1985 Oldsmobile Ciera



January, 10, 2010 AT 9:29 AM

Electrical problem
1985 Oldsmobile Ciera 4 cyl Front Wheel Drive Automatic 100000 miles

Replaced a cracked cylinder head on this 1985 2.5 liter tbi gm iron duke engine.

After replacement the rocker arms where torqued or adjusted incorrectly causing an engine misfire-backfire through the exhaust. Lost fuel injection at the fuel injector after this.

The rockers where then readjusted and compression tested good. Car starts and run with prime through the tbi throat. Injector gets no pulse(tested with noid light) and the iac also has no activity when tested with the noid light.

Replaced an oil pressure switch. This did not resolve the NO Fuel problem.
The ECM fuse and fuel injector fuse checked OK.

The ignition control module tested Good.

Replaced the fuel filter and removed the fuel pump in the tank as this is what initially I suspected as being faulty.

The fuel pump tested good out of the tank using a 12volt aligator clip to test. This confirmed by a local autoparts house

The oil pressure switch was not tested. Just replaced.

Could the pcm be the problem? Car started and ran before the cylinder head was replaced. It now starts but cannot get fuel to the injector. No pulse as previously indicated?


8 Answers



January, 10, 2010 AT 10:14 AM

Welcome to the forum, Any fuses that you checked, did you use a testlite on the fuse circuit, to see if the circuit was hot? With the key on, do you have voltage at the injector plug? Did you check fuel pressure with a gage? With the engine cranking, do you have good voltage and ground at the fuel pump connector.

I don't know how the autostore tested your pump? A no load test won't work. I've seen faulty fuel pumps that would run just fine on the work bench, hooked up to battery voltage, but, they wouldn't run at all, with a load on it.

Any trouble codes?



January, 10, 2010 AT 12:01 PM

I did not test use a testlight on the fuse circuit. I visually inspected and tested the fuses with an analog multimeter. I turned the ignition to the " on" position and turned the radio on. Radio works until I Pull the 10 amp fuse to the radio in the fuse block where the other fuses for the fuel injector and the ecm are located.

I have not tested for voltage at the injector plug with the key on. I just assumed the noid light would indicate this? Wrong presumably as the Noid light would probably detect the pulse from the ecm not the voltage at the plug?

I did not check the fuel pressure with a guage. Fuel was getting to the rail connected to the fuel filter in the engine compartment initially after the readjustment to the rocker arms and a check for compression.

I don't know what the pressure was but it was getting to the tbi. But no spray from the injector.

After this I presumed the fuel pump was faulty because I could not here the pump being enerigiized. The pump was removed. The pump was not load tested at the Parts store.

Purchased a Noid light set to check for injector pulse after this. There was no injector pulse as confirmed by the noid light test. The fuel pump was reinstalled after this as I presumed the injector was not getting signal from the ecm/pcm. I was getting no noid light confirmation when I connected the light tor the IAC connector. This led me to think the PCM was not functioning correctly for any reason?

Then I replaced the oil pressure switch.

I tested the voltage at the connector to the fuel pump when it was disconnected. Not with the engine cranking. Only when the harness connector had been removed fron the fuel pump connector. Appeared to be 12 volts at the connector.

I do not have a remote starter setup.



January, 10, 2010 AT 12:39 PM

One thing, if the computer doesn't see a rpm signal, it won't ground the injector. Shouldn't have any effect on the voltage at the injector. You can use the meter to check for voltage at the injector, use chassis ground.



January, 10, 2010 AT 1:17 PM

The RPM signal comes from the crankshaft or camshaft sensor?

This vehicle has a distributor with a rotor, pickup coil, and as well as the ignition control module and separate ignition coil. I do get spark. The initial rotor was installed incorrectly and when the engine was turned over it completely broke the rotor. I replaced it and get plenty of spark but as you know I cannot get fuel at the injector.



January, 10, 2010 AT 2:31 PM

I understand, you have a distributor, with fuel injection, there still has to be an rpm signal to the computer, for injector ground. That signal comes from the ignition module. Because you have spark at the plugs, I think the pick-up coil is ok. Did you get a chance to check for voltage at the injector plug, key on?

Purple wire with white tracer, at the distributor, carries rpm signal to computer.



January, 10, 2010 AT 5:31 PM

The car has been pushed into the driveway and the battery was removed. Had - 25 degree weather over the weekend. Did not want the new battery to freeze. Cannot get to that testing until next week.

Wouldn't the noid light indicate this. I tried this and there was nothing with key on or initiating the starter.

I presumed the module was good since it tested good at part stores.

Thank you for your help.



January, 11, 2010 AT 9:47 AM

I hear you about the cold. If there is no ground, the noid lite can't do anything. Even if there is voltage at the connector, without ground, nothing happens.



January, 11, 2010 AT 10:39 AM

There was another detail I forgot to write about. In the harness thathas leads to the blue and red wires for the injector is a 2 wire clip(clip is a 2 prong connector--The wires are yellow with a brown stripe leading to the 2 prong connector that is brown). This is not connectede to anything. I looked several times for the recieved clip for this and could not locate? Initiated this work several months ago. I cannot recall or se where this 2 wire connector goes. There is a single prong 1 wire connector that is from a small square plastic attachment on the firewall near the center/drivers side firewall. This also has a brown connector clip with only 1 prong. This is also disconnected. I could not make the 2 meet. Wires where not long enough. I'm not sure if there is some clip to connect these or if this is part of the problem.

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