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HDGENE
HDGENE, ASE Master Tech
Category: Chevy
Satisfied Customers: 5276
Experience:  25 years Auto experience, Ford, GM, Chrysler, Asian & European
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95 chevy 7.4. Truck set in barn years. Drained fuel. Cleaned

Customer Question

95 chevy 7.4. Truck set in barn for two years. Drained fuel. Cleaned out fuel lines. New fuel pump and filter. No has to tbi so had tbi injectors cleaned. Still no has to tbi. Checked electrical to tbi and it's good. Checked and no spark to plugs. Cheched fuses they are all good. Replaced coil still no fire to plugs. Still no has and no fire. Any suggestions?
JA: When did you last fill the tank? And do you smell gasoline around the engine?
Customer: Yes i can smell gas but nothing to tbi
JA: What is the model/year of your Chevy?
Customer: 95 3500 7.4
JA: What year is your Chevy?
Customer: 95
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes.
JA: Anything else you think the mechanic should know?
Customer: New fuel pump
Submitted: 10 months ago.
Category: Chevy
Expert:  HDGENE replied 10 months ago.

Hello, you have power but no pulsing ground signal to the injectors, no fuel flow? You said you also have no spark. Is the truck equipped with a security key? Do you have oil pressure when cranking the engine? No diagnostic trouble codes stored?

Customer: replied 10 months ago.
Im not sure about security key..its a normal chevy key. Engine will turn over and seems to have oil preasure
Customer: replied 10 months ago.
The truck was running perfectly when put in the shop. Was my father's truck. It has about 68,000 miles on it. But he had chevy Dealer put brand new engine in about 55,000 miles
Customer: replied 10 months ago.
Ive checked all fuses...they are all good.
Customer: replied 10 months ago.
Can we talk on phone?
Expert:  HDGENE replied 10 months ago.

Ok, the distributor sends an rpm signal to fire both the coil and the injectors, if your not getting an rpm signal from the distributor it wont run. Verify the check engine light turns on when the key is turned to on

Customer: replied 10 months ago.
Check engine light does come on when key is on.
Expert:  HDGENE replied 10 months ago.

Ok have you checked for diagnostic trouble codes? Connected everything properly if you had to replace the battery since it sat?

Customer: replied 10 months ago.
I do not have a code tester. Yes battery has been replaced
Expert:  HDGENE replied 10 months ago.

You can check for codes without a scan tool, jump the aldl connector as mentioned below, its under the steering column dash area

READING DIAGNOSTIC TROUBLE CODES:
The means of communicating with the control module is the Data Link Connector (DLC) located under the instrument panel and is sometimes covered by a plastic cover labeled "DIAGNOSTIC CONNECTOR." The DLC is used in the assembly plant to receive engine information to determine proper operation before it leaves the plant. The Diagnostic Trouble Codes (DTC's) stored in the control module memory can be displayed by counting the number of flashes of the Malfunction Indicator Lamp (MIL) (Service Engine Soon) when the diagnostic terminal of the DLC is grounded. The DLC terminal "B" (diagnostic terminal) is the second terminal from the right of the DLC top row. The terminal is most easily grounded by connecting it to terminal "A" (internal control module ground), which is located to the right of terminal "B" on the top row of the DLC.

When terminals "A" and "B" have been connected, the ignition switch must be turned to the "ON" position with the engine NOT operating. The MIL (Service Engine Soon) should flash DTC 12 three times consecutively. This would be the following flash sequence: One flash, pause, two flashes, long pause, one flash, pause, two flashes, long pause, one flash, pause, two flashes. DTC 12 indicates that thecontrol module diagnostic system is operating properly. If DTC 12 is NOT indicated, a fault is present within the diagnostic system itself, and should be addressed by consulting the appropriate diagnostic chart.

Following the output of DTC 12, the MIL will indicate any DTC three times consecutively. However if no other codes are present will continue to repeat DTC 12. If more than one diagnostic trouble code has been stored in the control module memory, the DTC's will be displayed from the lowest to the highest with each DTC being displayed three times.

DIAGNOSTIC MODE:
When the diagnostic terminal is grounded with the ignition "ON" and the engine "OFF," the system will enter the diagnostic mode. In this mode, the control module will:

  • Display a Diagnostic Trouble Code (DTC) 12 by flashing the Malfunction Indicator Lamp (MIL) "Service Engine Soon" (indicating that the system is operating properly).
  • Display any stored DTC's by flashing the Malfunction Indicator Lamp (MIL) "Service Engine Soon." Each DTC will be flashed three times, then DTC will be flashed again.
  • Energize all control module controlled relays and solenoids except the fuel pump relay. This allows checking circuits which may be difficult to energize without driving the vehicle and being under particular operating conditions.
  • Move the Idle Air Control (IAC) valve to its fully extended position on most models, blocking the idle air passage. This is useful in checking the minimum idle speed.

FIELD SERVICE MODE:
If the diagnostic terminal is grounded with the engine running, the system will enter the "Field Service" mode.

In this mode, the MIL "SERVICE ENGINE SOON" light will indicate whether the system is in OPEN or CLOSED LOOP operation.

If the system is in OPEN LOOP operation, the light will flash approximately two and one-half times per second.

CLOSED LOOP operation is indicated by the light flashing approximately once per second. Also, in "CLOSED LOOP" the light will stay "OFF" most of the time if the system is running lean. It will stay "ON" most of the time if the system is running rich.

While the system is in the "Field Service" mode, new codes cannot be stored in the control module and the "CLOSED LOOP" timer is bypassed.

Customer: replied 10 months ago.
This will take some time to do. How can I reach you for cut her questions
Customer: replied 10 months ago.
Futher questions
Expert:  HDGENE replied 10 months ago.

Yes, just respond back to this question when you need more help. Im in arizona on PST. On here daily 2pm PST and most of the weekend after 10am pst

Customer: replied 10 months ago.
Okay. It will be tomorrow
Expert:  HDGENE replied 10 months ago.

No problem, ill be here after 10am PST

Expert:  HDGENE replied 10 months ago.

Hello, do you need more help with this concern?

Expert:  HDGENE replied 10 months ago.

Hi, do you need more help with this concern?

Expert:  HDGENE replied 10 months ago.

Hello, the question remains open until it is rated, do you need more help with this concern>

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