector problem. It seem like one would misfire. However the dealer and a local fuel injector manufacturer tell me it happens because the ethanol has shorted the coil, and this increases with heat. I found GM tech article talking about the ethanol problem on infectors used prior to 1993. Mine are original 1991. However the article talked about the cause being a misfire, not a total loss of power.

Anyway, I got the car back and took an olm meter to 5 that I could get to easily. Two whee 16.5 ohms, one was 15.5 ohms and a forth was 14.1 ohms. The fitth was 6.1 ohms. This was done cold. Anyway if I have read the threads correctly. The injector reading 6.1 ohms indicates tha I do have a failure and should replace all of the injectors, correct? If so I might as well do this, not expecting it to sole the problem, but if it does I guess we all have learned somehing new.

 

Replaced the injectors. Just ran the car for the day. Runs great. So my conclusion is the dealer's diagnosis was worth it. An injector was shorting the system and forcing a shut down. I don't know as much as most of you. I probably would have spent a Couple of weekends before I ever got a clue to check injectors. I appreciate the advice and support and hope this helps someone else.


Car started and ran fine for about 5-6 miles then died and would not start for about 2 hours.

Also, we followed the procedure for injector swap. Ost complicated repair I've ever attempted. We did fine. Maybe 8 hours. Thanks

 

Glad to hear you got it fixed. Electrical stuff.... gotta love it! Enjoy the car.