I need help, i just bought a 89 Z with the 305/5spd and it runs awesome, but after 10-15 mins of use it will turn off and wont start again till the next day or after a few hours. It will turn but just wont start like if it needed gas.

I replaced the fuel pump, alternator, battery and nothing. I figured it was the fuel pump, I installed the new one and it still does the same thing. Any ideas??

 

Are you getting any codes?

You need to check to see if you aren't getting spark or getting fuel.. That will start you in determining which course you need to follow

 

Rotor or ignition module

Start w the rotor, it's cheeeeeeeper

 

Remove your ICM bring it to your local parts store to have it tested, run the test 3-5 times to be sure it is getting warm enough to shut down.
While you have the module out inspect the cap and rotor. These distributors are known after time to go bad from use... the shaft begins to have excessive play in them and it ischeaper to replace the unit rather than to replace all the parts inside, I bought a reman. For 110.00 whereas all the parts to rebuild it came to 129.00+ tax

 

You need to determine why it won't start.

1. Run it in your driveway until it dies.
2. Pull a plug wire and test for spark.
3. If it has spark, test fuel pressure at the rail.
4. One of those two will be missing, report back when you figure out which one is it. I'm betting you're missing spark.

 

Thanks guys, I just got off work and I will try to find out if I have spark. I know its gotta be a simple fix, because it runs good when it starts.

I took it to my uncle and we did not get any codes.

 

Could be a clogged fuel filter.

 

the ICM (ignition control module) , the one inside the dist. . they are cheap enough . good luck .

 

So here is the update, the car still does the same thing. We tried two ECMs, a distributor, new air mass flow sensor and nothing.

The car has spark, fuel pressure, and no codes come up. I am sure now that it will be something simple, but the problem is we cant figure out what it is. I will keep you guys updated and I will let you know what it is wrong with it once i figure it out.

I am not giving up on this car, what makes me mad is I have a 1980 Z28 and it has never given me any problems. I was wondering if there was a factory defect on the 89 Zs??

 

It's the injectors. Measure the resistance of all the injectors when the engine is cold, then do it again when the engine shuts off. You'll find the problem then I bet. Doesn't cost anything to check and I bet money this is your problem.

 

To Afremont, thank you very much, it ended up beign the injectors. Thanks you everyone that helped, it took me a while to get back because i had a hard time finding the injectors and finally got them from a guy in Fontana CA for $120 they are remanufactured.

Car is running now, will post pics soon.

 

Hey Afremont/all,
I have a 91 Z28 doing very much the same thing. I've been fighting with it since July, and while I have found some pieces/parts that were good to get replaced they have not been the actual problem.
I have not checked the resistance of the injectors, and will do that this evening. But for my reference, if I don't find any that are 'obviously' bad, what ohm range is considered 'good' vs 'bad'?

 

Jesus, could you forward the information on where you got those injectors?

 

You can do some searching on "ohming" the injectors. I believe 12 Ohms was the commonly accepted lower limit for an acceptable injector, anything below that is drawing too much current and will overheat the ECM drivers. Measure them all cold and then when hot. If you see much of a change on an injector, then it's probably bad or on its way out. Change the injectors as a complete set. You can buy remanufactured Bosch III injectors from at least two different vendors, one is FIC and I can't recall the other right now.

 

sorry...FIC?

 

regarding injector types....is it true that the 5.0 and the 5.7 would use the same injectors since they are both "Z28"? I've noticed that there are sometimes distinctions between Z28 and RS, but I've not noticed any between 5.0 and 5.7... And if I happened to have access to a 90-91 T/A 5.0L, is there any reason I couldn't use those injectors for my Z28? I'm actually assuming/hoping that it is also multi-port injection but have not verified it.

 

http://fuelinjectorconnection.com/sh...php?groupid=72

There is definitely a difference between 5.0 and 5.7 injectors in terms of flow rate. A complete set of rebuilt Bosch injectors runs about $200 with o-rings and gaskets. It's an easy job, just take your time and get it right the first time. Don't replace one or two injectors, change them all.

 

I bought mine from a guy named Gonzalo. I send him a check first before he sent them to me, I trusted him and he delivered.

He is located in Fontana California his cell phone # is (909)520.1327

I know he said he had two types. they are remanufactured not new.