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Author Topic: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.  (Read 2031 times)

Offline billr

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #30 on: October 27, 2013, 08:10:40 PM »
If there is suspicion that it is flooding, disconnect power to the fuel pump by pulling a fuse/relay or disconnecting the harness to it.  Pull the plugs, or as many as are easy to do, and crank the engine for several seconds to "air it out".  Make sure the plugs are dry and put them back in.  Now, with fuel still disabled, try cranking after a quick blast of carb-cleaner or staring-fluid into the intake.  If it fires briefly like that, you will have confirmed the spark is OK, no need to fuss with that more, and that the engine probably is flooding.  If you don't want to bother removing the plugs, you could try just cranking several times for 5 seconds or so each time and with a wait of a minute or so between crankings to let the starter cool.  Done with the fuel pump still off, of course.  Or just let the engine sit overnight, fuel-fouled plugs will usually dry out after a few hours.  It is quicker and more certain to pull the plugs though...

Offline Blkcat

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #31 on: October 27, 2013, 08:27:16 PM »
Redid the pressure test (Previous results were someone else looking at the dial, not me, wont make that mistake again.)

Peak pressure was 58 psi, and it took just over one minute for it to drop below 50psi.

Offline Mobile Dan

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #32 on: October 27, 2013, 08:42:25 PM »
I would recommend further attempts to start your (apparently) flooded engine. Removing the fuel pump relay might be a good first step, as long as that doesn't also disable the ignition system (Make sure you still have spark if relay is removed).

You first said "About two weeks ago, it died on me." Could you expand that, because there may be missing details that might be helpful.
« Last Edit: October 27, 2013, 08:43:07 PM by Mobile Dan »

Offline Blkcat

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #33 on: October 27, 2013, 09:01:37 PM »
I had picked up the truck aprox 7:30pm, it had not been driven for two days before that. I drove to a friends home, maybe half a mile away. Sat there and talked to him for 5-10 minutes, truck in park but running, then drove about another 100-150 yards, turned a left hand corner, the engine sputtered once, like it was running out of gas, and then died. I tried to start it, but nothing. The gas gauge that is in it is hardly accurate once it gets under 1/4 tank of gas, so I assumed that I ran it out of gas. Went to gas station and got a gallon of gas, put it in the tank, tried to start it again, nothing. Friend of mine stopped by, tried to help me, said he couldnt hear the fuel pump running.

Next day, I got the truck towed back to my house by a friend, and let it sit there, as I didnt have the money right then to go out and buy a fuel pump. Friday I bought a fuel pump and fuel filter, figuring I would be doing that on Sat. I have been studying up on fuel pump replacement over the last two weeks, so felt fairly sure I could do it. Just for kicks, I tried to start the truck Friday night, and heard the fuel pump kick in for about 2-3 sec, then kick back off. Key was in the on, but not start position. Either my friend was mistaken about not hearing the pump, it was a noisy street, or the pump just decided to start working again, I figured on option A. Started doing some more research into the fuel system, bought a OBD2 reader and a fuel pressure gauge. Found the fuel pressure port and hooked the gauge up. Had a marginally more mechanicly inclined than I friend check the gauge while I turned the ignition. He read off the psi as 60 and holding. I then hooked the OBD2 reader to the port under the dash, hit the read button, it scanned for about 5-10 seconds, and came back with 0 Codes. I checked the Haynes manual for fuel pressure, it said 55-62 (within pressure), and thats when I turned to this site.
« Last Edit: October 27, 2013, 09:12:22 PM by Blkcat »

Offline Blkcat

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #34 on: October 27, 2013, 09:49:26 PM »
Seeing as we are back to square one (sorry about that) I guess I should give you my skill level as well. My father was a great DIY mechanic (rebuilt his 351C Mustang engine many times and restored a '67 Ranchero) but a crappy teacher. I've done my own brakes a few times, changed out a couple alternator's, assisted him with replacing transmissions. I know most of the tools, if not always the technical names for them. As an adult, most of my repair work has been done by a shop, as my wife's father worked for GM and we got good deals on parts and labor through GM dealerships. This is my first truck, and it was bought used about 10 months ago from a friend who owns a dealership. I bought it for towing and for camping. My father's DIY streak ran true in me, if it developed late, so I dont really wanna take it in to be fixed, I wanna learn to fix it myself.

Offline Mobile Dan

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #35 on: October 27, 2013, 09:54:52 PM »
My best guesses would be....Timing chain worn and "jumped out of time", causing loss of compression and spark happening too late, or, Coolant temperature sensor circuit open, computer thinks it's 40degrees below zero, causing engine flooding.

If it won't even try to run after some "de-flooding" attempts, a compression test and a timing light may be needed.

Keep your battery charged...I need to recharge mine so I'll be going to bed shortly.

Offline billr

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #36 on: October 27, 2013, 10:32:36 PM »
For sure, take compression during one of these plug inspections.  If you are going to be a DIYer, a compression gauge is one of the essentials; and I expect your dad already has a good one.

Offline Blkcat

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #37 on: October 27, 2013, 10:42:36 PM »
Father hasnt been around for a few years, and my mother wouldnt know a compression gauge from a tire gauge.

I will attempt the "de-flooding" tricks tomorrow and obtain a compression gauge from autozone.

Offline Blkcat

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #38 on: October 28, 2013, 03:06:19 PM »
ok, pulled the fuel pump relay and checked for spark, had.

Sprayed carb cleaner directly into the throttlebody, wife turned the key, and the engine turned over, not enough to start, but did turn over.

Online kev2

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #39 on: October 28, 2013, 04:04:38 PM »
  all this cranking - I would suggest out of an abundance of caution -  check the engine oil for evidence of FUEL...   

  confirm this is a 1999 5.7L  CSFI -  all the injectors inside manifold.... AND the fuel pressure is only 58psi? You said the 'code reader'  shows NO codes-  I would ask is the CEL on?  AND it does come on at every start@3seconds?   
 

Offline billr

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Re: 99 Tahoe 4x4 5.7 Vortec-Crank but wont start.
« Reply #40 on: October 28, 2013, 07:24:32 PM »
Okay, with the carb-cleaner it would fire and run very briefly, but wouldn't continue to run?  And, the fuel pump relay was out during this?  That would indicated spark, timing, compression, etc. is all OK and this is *just* a flooding problem.  Agreed, keep an eye on the engine oil.  The last thing you want to do is escalate this into a ruined engine problem!  Do you have a scan-tool or PC link that shows live-data?  It would be nice to know the ECT sensor hasn't failed such that the PCM thinks you are trying to start in a -40F ambient and setting a way, way-rich cranking pulse for the injectors.

 

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