1998 Tahoe 5.7 Usually wont start, but sometimes does

My 1998 Tahoe 5.7 2dr. 4x4 wont start. It turnsover, but wont start. Sometimes it will start fine and run fine with no problems. My fuel pump is new, fuel filter about 4 months old, new fuel pressure regulator, and tune-up. Where is the problem? Right now it hasnt started in three days, maybe tomorrow it will.

does it crank over? try pressing the accelorator a little and see what happens.. have yo checked for spark and fuel???

It cranks over, but doesnt start. I have tried pumping it, I have tried holding it down, and nothing ever happens. Today it started up again, but after 3 days of not starting. Im fixing to go to the store to get that tool to check for spark. Im pretty sure it is getting fuel, but how can I check just to be sure? fyi: I do hear the fuel pump turning on.

I've got a 97 and frequently had the same problem. after 3 fuel pumps i was finally told that at least with the 97 there was a problem with the pigtail coming off of the fuel pump. It was apparently shorting out. I replaced with an ACDelco replacement pigtail, and haven't had a problem since.

a easy way to check for gas is to try to start it and if it doesn't remove a spark plug and see if its wet with gas.

A common problem is corrosion in the vehicle electrical connector that connects to the fuel pump. You could be a victum of a mechanic that didn't bother to inspect the connector when replacing the fuel pump. Test fuel pump operation by putting an ammeter between the positive side of the battery and the fuel pump test port near the relay box in the engine compartment. You should get at least 6.5 amp reading on a good pump. Connect a fuel pressure guage to the fuel line port (on top of the fuel line near where it enters the fuel pressure regulator. You should have 60 plus PSI when testing with the engine stopped. You won't start if it is 50 PSI. You can usually get a vehicle with low fuel pressure started using ether based starting fluid.

I'm having the same problem with mine it quit 5 days ago going down the road. Hasn't ran since. It's getting gas up to the motor it just isn't injecting it. Can't figure out whats wrong.

I can pour gas straight into the intake and it will crank, but i can't figure out why it isn't injecting gas. If anyone has any suggestions let me know.

I have a 98 Tahoe in my shop now with similar issues. The entire fuel system is new and has all new wires for the pump, sending unit, and pressure sensor. It has just under 60 PSI at the fuel rail and my scan tool says everything is working fine. The only reason it won't start is because of the security feature prohibiting it (VTD). The injectors are getting the +12V they need, but the ECU just won't pulse the ground needed to operate them. I've been trying to find info on this security feature and how to "reset" it. GM says to put the key in the ignition and turn it on and let it sit for 10 minutes. That didn't work. I re-programmed the keyless entry remote and that didn't work either. Another GM dealership said that there is no way to reset it and that there is probably something wrong with the Passlock security feature. You guys might be having a different issue because fuel issues are common on Suburbans/Yukons/Tahoes, but the 98 Tahoe in my shop won't start because of the security feature. If anyone has any info or diagrams of the VTD system please PM or email me with the info. Thanks in advance for any help.

well my problem ended up being an evil possessed fuel pump. it seems that everytime I checked the fuel pump, it would work and start. then I would move on, and the little humming pump wouldnt pump anymore, UNTIL i checked it again. had to replace it again, good thing for warranties.

Replaced the fuel pump in my cousin's 97 for the third time this weekend. Although a bad pump was not the cause of the pump not pumping. He does have a problem with the wiring, although its not corrosion. Still have to figure it out, but on his '97, he can reach in through the drivers side rear wheel well and grab the wires on top of the tank. He is able to get the pump to run if he messes with the wires.

I have replaced the fuel pump twice in my '97. Second time I found the connector was bad. What it seemed to me was the connector gets hot. It was slightly melted and one of the pins on the new pump burned. A new connector and a second pump fixed the problem. GM refused to warrenty the pump because I put it in.

I have a 98 Tahoe in my shop now with similar issues. The entire fuel system is new and has all new wires for the pump, sending unit, and pressure sensor. It has just under 60 PSI at the fuel rail and my scan tool says everything is working fine. The only reason it won't start is because of the security feature prohibiting it (VTD). The injectors are getting the +12V they need, but the ECU just won't pulse the ground needed to operate them. I've been trying to find info on this security feature and how to "reset" it. GM says to put the key in the ignition and turn it on and let it sit for 10 minutes. That didn't work. I re-programmed the keyless entry remote and that didn't work either. Another GM dealership said that there is no way to reset it and that there is probably something wrong with the Passlock security feature. You guys might be having a different issue because fuel issues are common on Suburbans/Yukons/Tahoes, but the 98 Tahoe in my shop won't start because of the security feature. If anyone has any info or diagrams of the VTD system please PM or email me with the info. Thanks in advance for any help.

Your issue defintely sounds like the Passlock has gone bad, which they have been known to do. I've got a 98 and I have been lucky that the Passlock system has only shut the fuel pump off about 5 times and I know what not to do....tu8rn the ignition so ast it dioesn't have time to recognize the key!

This post is old and you may have already fixed the issue, if not reply I've got schems, etc.

Probably the idle air control. They just redesigned the whole throttle body for Tahoes and I know you can retrofit this new design onto at least '02 so I assume earlier.

happend again. i now know its electrical. my pump sometimes doesnt get power. im going to be going over the electrical stuff tmrw. im tired of this sh*t! i want to fix it once and for all. i almost got the dealership to do it, but damn, they are crazy as joe rogan.

Guide lines for hard to start.
First check for spark to spark plugs at 2 or more plugs.
Then check for proper fuel pressure.
If spark and good fuel pressure then move on to injector pulse check.
Also if you have spark feed it a little carb cleaner not starting fluid and see if it will run.
On the fuel pressure check.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Most Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Even 1 or 2 lbs low will give a no start.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.
MT

happend again. i now know its electrical. my pump sometimes doesnt get power. im going to be going over the electrical stuff tmrw. im tired of this sh*t! i want to fix it once and for all. i almost got the dealership to do it, but damn, they are crazy as joe rogan.
First check for spark to spark plugs.
If you have spark to plugs then jumper the fuel pump prime conection or see if it has 12 volts on it when no start.
If jumpered or it has 12 volts on it the fuel pump should run.
Mt

where's the fuel pump prime connection?

just saw this old post. i'll try to find the fuel prime connection and try jumping it and check voltage.
thanks MT-2500

well i was gonna check the voltage, but when i went to start my tahoe, it started, so i turned it off, unplugged what i thought was the prime connector, to make sure that was it, i checked if it would start (which it shouldnt), but it did. so i guess i dont know where the prime connector is. but my tahoe started over and over again with no problems. fuel pump kicked on everytime. i dont wanna drive it, till i find out whats going on.:screwy:

mine was doing something similar. i found out it was the battery connection. gm used 2 connectors on the battery terminal. the conct area between the 2 becomes corroded. i cleaned mine, put on some anti-corrosion gel, and put it back together. have not had a problem since. when i was reseaching for mine i found that it could also be the anti-theft device. if you need to bypass it, you can find out how on this site. do a search for "passlock bypass". good luck.

Your issue defintely sounds like the Passlock has gone bad, which they have been known to do. I've got a 98 and I have been lucky that the Passlock system has only shut the fuel pump off about 5 times and I know what not to do....tu8rn the ignition so ast it dioesn't have time to recognize the key!

This post is old and you may have already fixed the issue, if not reply I've got schems, etc.

I have a 99 tahoe with the same security problem, i have changed the passlock, key cylinder, pretty much everything in the security system except for the wiring itself. I am stumped completely, it turns over then shuts itself off and blinks security, i also have recently changed the fuel pump in the gas tank. Please help!!!

I have a 98 Tahoe in my shop now with similar issues. The entire fuel system is new and has all new wires for the pump, sending unit, and pressure sensor. It has just under 60 PSI at the fuel rail and my scan tool says everything is working fine. The only reason it won't start is because of the security feature prohibiting it (VTD). The injectors are getting the +12V they need, but the ECU just won't pulse the ground needed to operate them. I've been trying to find info on this security feature and how to "reset" it. GM says to put the key in the ignition and turn it on and let it sit for 10 minutes. That didn't work. I re-programmed the keyless entry remote and that didn't work either. Another GM dealership said that there is no way to reset it and that there is probably something wrong with the Passlock security feature. You guys might be having a different issue because fuel issues are common on Suburbans/Yukons/Tahoes, but the 98 Tahoe in my shop won't start because of the security feature. If anyone has any info or diagrams of the VTD system please PM or email me with the info. Thanks in advance for any help.

I've had a similar problem: Put the key in, crank it, it starts and with in a second it shuts off. Dealership replaced the sensor in the steering column and this fixed the problem. This sensor reads the key and matches it. The only way to get around this (untill you actually fix it) is to put your key in, crank it, let it start and die, now....without touching the key leave the key in the on position 3 minutes, then....turn it off for 1 minute, then....turn it back on for 3 minutes (without cranking the engine) then off for 1 minute and back on for 3 more (without cranking the engine)....This came from a friend that works at a GM dealership. Somewhere within those last 3 minutes the "Security" light in the dash should go out, and if it does it will start.http://www.automotiveforums.com/vbulletin/images/smilies/chair.gif

Check the fuel pressure and it might be a fuel pump agian and did you replace the fuel filter when you replaced the fuel pump?That is part of the warrenty of a fuel pump,replacing the fuel filter.The old fuel filter is full of dirt and trash that will ruin the fuel pump right awayThe fuel pressure specs are 60-66 psi and will not run under those specs.