General Motors Tech Chevy tech talk within.

98 k1500 fuel problems

  #1  
Old 02-05-2011, 05:01 PM
Beginner
Thread Starter
Join Date: Feb 2011
Location: S. NH
Posts: 23
Default 98 k1500 fuel problems

Hi I have a 98 k1500 that has a start -stall issue. When I start the truck it stalls immediately . I suspect the fuel pump but am not sold on it yet. The fuel pump is only a few months old , I have jumped out the fuel pump relay so the pump runs continuously and the truck still will not run, I installed a pressure gage on the test port and when the key is in the on position the pump has 64psi when the truck starts then dies it drops to 60 psi. If I pour fuel into the throttle plate the truck will run so I know it is a fuel issue, also when this is happening [pouring fuel ] the fuel pressure stays at 60 psi. Although when I turn the key off pressure drops right off . I have been told the pressure regulator might be the cause but I am not sold because if it were the regulator I believe when I had it hooked up direct the pressure would have climbed higher I believe. Also I have a flashing security light on , but it has been on and flashing since I have owned the truck 90,000 miles so I don't believe it to be the problem but maybe. any thoughts????
 
  #2  
Old 02-05-2011, 05:48 PM
Mr_Shamrock's Avatar
Chevrolet/GMC, Racing, Recreational Forum Moderator
Join Date: Apr 2009
Posts: 2,267
Default

The injectors are a known issue on these trucks. If your pressure is that high I think your pump may be good although the bleeding down really fast could be either a pump or regulator issue. Will the truck eventually run or does it stall all the time?
 
  #3  
Old 02-05-2011, 06:00 PM
Beginner
Thread Starter
Join Date: Feb 2011
Location: S. NH
Posts: 23
Default

The truck will not run at all, I just went out and tried to reset the security light but it is the same as it has always been. A little history this truck did this to me twice before and just mysteriously started after awhile, firstime I kept missing with it and where I was working a guy had a truck like mineand I used his fuel pump relay and it started, but then put mine back in and it still ran? 2nd time would not start had it towed to the dealer and the mechanics were on lunch they told me to go get something to eat because everyone was at lunch, I came back an hour later the truck was out parked in the street, asked what they found and they said the mechanic came back from lunch and needed to move it , never looked at it just jumped in it and started it up and put it in the street, couldn't replicate the problem
 
  #4  
Old 02-05-2011, 08:29 PM
Beginner
Thread Starter
Join Date: Feb 2011
Location: S. NH
Posts: 23
Default

Originally Posted by Mr_Shamrock View Post
The injectors are a known issue on these trucks. If your pressure is that high I think your pump may be good although the bleeding down really fast could be either a pump or regulator issue. Will the truck eventually run or does it stall all the time?
will not run at all
 
  #5  
Old 02-06-2011, 03:46 PM
Beginner
Thread Starter
Join Date: Feb 2011
Location: S. NH
Posts: 23
Default

Well I'm disgusted now spent all day laying on my back pulling the fuel tank to replace the fuel pump to no avail the truck is still doing the same thing starts and shuts right off. Is there any way known to completely bypass the passlock system? mine flashes but it has for 3 yrs I just want to bypass it altogether.
 
  #6  
Old 02-06-2011, 04:32 PM
Mr_Shamrock's Avatar
Chevrolet/GMC, Racing, Recreational Forum Moderator
Join Date: Apr 2009
Posts: 2,267
Default

Try this:

PASSLOCK

The Passlock system is designed to prevent vehicle operation if the key is not used to start the vehicle. The key, which does not contain a resistor will turn the Passlock lock cylinder. The Passlock lock cylinder will relay a resistance code to the instrument panel cluster (IPC). It does this by rotating a magnet past a stationary hall effect sensor, creating a resistance code. At this point the IPC will determine if the resistance code is correct and within an acceptable time frame. If the code is correct, the IPC will send a coded password to the powertrain control module (PCM). If the PCM receives the correct password, it will allow the fuel injectors to operate normally and the vehicle will start and run normally. If the correct resistance code from the lock cylinder is not received within the acceptable time frame, the vehicle will go into a short tamper mode during which the theft deterrent system will not allow the vehicle to operate for approximately 4 seconds. When this occurs, the security indicator will flash. After three consecutive failed tries, the system will enter into a long tamper mode. In this mode, the fuel injectors will be disabled for approximately 10 minutes, and the security indicator will be flashing. Please note that in any of the tamper modes, the vehicle may start, but it will quickly stall.

Default
The Passlock system is designed to prevent vehicle theft even if any of the theft deterrent parts are replaced. Passlock eliminates the need for the key mounted resistor. Parts that can no longer be replaced without the possibility of the system going into a tamper mode and prevent starting are: the lock cylinder, the instrument panel cluster (IPC), and the powertrain control module (PCM).

In order to initiate the relearn:

1. Hook up your scan tool to erase any of the passlock/vehicle theft deterrent trouble codes. If there are any other codes, note them before you erase them, so you may address them after the relearn has been completed.
2. With the ignition key in the “On” position from the code-clearing step, attempt to start the vehicle. At this point, if the vehicle starts, and the security light has not illuminated, a relearn is not necessary, and you’re done. If the vehicle starts and stalls, leave the key in the “Run” position and wait for the “Security” light to turn off. This will take approximately 10 minutes. At any time during this relearn, the light may flash or be on steady. If the ignition switch is turned off at any time during this relearn cycle that the security light is illuminated, the entire cycle must be restarted from the beginning. For most cars, one cycle will be sufficient for the relearn. If the vehicle will not start after the first cycle, then continue the process from step #3 to the end. Most trucks will require that you continue from step #3 to the end.
3. When the light turns off, turn the ignition switch to the “Off” position for approximately ten seconds.
4. Next, repeat steps 2 and 3 two more times for a total of three cycles. After the third time, the new code will be relearned on the next start attempt when the ignition switch is rotated from the “Off” position.
5. From the “Off” position, start the vehicle, observing the security light. If the vehicle starts and runs normally, and the security light is off, the relearn is complete. If the vehicle does not start, check for trouble codes before proceeding further.
 
  #7  
Old 02-08-2011, 02:33 PM
Beginner
Thread Starter
Join Date: Feb 2011
Location: S. NH
Posts: 23
Default

Not sure what has actually transpired here on this truck, but I went out this morning to reset the security pass lock and the truck started when I started the procedure . Could be I had inadvertanly reset it while I had been testing different things with the key on multiple times at different times I don't know, but the security light is not flashing and the truck runs again. I hope this was the problem , and if it was when it happens again I will be able to fix it without costing me another 485.00 for a fuel pump. Thanks for the help
 
  #8  
Old 02-08-2011, 03:31 PM
Mr_Shamrock's Avatar
Chevrolet/GMC, Racing, Recreational Forum Moderator
Join Date: Apr 2009
Posts: 2,267
Default

Good deal - nothing like accidentally fixing something!
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Blake
Chevy Silverado/ GMC Sierra Forum
22
01-04-2019 05:26 PM
a.powell
Chevy Silverado/ GMC Sierra Forum
1
11-01-2011 07:11 PM
way5167
Chevy Silverado/ GMC Sierra Forum
2
08-09-2011 01:12 PM
Blake
Chevy Silverado/ GMC Sierra Forum
6
04-06-2011 11:13 PM
gijacob
General Motors Tech
10
08-19-2009 07:08 PM


Thread Tools
Search this Thread
Quick Reply: 98 k1500 fuel problems


Featured Sponsors
Vendor Directory

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.