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1998 Chevy K2500 Fuel Pump issues

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mindset

10+ Year Contributor
1,853
7
Jan 3, 2009
Brunswick, Ohio
First things first I went to a Chevy forum, go figure no help. I outta go to my DSM boys.

Here's the deal:

I am having a ton of trouble with this truck. 5.7L k2500 automatic. Last summer, the truck got a high idle, around 2200 RPMs. I never had time or the tools to fix it as I am in school and I only drove it to work. On a weekend that I happened to travel home, I got caught in a traffic jam and I believe the transmission overheated and the torque converter was slightly damaged because I was laying on the brakes while it wanted to maintain 2200 RPMs.

Once the transmission heated up to normal temps, driving on the highway, it would downshift to 4th as if the power wasn't getting to the wheels in overdrive.
Please note, this transmission failure occurred during the time of the high idle. The high idle is still a present issue with the truck.

So I picked up another truck for the time being and towed my Chevy back home to avoid more damage to the torque converter. However, in Columbus (location of school), the truck wouldn't start to drive it up on the trailer. I got a can of starter fluid and drove it up the trailer that way. I didn't really have a choice as keeping a vehicle on city streets near campus requires a parking pass and it was towards expiration and end of the school year. I didn't want to deal with 2 vehicles in Columbus as well.

A couple weeks later I make it home and I take a look. No start. Engine turns over. I cannot hear the fuel pump. I ended up replacing the rusty tank and the fuel pump. Go to turn it over and it starts right up (don't forget its still idling high). I drive it around a bit and pull it back into the drive. Good to go, issue one down.

My father calls me a couple days later saying the truck won't start. Long story short he tows it to the shop because I don't have the time and/or money to keep driving back and forth from school to home. He tells me later on that the shop claims the new fuel pump we installed was bad. My father explained how it was probably a bad connection to the pump; but, he bites the bullet and tells them to install a new pump.

Today, my father explained how the shop installed a pump. The truck started right up. They shut it off. They go to start it again and it doesn't start. He said they even "spliced" the connections better... replaced the fuel line... and the same results... they even put in another fuel pump assembly (total of 3 new assemblies). Fortunately, they didn't charge my father, but they said they couldn't fix it.

Does anyone have a clue what's wrong with it? I have a feeling it's not worth it to invest more money into it... any idea would be great.
I have a feeling it could be an ECU issue.
 
Swap the fuel pump relay with another in the fuse block. Usually the a/c relay or day time running lamps have the same relay. Are you positive it does not have fuel pressure? If you can check the pressure. That style of fuel inctecton requires around 59 psi to open up the popet valves. Also check the fuel pump ground there will be one right below the drivers door on the frame. Also check the ground on the frame behind the front bumper on the drivers side. Also there is a ground on the back of the cylinder heads that can give you trouble. Also check to make sure its not going into theft mode. I am a G.M. Master tech and will try to help you as much as possible.
 
My buddy fries pumps like no tommorow on his chevy, these year models are notorious for this.

First thing, behind your throttle body, is a shcrader valve (looks like an air inlet on a tire) you need t test the fuel pressure in the morning and see what it primes to. I can't remember the #s ATM. To test the pump, make sure there are no crimps in the fuel lines.

To your wiring issue is what I'm led to believe is the problem. Now, I'm not the best with a multi meter, but you need to find the correct ohms/amps upon key on. Make sure your ground strap (there's a few on under your bed) are good. Now, if your prime, voltage, and lines are good. You need to look into that stupid SPIDER-POPPIT fuel injected bullshit. The plug will rot, the lines will leak dumping gas everywhere under that intake.

On another note-- I am not a fan of these year trucks because I constantly work on them.

Swap the fuel pump relay with another in the fuse block. Usually the a/c relay or day time running lamps have the same relay. Are you positive it does not have fuel pressure? If you can check the pressure. That style of fuel inctecton requires around 59 psi to open up the popet valves. Also check the fuel pump ground there will be one right below the drivers door on the frame. Also check the ground on the frame behind the front bumper on the drivers side. Also there is a ground on the back of the cylinder heads that can give you trouble. Also check to make sure its not going into theft mode. I am a G.M. Master tech and will try to help you as much as possible.

Hello master tech! I've beat my head against it too much :)

Theft mode is a viable option. But wouldn't that kill spark??
 
This security system kills the fuel injection system.


1998 Chevy Truck K 2500 Truck 4WD V8-5.7L VIN R
Vehicle#»#Accessories and Optional Equipment#»#Antitheft and Alarm Systems#»#Description and Operation#»#Vehicle Theft Deterrent (VTD)#»#General Description
GENERAL DESCRIPTION
PASSLOCK(TM) SYSTEM
The design of the Passlock(TM) system is to prevent vehicle theft by disabling the engine unless the Passlock(TM) lock cylinder rotates properly by engaging the correct ignition key. The system is similar in concept to the passkey system. However, the Passlock(TM) eliminates the need for a key mounted resistor pellet. The components of the system are as follows:
The ignition lock cylinder
The ignition switch
The Passlock(TM) sensor
The EVO/Passlock(TM) module
The security indicator
The vehicle/powertrain control module (VCM/PCM)
IGNITION LOCK CYLINDER AND HOUSING
The ignition lock cylinder is located at the upper right side of the steering column. The Passlock(TM) sensor is in the steering column. The Passlock(TM) sensor is separate from the key and lock cylinder. The key and the lock cylinder work together in order to determine if the proper ignition key was used to start the vehicle.

In the event of an open Class 2 serial data line between the EVO/Passlock(TM) Module and the VCM/PCM, the vehicle will become fail-enabled if the VCM/PCM has already received the password from the EVO/Passlock(TM) Module for that ignition cycle (the engine is running). In this event, the following conditions occur:
The security telltale will be ON continuously.
The VCM/PCM will become tail-enabled for future ignition cycles.
If a failure in the Class 2 serial data line occurs before the ignition cycle, when the VCM/PCM is not fail-enabled, the following conditions occur:
The VCM/PCM will never receive a valid password in order to enable the fuel injectors.
The vehicle will not start.
IGNITION SWITCH
The lock cylinder and the visible key insert portion of the ignition switch are located at the upper right side of the steering column. The electrical switching portion of the assembly is separate from the key and lock cylinder. The electrical switch portion is hidden inside the steering column. The electrical switch portion and the key and lock cylinder synchronize and work in conjunction through the action of the mechanical assembly between the 2 parts.

PASSLOCK(TM) SENSOR
The Passlock(TM) sensor is inside the upper right side of the steering column. The Passlock(TM) sensor contains 2 hall effect sensors. The tamper hall effect sensor is on the top. The security hall effect sensor is under the tamper hall effect sensor. Both of the hall effect sensors monitor the magnet of the lock cylinder through an opening. The tamper hall effect sensor is physically placed on top of the security hall effect sensor. The placement enables the tamper hall effect sensor to engage first if an intruder attempts to bypass the Passlock(TM) sensor by placing a large magnet around that area of the steering column. There is a tamper resistor inside the Passlock(TM) sensor in order to help prevent tamper to the system. Passlock(TM) equipped vehicles have a selection of 10 different security resistors ranging up to 13 k ohms . Install any of the security resistors inside the Passlock(TM) Sensor in order to generate a unique Passlock(TM) code. All 10 combinations of the Passlock(TM) sensor have the same part number. However, you cannot simply replace the Passlock(TM) sensor and expect the system to operate properly. Always start by performing the Diagnostic System Check first and following the instructions.

EVO/PASSLOCK(TM) MODULE
The EVO/Passlock(TM) module contains the theft deterrent system logic. The EVO/Passlock(TM) module reads the Passlock(TM) data from the Passlock(TM) sensor. If the Passlock(TM) data is correct, the EVO/Passlock(TM) module will pass theft. The EVO/Passlock(TM) module will then transmit the code password to the VCM/PCM. During the tamper mode the vehicle may start. The vehicle will quickly stall. If the EVO/Passlock(TM) module receives the wrong Passlock(TM) data, the VTD will immediately go into the tamper mode. The tamper mode will lock-out the vehicle fuel injectors for 10 minutes . The SECURITY indicator will flash while the VTD is in the tamper mode.

If the passlock sensor sends a correct password to the EVO/Passlock module when the ignition is in the ON position, the EVO/Passlock module will send a fuel enable signal to the VCM/PCM. The VCM/PCM will not disable the fuel due to any EVO/Passlock module message for the remainder of the ignition cycle.

SECURITY INDICATOR
The SECURITY indicator is on the instrument cluster. If the SECURITY indicator flashes or if the SECURITY indicator lights continuously during the vehicle operation, Refer to A Diagnostic System Check - Theft Deterrent . See: Testing and Inspection

VEHICLE/POWERTRAIN CONTROL MODULE
The VCM/PCM communicates with the EVO/Passlock Module over the Class 2 serial data line. When the EVO/Passlock(TM) Module determines a no start condition it sends a Class 2 serial data password to the VCM/PCM in order to disable the fuel injection system. If the EVO/Passlock(TM) Module receives the expected voltage from the Passlock(TM) sensor, the EVO/Passlock(TM) Module sends a Class 2 serial data password to the VCM/PCM in order to enable the fuel injection system. The VCM/PCM then allows the vehicle to start correctly. It the Class 2 serial data password from the EVO/Passlock(TM) Module to the VCM/PCM is not within the Vehicle Security Status Message, the fuel injectors will shut OFF during a star attempt. The SECURITY telltale will be ON STEADY for approximately 10 minutes and then turns OFF. If the VCM/PCM does not receive the same password from the EVO/Passlock(TM) Module as the last learned one, the vehicle will start and quickly stalls due to the Fuel Lockout.

CHANGING THE PASSLOCK(TM) COMPONENTS
The design of the Passlock(TM) system is to prevent theft even if the various theft deterrent parts change. The parts that can no longer be changed without the possibility of going into a tamper mode are:
The Passlock(TM) sensor
The EVO/Passlock(TM) module
The VCM/PCM
If you replace any of these parts the vehicle may start and stall for 10 minutes . This is the long tamper mode. If this occurs, the system must go through a long tamper mode cycle. During this time the SECURITY indicator will be flashing for the full 10 minutes and the DTC B3031 will be set. The EVO/Passlock(TM) module and the VCM/PCM require the full 10 minutes in order to complete a learn cycle. The ignition switch must remain in the RUN position until the SECURITY indicator stops flashing. You will need to repeat the cycle if the ignition switch does not remain in the RUN position. When replacing any of the above parts it is recommended to perform one of the following procedures:
Seed and Key Procedure. Refer to PASSLOCK Reprogramming Seed and Key . See: Service and Repair
Auto Learn Procedure. Refer to PASSLOCK Reprogramming Auto Learn . See: Service and Repair












Were were both thinking the same thing though. Lol
 
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Ok guys I have some new information and my initial story may not be accurate. So I gave my father a call to better recollect the issues. Here's what we composed.

Before the battery died and was replaced I had a GM mechanic use his diagnostic tester and got the following codes below in order of importance. Im not sure if any of this is related to it not starting.
CHECK ENGINE LIGHT
BELOW ARE THE TROUBLE CODES BEFORE I CHANGED THE BATTERY


P0101 Mass Airflow Sensor Performance Last Test Failed

P0102 Mass Airflow Sensor Circuit Low frequency Last Test Failed

P0461 Fuel Level Sensor Performance Last Test Failed

P0507 Idle Speed High

P0730 Incorrect Gear Ratio

P1509 Idle Speed High - IAC System Not Responding

P1810 TFP Valve Position Switch Circuit Malfunction

P1870 Transmission Component Slipping

I took it to a repair shop to get it running. They tested the fuel pump and put a pressure gauge on it and it tested 20 PSI. (well below what is needed to start) They also checked the volts to the fuel pump and it was 12v and the pressure did not drop off right away held pretty constant indicating there probably wasn't a leak in the line or injectors. They put a new fuel pump in with new wiring and checked the ground and it still wouldn't start and the pressure was still at 20 PSI along with the other same readings. They then tested the pressure in the return line with an inline guage and it started right up reading 60 to 65 PSI. They shut it off and replaced the return line thinking that was it. When they tried to start it again it wouldnt start again. They went through the same process and replaced the fuel pump again (Delphi) getting the same readings 20 PSI and could not get it started again. They tried to duplicate the same things that got it started the one time before but were unsuccessful.
 
If they tossed two fuel pumps OEM and the voltage is right, I doubt that's your issue, it's very rare a actual fuel line gets stopped up. (I have fixed these even when someone crunched EGGS into the gas tank.) I would be very concerned with the MAF sensor. If it's saying it's low voltage than it's not reading the proper airflow to tell the computer what to feed the gas.

You can find GM MAFs everywhere. Or buy a reman from your local parts store, see if that works, if not, return it.

I wouldn't be worried about fuel at the return line. The schrader valve behind the throttle body would tell you exactly what the PSI to the engine is. If it's 20, I'm not understanding, I have never put in a direct OEM replacement and had an issue. Make sure that, that fuel pump box doesn't say AIRTEX that the are calling Dephi. Get you some brake parts cleaner (it's cheaper than carb cleaner) and pull the breather top off the TB and spray the shit out of it on the first start up and see what it does, if it fires, it's a fueling issue.


Good luck
 
For the low fuel pressure I would make sure the pump is the correct part number for the truck. If you are positive it is and its not an airtex as stated by dsmbanditfz76 I would replace the fuel filter and flush the fuel lines since you had a rust problem. I would also inspect/replace the fuel pressure regulator. The fuel pressure regulator is located under the plastic part of the intake manifold on the fuel injector "spider". The p0101 and p0102 with the high idle would indicate you have a vacuum leak. Some times a dirty maf could set these codes. A bad map sensor can set those codes also. Basically the computer uses the map sensor and maf sensor to check each other. You can check to see if your maf is bad by unplugging the maf and looking at the fuel trims. If the go down to normal (plus or minus 7 combined) then you have a maf problem. Judging by the high idle I would lean more of a bad vacuum leak.






Also load test the 12v power and the ground circuits to the fuel pump. You can show you have 12v and a good ground with a volt meter and have high resistance in the circuit. We use a headlamp in the shop to load test. If it lights up bright then they are good. Also have you swapped/replaced the fuel pump relay?
 
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I have also seen the spider lines leak, causing gas to not make it to the POPPIT and dumping to much in one and not enough of the other.

Again, I am not a fan of this setup. Ford already had real FI from 95-99 :D
 
Ok guys, thanks for the information. Once I get a chance to head back home and look at the truck some more I will update this thread. I'm currently debating what to do with it as I read money signs reading your replies... but, I plan to do some testing.

Any more ideas that you guys get let me know! Thanks.

Any chance this could be an ECU issue? What about the oil pressure switch?

According to my father, the shop did replace the line and they said the relay tested "good".
 
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