2600i question???

I have a 1990 2600i. fresh rebuild on the motor, cleaned out the gas tank. New fuel pump, filter......My problem is that it will start but then dies like it has no fuel.......What I think is happening is that the fuel pump is loosing signal to pump once the engine starts......Has anyone ever had this problem before and or have any ideas? Its fuel injected and its driving me nuts. Thanks for the help.

double check the fuel filter and also check the grounds if you cleaned the tank it might be loose

Does it die as soon as you let the key come back to the "run" position?

How many miles are on the truck itself.

Do you have access to a wiring diagram?

Is the truck modified from stock in any way whatsoever?

It runs for a sec but if you try and give it gas it dies right away, but it will only run for a second anyway even without pushing the gas. I have checked the filter and the pump they are both good....it shoots gas out the filter very well while trying to start The engine is stock with no mods to anything. New plugs, wires, cap and rotor. the timing seems to be right as it will try and start right off. It seems to be a fuel related problem but I dont really know. Its an automatic if that makes a difference.

I wans't able to get to a wiring diagram today. . .

But I suspect you have a problem with something other than the fuel pump.

As long as you have a little pressure at the rail, fuel is being delivered. The pressure drops off and then the vehicle stalls. . . .

The main fuel delivery (electrical) system is byassed during cranking. There is another circuit that should be active and that isn't.

Maybe a fuel pump relay.

Have you checked all the fuses and fusible links. . .like maybe one that says ECU or engine on it.

Have you tried starting the engine in neutral?

The other thing to look at which is pretty simple maybe is if the connector at the air flow meter is loose. A lot of people take the wire off that is supposed to secure the plug. . .and if it's not making good contact. . .systems that need the electrical signals don't get them.

If you could post a couple pictures (LOW resolution) of your underhood area. . .it might help.

Added edit:
In looking at your EFI system diagram. . .your system doesn't use an air flow meter with a potentiometer. . .so in seeing that, I don't think the problem is going to be found there.

From Alldata. . .

Fuel Pump Relay (Circuit Open Relay)

Perform tests in the order listed.

TEST 1 - RELAY SWITCHING FUNCTION CHECK

Disconnect relay from its harness connector.
Apply 12 volts and ground to the relay terminals listed below and check for the correct result.
12V/Grnd - CORRECT RESULT
"STA"/"E1" - Energizes relay, connects terminals "B" and "Fp" (continuity).
"B"/"Fp" - Energizes relay, 12 volts becomes available at terminal Fp.

If results are not correct as described, replace relay.

TEST 2 - RELAY RESISTANCE CHECK

Check resistance between the following relay terminals.

"STA"/"E1" - Resistance...21 - 43 ohms
"B"/"Fc" - Resistance...109 - 226 ohms
"B"/"Fp" - Resistance...infinite (no continuity)

If results are not correct as described, replace relay.

TEST 3 - RELAY CIRCUIT (WIRING) CHECK

Check voltage at the following terminals with the relay installed, under the conditions listed below.

3A - IGNITION "OFF"
No voltage at any terminal.

3B - IGNITION "ON" ENGINE NOT RUNNING

Terminal "STA" - 0 volts
Terminal "B" - 12 volts
Terminal "Fp" - 0 volts
Terminal "Fc" - 12 volts

3C - IGNITION IN "START" POSITION (CRANKING)

Terminal "STA" - 12 volts
Terminal "B" - 12 volts
Terminal "Fp" - 12 volts
Terminal "Fc" - 0 volts (or nearly zero)

3D - IGNITION "ON" ENGINE RUNNING

Terminal "STA" - 0 volts
Terminal "B" - 12 volts
Terminal "Fp" - 12 volts
Terminal "Fc" - 0 volts (or nearly zero)

NOTE: Relay terminal "E1" is a ground.

If voltage at any terminal is not correct, check the wiring associated with that terminal.

If 12 volts is present at terminal "Fc" during engine cranking or engine running, and the engine dies after starting, check for open in wiring between that terminal and ECU terminal "1i". If wiring is OK, ECU is not receiving a "crank signal" or "engine run signal" or ECU is defective.

Here's the other diagram I found, showing another view of the circuit in its entirety:

check your mass air flow sensor my 2600i did the same thing when the mass air flow sensor went bad

If wiring is OK, ECU is not receiving a "crank signal" or "engine run signal"



When trouble occurs in the main input or output devices, test the system to find the cause. During testing, failures of input and output devices are retrieved from the control unit as malfunction code numbers.

NOTE: The control unit constantly checks for malfunction of the input devices. But, it only checks for malfunction of output devices in a 3 second period after the ignition switch is turned on with the test connector grounded. If there is more than one failure code present, the lowest number malfunction code is displayed first, then the subsequent malfunction codes light up in order.

NOTE: This method may only be applicable to systems with a test connector and a Malfunction Indicator Light (MIL) or CHECK engine light.

INSPECTION PROCEDURE



Warm up the engine to normal operating temperature and then turn it off.
Ground the test connector (Green: 1-pin) with a jumper wire. NOTE: The connector is located next to the Self-Diagnostic Connector.
Turn the ignition switch to the ON position.
If the CHECK engine light illuminates, goes off, and stays off no codes are present.
If the CHECK engine light illuminates, goes off, and then starts flashing, codes are present.
Start the engine and check for additional codes.
If any codes are retrieved, repair the cause of the problem, refering to the COMPUTERIZED ENGINE CONTROLS SECTION for procedures as needed.
AFTER REPAIR PROCEDURE



Erase the malfunction codes from memory by disconnecting the negative battery cable and depressing the brake pedal for at least five seconds. Reconnect the battery cable.
Ensure that the engine is at normal operating temperature, then ground the test connector.
Turn the ignition switch to the ON position.
If the CHECK engine light illuminates, goes off, and stays off no codes are present.
If the CHECK engine light illuminates, goes off, and then starts flashing, codes are present.
Start the engine and check for additional codes.
If any codes are retrieved, repair the cause of the problem, then perform after repair procedures again.


If you have a bad crank sensor. . .or something like it. . .you might be getting a non run from it. . .

I will be checking everything today and tomorrow.....Thanks for all the info.....I will let you know what I find out.