Cam and Crank Sensor Testing
I just had the motor rebuilt for my 1997 GMC K1500 (350 Vortec). After installing it into the truck - it will not start! My timing light shows that I am getting spark. If I shoot some starting fluid into the air cleaner housing, it will attempt to run.
There is nothing more disappointing or frustrating than a new engine that will not start!
I made a noid light out of an old taillight bulb, and I get nothing from every pin pair in the connector. I checked the cam position sensor (CMP) and the crank position sensor (CKP) using the procedure in your manual (24065, pages 6-15 and 6-16) and I get similar behavior from both. If I follow the book procedure to backprobe the signal (I used a paperclip) with the positive lead of my meter and connect the negative to a ground - I never get past 0.25 VAC on the CMP and 0.6 VAC on the CKP. If I backprobe the signal output and and attach my meter's negative lead to the signal return on the connectors - I see about a lot of variety with a peak of 3.5 VAC from the CMP, and a pretty steady 2.5 VAC from the CKP. Both connectors have a good 12 volt supply between the pink wire and ground.
Does probing the connectors produce a valid result? Does the fact that I don't get a decent reading between the connector and ground indicate a wiring problem?
Your advice will be greatly appreciated.
Before you go any further, do two things:
1) Check to see if any trouble codes are stored in the PCM
2) Check for fuel pressure
I'm not so sure your homemade 'noid light is a valid test. An actual 'noid light doesn't use a bulb, it uses an LED.
Since you're getting similar performance from the CMP and CKP sensors, I doubt if either of those are your problem. As far as the values you're getting, keep in mind that the manual states that those values are "approximate."
Fuel Injection Pain
Thanks for the response.
I am using Actron AutoScanner Plus (CP9180), and there are no codes.
I have a gauge on the port right now. When I turn the key on, the gauge peaks at 60-62 psi and then falls back to 56 when the pump goes off. I don't have the return blocked.
I tested each injector by keying the ignition on to pressurize the fuel system and then turning the key off. I then connected 12 volts to a pair of injector pins to see if the fuel pressure would drop. I repeated this procedure for each injector. Seven out of 8 injectors do drop the fuel pressure when energized, so I know I have 1 bad one.
I made the noid light with a bulb because the dealer I spoke with said that they use the 194 bulbs out of the marker light. I will make one out of one of my marker lights and try it again.
As mentioned in the prior post, if I shoot some starting fluid into the air cleaner box - it shows immediate signs of life.
I re-did the TDC and distributor installation, poured a little gas down the intake, and it fired right up (on 7 cylinders).
I decided to try running some SeaFoam through the fuel system before replacing the injector - and it worked! The engine is running on all 8.
I had codes for a bad O2 sensor and throttle position switch (TPS). The TPS had definitely had something leak on behind the O-ring. Replaced the TPS and O2 sensor and all is well. No codes!!
Good job! It's always good to check the basics before getting in too deep.