1990 bounder P30 with Chevy 454 Starting Problems

[chilibeerman]

Help! 454 Chevy TBI quit running while idling. Injectors sprayed for a while then quit also. We replaced the ECM, ignition switch, oil temp sending unit and fuel filter. Fuel pump makes noise then shuts off like it is supposed to after a few seconds.

Voltage at fuse block for ECM ignition and ECM Bat is not 12 volts but all other voltages at fuse block are 12 Volts.

Does anyone have a wiring diagram for 1990 bounder with Chevy 354 or knowledge in this area. We plan on checking fuel flow and pressure today.

The ECM is getting no 12 volt power that we can tell and when we hook up the OBD is says ECM not responding.

[markndeb1970]

if you changed the ECM you need to have it programed by a dealer. It will not run, they are not a plug and play item.

[gauto5150]

The ECM does not need to be programmed by a dealer. Not on a 1990.

[gauto5150]

Originally Posted by chilibeerman

Help! 454 Chevy TBI quit running while idling. Injectors sprayed for a while then quit also. We replaced the ECM, ignition switch, oil temp sending unit and fuel filter. Fuel pump makes noise then shuts off like it is supposed to after a few seconds.

Voltage at fuse block for ECM ignition and ECM Bat is not 12 volts but all other voltages at fuse block are 12 Volts.

Does anyone have a wiring diagram for 1990 bounder with Chevy 354 or knowledge in this area. We plan on checking fuel flow and pressure today.

The ECM is getting no 12 volt power that we can tell and when we hook up the OBD is says ECM not responding.

Jumping A and B will give you a manual way to obtain codes. You'll have to count the flashes. It will start with code 12 and go 3 times, then all the other codes will flash 3 times and end with code 12 again to let you know there are no more codes.
Code 12 is normal.
However, if you're getting the initial fuel pump run and stop you may have a problem with the distributor. The computer needs crank signal to run the fuel pump. Typically on this ignition system, the distributor module, pickup coil, and main shaft (with magnetic weight) are all prone to fail after time. I've dealt with 100s of these failures as a mechanic.
If you can use a scanner and see if you have cranking RPM that would definitely help.
But first things first, do you have the "service engine soon" light illuminating with the key on? If not you need to start there. There is a fusible link that supplies voltage to the computer and sometimes just corrodes or breaks over time.
I can definitely help but I'd need to know in more detail how and why you've replaced the pieces you have so far. And what diagnostic tools you have to test (scanner, test light, mult-meter, stuff like that...).
Let me know!

[Dave78Chief]

I do not have the wiring diagrams but if you have to get the manuals (GM Light Truck) they are a 3 volume set.

Service Manual



Unit Repair Manual:



Wiring Diagrams:



Typically available om EBAY:
1990 Chevrolet light truck manual | eBay

Make sure you get the Service and Wiring Diagrams that have the "P" in the title.

Jumping A and B will give you a manual way to obtain codes. You'll have to count the flashes. It will start with code 12 and go 3 times, then all the other codes will flash 3 times and end with code 12 again to let you know there are no more codes.
Code 12 is normal.

If he is not getting power to the ECM will he even be able to do that?

Dave

[gauto5150]

Dave,
I'm not exactly sure he's getting power, but that's one way of finding out.
Besides that, even if he's able to get codes, they probably won't be of any significance to why it there's not injector pulse or fuel pump operation. The monitoring systems on an OBDI system aren't as intricate as the newer computer systems.
We just need to know IF that manual way works at this point.
Gary

PS - I have all the illustrations and literature in the books that Dave posted above and can send copies if needed.

[chilibeerman]

Originally Posted by gauto5150

Jumping A and B will give you a manual way to obtain codes. You'll have to count the flashes. It will start with code 12 and go 3 times, then all the other codes will flash 3 times and end with code 12 again to let you know there are no more codes.
Code 12 is normal.
However, if you're getting the initial fuel pump run and stop you may have a problem with the distributor. The computer needs crank signal to run the fuel pump. Typically on this ignition system, the distributor module, pickup coil, and main shaft (with magnetic weight) are all prone to fail after time. I've dealt with 100s of these failures as a mechanic.
If you can use a scanner and see if you have cranking RPM that would definitely help.
But first things first, do you have the "service engine soon" light illuminating with the key on? If not you need to start there. There is a fusible link that supplies voltage to the computer and sometimes just corrodes or breaks over time.
I can definitely help but I'd need to know in more detail how and why you've replaced the pieces you have so far. And what diagnostic tools you have to test (scanner, test light, mult-meter, stuff like that...).
Let me know!

Thanks we plan to check the 2 second fuel pump run to see is that is happening. If that occurs then on to the next step. We are NOT getting power to the ECM. We changed the oil temp sender because we were getting up and down readings on the gauge when it was running. The ignition switch was not getting a ground on G2 so we replaced it. If you could e-mail the wiring diagrams that would really help. We have most of the diagnostic tools. When we use starting fluid it will start and die. What part of the distributor system would go bad to cause no fuel pump?

Thanks everyone. We are not novices but this one has us stumped.

Ed

[chilibeerman]

We are not getting the check engine light with key on.

[chilibeerman]

Originally Posted by chilibeerman

We are not getting the check engine light with key on.

my e-mail address is chilibeer@cox.net

[gauto5150]

Originally Posted by chilibeerman

Thanks we plan to check the 2 second fuel pump run to see is that is happening. If that occurs then on to the next step. We are NOT getting power to the ECM. We changed the oil temp sender because we were getting up and down readings on the gauge when it was running. The ignition switch was not getting a ground on G2 so we replaced it. If you could e-mail the wiring diagrams that would really help. We have most of the diagnostic tools. When we use starting fluid it will start and die. What part of the distributor system would go bad to cause no fuel pump?

Thanks everyone. We are not novices but this one has us stumped.

Ed

OK, if it starts and dies with starting fluid then the distributor is OK. It wouldn't run at all if the pickup coil was bad, there wouldn't be any ignition.
I've sent you a connector view of the computer. You'll see a pink/black wire and an orange wire. Those are your main power inputs on the computer. I'd check those first along with the couple of grounds (which are black/white wires). If you're lacking any of those, jump them to a ground or power source and see if it starts. I'm guessing the orange wire has lost it's power.

[Phobos]

Just a thought here, but have you checked the ECM relay? They are usually located in or around the fusebox and are pretty generic. A good way to test is to pull a known working one (like the A/C) and swap them around.
Like I said, it's just a thought and I know electrical gremlins can be very irritating!

[chilibeerman]

Latest news. After a day of tracing wires I cleaned up a ground wire going to some kind of circuit board that is attached to the start solenoid. I asked my brother-inlaw to crank it and it sprayed fuel and the check engine light came on while cranking. It tried to start then died and we could not replicate what just happened. Does anyone know what the circuit board controller is? It is made by a company named Intellitec.

[chilibeerman]

Pictures of circuit board

[gauto5150]

I believe that is the board for starting and operating your generator. I don't think that has anything to do with your issue.