Class A 1996 Chevrolet 454 engine starting problem

Ok, I think it may be time to look at actual wiring diagrams and start measuring voltages. If you don't have a meter, a 12 volt trouble light will do just as well. In the following link toward the bottom are diagrams to the ECM. You will have to join the group to be able to open the picture files.
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?337-16196395-PCM-Information
While it states ECM part number 16196395, it is still the same ECM as you have, even though your part number may be different. Also, a Google search on "16197427" brings up tons of info, as it is one of the favorite ECM's to use in custom fuel injection systems.

One other question, when you turn the key on, does your check engine light turn on? If it doesn't, you do not have power to the ECM.

The OP stated he did not smell fuel when he pulled the air cleaner, which clued me to ask to see if the injectors click when the key is turned to run position (not start). By testing this pre-start condition first, we don't care about the spark, as the ECM is not even looking for dizzy pulses in a pre-start condition. We are testing if the ECM even has power, as a power failure will result in both no spark and no fuel or injector pulses. I'm making an assumption he does not have a volt meter to go poking around to confirm the ECM is powered up, so this is the only way I can test that.

When troubleshooting, it likely one single problem causes many symptoms. So to draw any conclusion, each symptom must be isolated.

BTW: To the OP, you stated you could hear a click, but did not pinpoint the location of the click. I would suggest unplugging the injectors and see if you still hear the same click. If you still hear the click, then it was not the injectors you heard.

Daveinet wrote:

Trail-Mate wrote:
On the TBI GM Motors the module in the distributor will cause this issue. Random starts then No start at all. Easy to change and not expensive. If this does not solve it then connecting a fuel pressure gauge to the port in the rear of the TBI to test Pressure. Peak Pump pressure on the TBI motors is about 15-16 psi, and regulated by a regulator in the back of the TBI, There are way to change the regulator pressure but would have to look up how to do it, but the regulator is not your problem anyway.

I'm sorry, I disagree with you. There is not any sensor anywhere on the chassis that will prevent the pump from pumping fuel when the ignition is first turned on. This is a pre-start condition that is commanded from the ECM, to provide fuel in preparation for the engine to start. This occurs regardless of if the engine turns over or not. Same with the injectors. The injectors are pulsed initially, regardless of if the engine turns over. Basically, they put some fuel (rich mixture) into the intake so when the engine cranks, it will start.

See, if we hear the injectors fire when the key is turned on, then we know there is power to the ECM. Right now, we have no proof the ECM even has power. As a matter of fact, there is some indication that the ECM is not getting power, because of the lack of fuel when the key is first turned on, as well as the lack of spark, once the engine is cranking. So, that is the reason we want to listen for the injector pulse when the key is first turned on (before cranking). If we do not hear that injector pulse, then the ECM has lost power, and all these other symptoms are secondary.

He never said the pump doesn't run, he said there is no spark from the coil

There should be two plug ins on coil.One is a jumper that plugs into module on distributor,other supplys voltage to coil.Unplug second one and check terminals in plug for voltage with key on.Take care of no spark propblem first because when cranking if no spark there is no signal to ecm to fire injectors to keep from flooding engine with fuel.Fuel pump will still run its few seconds and relays click.I beleive on this year fuel pump relay is controlled by ecm so ithink your problem lies in ignition system.This is a stand alone system with only a wire going to ecm yelling it when there is a spark signal.

Yes, engine always cranks.

The click is the fuel pump relay dropping out after about two seconds.
Could be a bad or intermittent ignition switch.

IF you are not sure of where the click comes from, put a stethoscope right on the injectors when you turn the key on. Poor mans stethoscope is a screw driver touching the injector and the handle stuck in your ear.

My gut feeling is, (especially after you mention mechanic messing with the ignition) is the ECM not getting power. I need to go look at some documentation on what feeds the coil, but what I will want you to do is hot wire the coil, and see if it starts. I just can't tell you which wire to connect to the battery. I won't be able to look it up till tonight.

BTW: I assume that the engine cranks every time you hit the key, correct?

I hear a click forward of firewall after I turn ignition to On and before cranking. Engine will start sometimes after a mechanic works on ignition problem and runs fine. I can restart it several times. But after a few hours or next day it will not start, same old problem -- no spark from coil.

I appreciate everybody's helpful comments.

GeorgeFl9483 wrote:
The injector pump is heard when key is turned on, and before engine is cranked. The distributor cap, rotor, coil, and module in the distributor have been replaced.

OK, I want to make sure I understand your answer. By injector pump, do you mean that the injectors themselves click? Is it safe to assume you do not hear the fuel pump, as it is in the tank?

Incidentally, if the coach has been sitting a while, the pump may not run long enough to get fuel all the way up to the injectors on the first try. Yes, there should be a check valve in the pump that would prevent the fuel from running backward down the line, but it may still leak back slowly.

have you checked all fuses ? Shold be at least one marked ignition.Check for voltage at coil and module with key on as suggested