GMC S15 Pick-up

1986 GMC S15 Pick-up Fuel System   

Hello. I just replaced my crankshaft on my 2.8 engine.
After doing so , the engine will not start. It ran completely okay before. If I squirt gas into the TBI it will run as long as I do that. It has a lot of fuel pressure at the TBI. I clamped the return line to see if the regulator was working, and it did not help. I replaced the ECM. That got no results. I checked every line and connection over and over.I also checked to see if there was power at the fuel injector, when I probed one of the wires with the key on, the test light lit up. I got my wife to try and start it and the other wire did not light up any. the wire that did light up stayed lit the whole time. It has two fuel injectors on it. where do i go from here ? Could the prom/calpak chip be bad ? I haad to use my old ones in the new ECM. If so, where would I them ? Thankls for your time ,
Skip Pico

Have you checked for trouble codes, any found?

Do check the injector wires from the fuel injector to the ECM for opens (shorted would run all the time when the key was on because the positive circuit tests fine.

The ignition module could also be bad, but check the wiring around the distributor.

Do you have reference voltage from the ECM to sensors?

I have checked the troble codes and found none. It just flashes 12. On the firewall there is a thin square box with some wires coming out of it. It might be the Electronic spark control module E.S.T. Could that have something to do with it? I am not sure of the reference voltage from the ECM. I don't know how to check that. Could it be the Prom/calpax chip? I used my old ones. I was a mechanic for 5 years at a Ford dealership. . This one has me stumped. Of course it was back in the 70's I have been trying to keep up with all the new stuff.

The reference voltage is five volts (positive) to the sensor. Check at the TPS, one end of voltmeter to known good ground and the other to sensor electical connector.

It could be the electronic spark control, as the ECM needs spark reference to know when to fire the injectors.

Possibly the PROM, but not likely.

I will check out the voltage tomorrow. It is 10:07 PM here. I will keep you informed. Have a good night.

Hello, After checking connections again ad again I reached way back behind the Distributor and guess what I found. There was a four connection wire that was unpluged. I feel real dumb right now. I guess it happens to the best of us. The truck is running great. Go I still get charged for your service? Is the service just a one time deal? Thanks for your time, Skip

That would be the missing spark/cylinder reference that lets the ECM know when to fire the injectors.

A one time deal? I'm not sure what you are asking?

By the way, you replace the crankshaft only? What was originally wrong?

I replaced the crankshaft because it broke at the the second rod journel. The engine has 248,000 miles on it. I change the oil twice a year. I meet GM oil change requirements. It uses no oil in between oil changes. It has been really a good truck. I am wanting to see how long it will go. Plus it gets good gas mileage.
Is the 19.50 I paid for only one incident? I don't know how that part works. Thanks for your quick responce. Skip P.

This engine may hit 300k + if you don't work it to hard.

No oil use us great.

Your payment is intended for one time use, but your question will stay active for 2-3 months. If you have a question while this question is still active ask away- or questions for that matter.

Is this your only vehicle?

I have a 2003 Cadillac CTS with a luxury sport package. My wife has a 2004 Dodge Dakota 4x4 with a V8. Which sits in our driveway most of the time because of the gas.
I have one more question about my truck- the air condtioner works good, the problem is: I have to get the rpms up before the compressor kicks on. If I idle for long periods, the compressor shuts off. Then when I start out shifting gears it will come on and stay on until I get to lower speeds again. Is something being activated by the increase in voltage ? When the compressor is working the air coming out is cold.
Have a good night, it's 10:10 pm here, I'm going to bed. Thanks for your time again.
Skip

1986 GMC S15 Pick-up All Part Groups   

86 4x4 2.8 v6 auto oversize tires 205 to 235. ok a few things. above 35 (feels like rear) shudders pretty bad, midas did brakes all, front axles, idler arm, aligned, balanced. getting about 10 mpg should be close to 18 and now has sqeal to mid or rear end. tranny fluid ok smells burnt. all gears shift ok maybe a bit hard. pls help

replaced plugs, wires, air and fuel filter, pvc and new oil less than 500 miles

First off get the Midas boys to flush the fluid in the trans.They cost too much to burn up!
When they have it on the hoist, they can check the driveshaft to ensure it is straight and that the U Joints are good.

have check engine light, light is off when car started comes on when engine reaches operating temp (200ish) stays on until key is turned off. cant find anyone with older style code reader. any ideas?

Since it is temperature related the first that you might consider is looking at the egr valve and the switch that opens it. The EGR recycles exhaust through the intake manifold and is only supposed to do that when the engine has warmed up.
If you require codes read, you might consider looking on EBay for a cheap OBD 1
type code reader. They are cheap, and just another tool.