2600i question???

I powered the pump relay today where it runs all the time while the key is in the ON possition. IT did not change anything at all.....Still starts and dies right away..........HELP!!!!!

Have you check to see if the circuit board in the ECM is ok? The resistors in there like to leak and will ruin the circuit board and make the truck do strange things. Just something to check.

I posted how to jump out the check engine connector. . .until you do that, and see if any codes have been captured.. . .I do not kow what else to tell you.

The engine was running fine. . .and then you rebuilt it. . .and now it won't stay running. . .so maybe a wire somewhere isn't reconnected. . .and the self monitoring function of the ECM might tell you where to look.


Added edit. . .

The ECM controls the injectors, and normally the fuel pump, while the engine is running. . .but if the truck gets into a crash. . .it would be very dangerous to have the fuel pump running in case a fuel line gets ruptured. . .So the engineers have designed the ECM to stop operating the fuel pump if there is a loss of a "run" signal.

Your fuel pump relay is probably ok from your testing. . .but maybe a crank posistion sensor wire is pinched, or something else is wrong with wiring somewhere. Like a disconnected mass air flow sensor.

Like I said. . .posting some low res underhood pictures might help.

Ok there are a few photos....... I have removed the Air Flow sensor and the truck ran longer than it had so far....which wasnt long at all. I tried getting the codes off of it by grounding the green wire under the hood and checking the check engine light....It did nothing at all.

Here are the ECU diagrams. . .

From the diagram. . .I see a main relay. . . .which feeds electricity to the ECU and airflow meter.

The only thing I can tell you at this point is that you are going to have to verify power to the ECU, and point to point wiring integrity and current flow.

I would disconnect the air flow sensor, and then run your diagnostic test. . .with it disconnected, there should be a hard code set of 8.

Since you haven't got a code trapped yet, you need to try to induce one.

Try disconnecting the water thermosensor and see if you get a code. Or the Airflow meter.

And verify that the main relay is providing power to the ECU.

here are the pin-outs for the ECU. . .

Ok still cant get the truck to produce a "code" the check engine light will not go out at all......I dont know if it doesnt run long enough to do it or what. The TPS is good. I took it to a local shop and they tested it...its fine. I cleaned the MAS and it "seams" to be fine. The ECM has been worked on before...It had a recon sticker on it from "04"

At this point, I am unable to offer any other assistance, as what I have placed in this thread indicates test points which can and will need to be tested for voltage.

An LED test light can be used in conjunction with a paper clip to back probe the connectors for voltage verification.

A digital multimeter can be used to obtain precise voltages.

You really need to just start checking fuses and verify that they aren't oxidized on the blades and that sort of thing.

The third picture in my last post shows voltages that should be entering the ECU. And where they should be coming from.

If you don't have power to feed the ECU itself, it cannot operate the rest of the subsystems. The truck will not run.

Maybe that is where you need to start your diagnoses.

On another tack. . .what did you do in terms of rebuilding your motor?

Was it done in the frame, or did you remove it?

The other thing you need to check is that engine to body grounds are all good. Maybe the ground cable to the body is problematic.