I think that my injectors are on constant pulse!! My car wont start after replacing the injectors and preasure regulator. I had a couple of injectors that were bad so i replaced them all now the motor is flooding. I ran a fuel preasure drop test and I am going from 40 PSI to 0 in about a second. In an effort to figure out the preasure drop I checked the injector voltage on both sides of the injector pigtail at several injectors. Result was 12 volts on the fused feed wire and .9 volts on the ECM injector driver wire on both banks. Is this right?? My manuel says to use a noid light but all I have is a dvm. I am getting gas in my oil and my spark plugs are drenched. I checked the wiring from the ECM to the harness at the back of the block and all the wires look good. The ECM has been replaced and I even opened the new one up and checked all the resistors with an ohm meter. All the resistors were working properly. Could my PROM be bad? The ecm motor and harness are out of an 88 camaro but it has an aftermarket PROM for an 89 GTA 350 that was installed by the previous owner. This should have kiled the cold start injector so I dont think that its a faulty temp sensor. If the PROM was bad wouldnt the ECM flash the code for that? My fuel pump is working normally and has been replaced by a compitant mechanic (myself) so I dont think that is the problem. I am at my wits end with this, please help me.

 

Pull the vacuum line off the fuel pressure regulator and have
someone turn the ignition on and right back off just to run the
pump for a second or two. See if gas comes squirting out of the
vacuum line nipple of the regulator.

It sounds like you are getting gas leaking past the diaphram in
the regulator and it's getting drawn into the intake through the
vacuum line and drowning the engine.

 

I checked and I am not leaking fuel through the regulator vacuum hose. Any other ideas?? Thanks for the help so far guys.

 

Sure, your injectors could be sticking open, or for some reason they're getting kicked on, but not off.

 

The injectors are brand new units from accel. I didnt know about the quality issue till after i bought them but I believe that they are fine. I checked my wiring today with a meter and am getting 12volts on the black wire and .9 volts on the black with a stripe (ecm injector driver). An Ohm check showed under 1 ohm from the injector pigtail to the ECM wiring plug so I belive that the wire is fine. All the connections were good. I went ahead and ordered a new stock GM EPROM today so I will install that when it gets here and I will hit the junk yard this weekend and see if I can find another wiring harness. Thanks for the help.

 

1slow60-

I can't offer you much, but I notice it seems like you were unsure about the wiring for your injectors. I can offer you some information that will help you determine if the injector wiring is messed up. I had a wiring problem with my injectors, so right now, I am looking at some info I got from the mechanic who repaired my car, and did a great job of it I might add so I trust his work.

As you know, the injectors have power coming in and power going out. It's basic electrical knowledge; power needs to continue flowing so it exits the injector and grounds.

The paper I am looking at says at the top that this is for a 1985 GM VIN F 5.0 L TPI setup. I'm not sure, but I would assume that the info I have would be the same for all 1985-1989 Tuned Ports, because only the MAF and a couple grounds were different in 1985 than the wiring for 1986-1989.

It says here that PIN D16, for INJ1,3,5,7 in key off engine off tests have a minimum OHM level of 2.50, and a max of 5.00 . If its less or more than that, its out of spec. The specs are the same for injectors 2,4,6,8.

With the key ON and engine OFF test, injectors 1,3,5,7 should have VOLT levels of MIN 10.89 VOLT and a max of 13.31 volts. For AMPS, the MIN is 2.38 and the MAX is 4.75. Obviously if the numbers you have are not in line with these then its out of spec.

I realize this might not make sense and it might not help much, but take it as you wish and I hope it helps you some. If you need more info, or better yet-would actually like a scan of the papers I got this info from, let me know and I'll be glad to help.

Kev

 

Man if you could get me those scans it would be great!!! I have been digging through every book that i can get my hands onto but havnt found anything like that. Honestly every wiring setup and troubleshooting section really bites for the problem that I am having. My biggest problem is that if the EPROM has died it could cause all the problems that I am having. Also when ya consider that the ECM grounds the circuit to fire the injectors it makes it really hard to trouble shoot the harness for a short. The motor and harness was out of a running car with a slightly botched harness. The previous owner redid the cooling fan harness for a single fan when the stock duel fan died rather than spend the cash on a replacement fan. The rest of the harness seems to be fine though unless I pinched a wire when I slid the motor into my firebird. The reason that I ordered the EPROM today is that I have a 5spd in the car with the 350 and I think that the stock 305 chip will be better suited to the motor so that kills 2 birds with one stone. I follow everything that you were saying as I am an electrician by trade but computers sure are not my specialty. When I was younger I worked on power lines but now I am an electrician in the Navy. Although these silicon based things sure arnt the same as copper and aluminum wires with transformers. Thanks for the help.

 

I'll get them papers scanned for ya tomorrow. What's your email addy so I can figure out how to send them to ya?

Kev

 

Thanks once again. The email addy is jaysbarandgrill@aol