99 Tahoe 5.7L Starting Problem

[AtekorSFR]

1999 Tahoe 5.7L, 350k miles, SFI

The truck sat all weekend, went to start it on Monday and it would not start. It sounds like it wants to start but nothing. I could smell fuel. I search the net and the threads here. So I checked the fuel pressure It is at 60lbs. Was thinking the crank sensor, but it does want to start. The security light blinks and goes out.

Gave up for a few days. Then tried to start it, it started but barely ran for a few seconds then died. Never got to full idle.

I was thinking about the TPS? Yes or No? Thinking about the Coil? Yes or No? Is there anything else I could check?

I haven't done any maintenance for months, was going to change the oil but this problem cropped up.

Any suggestions would help.

 

[AtekorSFR]

So, I took out the coil and tested it. 1 test did not show anything, one showed within range and the third was out of range. I replaced it and it started, it was rough but running pretty good right now. It did get flooded when it did not start before, that right now is what I am contributing to the initial start. Tomorrow I will see if it back to it's normal self.

What a pain to change the coil, your suppose to drill out the rivets, huh, yea if you take out the air conditioning at the firewall. I used a dremmel and to cut most of it and hit them with a chisel. Then pried the coil out.

By the way, I found out how to test the coil on the autozone web site for my truck.

 

[Conley79]

Is the security light flashing?

 

[lesterl]

Check the coolant temp sensor near the thermostat housing. It could have opened up and be telling the PCM to dump fuel in (open it would think -40 temps)

 

[AtekorSFR]

The truck would not start this morning, was firing but no go.
The security is ok, it flashes 3 times when the key is turned on then goes out.
I will check the temp sensor later today when I have a chance.
While reviewing threads someone stated that a cold start would not happen unless it had 65 psi on the fuel, is that correct? I have 60 psi.
What made me think of the coil was when I tested the spark, it appeared to have yellow in it. The cap was new last year when I did a tune up with new plugs, wires, cap, and rotor.

Is there a way to test the cap and/or rotor?
I am still searching for possibilities, what about the pick up coil? I read it is under the distributor cap? Easy to get to? Is there a way to test it?
I don't have the money to keep throwing parts at it.

 

[AtekorSFR]

So here I am throwing money at my Tahoe. For 15.00 I bought a Temp sensor (CTS) for it. It did not work.

I know that there is a pickup under the distributor cap and there is something next to the coil.

How do I test these items? I would have not bought a CTS except that I could not find a clear way to test the sensor.

When I tested spark plug 1, it had some orange. It fires but does not start.

Is there a way to test the cap with a multimeter? Is there a way to test the pickups in the cap with a multimeter? Is there a way to test the module next to the module next to the coil with a multimeter?

This is our second vehicle to go to work, any help would be desired. What I have to do is take them to work at 5 am then take my Grandson to therepy later, then pick them up, ugh, any help is appreciated.

The security go off after about 10 seconds, not that. Replaced the ignition coil, not that. Replaced the CTS at the Thermostat, not that. HELP!

 

[lesterl]

I said check, if you don't know how to test something, ask. A simple ohm check of the sensor with an ohmmeter would tell you if it was bad.

That being said, if you replaced it (the two wire one near the thermostat), I would check the MAF sensor (unplug the electrical wire to the MAF) and try cranking, I have seen several of these bad lately.....

The Module near the coil just fires the coil. If you suspect your cap and rotor are bad, pull a plug and insert into a wire and have someone crank with the plug sitting on the block. You might ohm out the coil wire to the "distributor"

1999 Vortec does NOT have a pickup coil. There is a crank sensor in the bottom of the timing cover and a cam sensor in the "distributor".

You can ohm out the contacts in the cap If you want, probably not gonna tell you much as it could be arcing internally.

 

[AtekorSFR]

OK, so I previously read a post on the MAF sensor and did that initially and it did not make a difference. Later today I will pull the #1 plug and check it.

When this all started, the truck was driven home on Friday and would not start on Monday. After I replaced the coil I did get it started, and started it a few times. It was warmer on that day. It did start hard, but after a few starts it was starting fine. Then it did not start again after that.

If I can afford it, would renting a scan tool that reads live data help for when I am trying to start the truck?

 

[lesterl]

When starting a live data scantool wont help as it has to connect after cranking and that takes a few seconds. If you could get it started, then perhaps it would help as you could read the fuel trims (big negative numbers indicates raw/unburnt fuel, positive is the PCM adding fuel.)

Do you have any Codes stored?

 

[munkee]

Fix?

Did you ever track this issue down. I am having the exact same problem. Changed the fuel pump, filter, and relay. Same thing, fires once then wont start. Same starting situation as well. Left it on a Friday and wouldn't start monday morning. Let me know if you have come across the fix or close.

Thanks

 

[lesterl]

Will it start with some carb cleaner into the intake?