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Author Topic: 87 p/u won't start  (Read 21225 times)

Offline Tjerica1201

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87 p/u won't start
« on: January 16, 2015, 01:01:38 pm »
Lookin for the diagnosis guys!!  My diagnosis knowledge is pretty primitive, my abilities are not.  Are there any guys out there are a little more intelligent on the matter.

Here's what it's doin. Turns over strong, I can see fuel sprayin out the injectors, I've grounded the #1 plug and it's hitting when I crank, I've shined a timing light on it and it's spot on.

I rebuilt the injectors and tbi a couple years ago. Newer plugs, wires, cap, rotor.

I know my way around a multimeter but have no idea what use it on to see what's goin on. 

Thanks
« Last Edit: February 04, 2015, 09:31:44 am by Tjerica1201 »
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Offline Neospartan

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Re: 87 p/u won't start
« Reply #1 on: January 16, 2015, 02:32:26 pm »
Could be a vaccum leak? Just a thought.
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Offline jaredts

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Re: 87 p/u won't start
« Reply #2 on: January 16, 2015, 03:07:16 pm »
Your diagnosis steps so far eliminate most every normal failure I can think of for an engine that was running previously.  Was this running previously with no issues, and then wouldn't start, or is this a recent rebuild of some kind?
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Offline Tjerica1201

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Re: 87 p/u won't start
« Reply #3 on: January 16, 2015, 04:26:01 pm »
It ran perfect prior to parking. I built it 5 yrs or so back. It's a 383.

As I went out today to work on it, it now will not roll over. It acts like it wants too but won't. Acts like its a really low battery. I hook jumpers to it and am getting 13 volts to it, same thing. Ideas?  I have replaced the starter wire and am getting zero ohms on the negative.
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Offline Tjerica1201

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Re: 87 p/u won't start
« Reply #4 on: January 16, 2015, 07:38:58 pm »
Ok, It's cranking now but the original problem persists. It's back firing thru the tbi with a misting gieser of fuel. Help!
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Offline Dr_Snooz

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Re: 87 p/u won't start
« Reply #5 on: January 16, 2015, 10:02:19 pm »
Sounds like timing to me. If the dizzy is 180 deg. out, it will do that very thing. Out of curiosity, how do you know it's timed if it won't run?
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Offline 78BIG-TEN

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Re: 87 p/u won't start
« Reply #6 on: January 17, 2015, 10:34:01 am »
Its been sitting 5 years and with the old fuel still in it.
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Offline jaredts

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Re: 87 p/u won't start
« Reply #7 on: January 17, 2015, 11:59:22 am »
Good point.  If that is several year old gas your injectors are spraying, it could be more water than anything else.  Is this old gas?
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Offline Tjerica1201

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Re: 87 p/u won't start
« Reply #8 on: January 19, 2015, 05:20:34 pm »
 It's not been sitting for 5 years. Motor was rebuilt 5 yrs ago. I drive it all the time. It sat for a month when these problems started. Water in the gas is a distinct possibility. I will drain and refuel and see if that works.
As far as knowing the timing is correct, I'm putting the timing light on it while im cranking it. Is this not a correct method of checking it for the current situation?  At #1 TDC, rotor points forwardish.  Leans a little tward drivers side, so #1 plug.  So 180 out isn't not the culprit, right?

Thanks for the help guys, keep the advice coming.
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Offline jaredts

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Re: 87 p/u won't start
« Reply #9 on: January 19, 2015, 08:22:51 pm »
If the rotor points toward the#1 plug connection on the cap while #1 is at tdc on the compression stroke then you're not 180 out.  "On the compression stroke" is the key.  If you haven't verified that, you can have an assistant crank the motor while you hold your thumb over the #1 spark plug hole (plug removed).  Once you feel it blow your thumb away you can double check that the rotor is where it should be.
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Offline Dr_Snooz

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Re: 87 p/u won't start
« Reply #10 on: January 19, 2015, 09:54:29 pm »
Quote from: Tjerica1201 on January 19, 2015, 05:20:34 pm
It's not been sitting for 5 years. Motor was rebuilt 5 yrs ago. I drive it all the time. It sat for a month when these problems started. Water in the gas is a distinct possibility. I will drain and refuel and see if that works.
As far as knowing the timing is correct, I'm putting the timing light on it while im cranking it. Is this not a correct method of checking it for the current situation?  At #1 TDC, rotor points forwardish.  Leans a little tward drivers side, so #1 plug.  So 180 out isn't not the culprit, right?

Thanks for the help guys, keep the advice coming.

It's not the way to set timing. You have to set it when the engine is warm and running. Until then, you want the rotor pointing at the #1 spark plug when the crank and camshaft are at TDC. From what you describe, being 180 deg. out is a definite possibility.
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1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline 78BIG-TEN

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Re: 87 p/u won't start
« Reply #11 on: January 20, 2015, 09:23:10 am »
If the engine ran a month ago and all off sudden timing jumped,180 degrees exactly would be extremely unusual.Pull the filter and check for water,then if you find it there go to the tank.Lots of other stuff to check like rotor burn through or tracking\moisture in the cap
« Last Edit: January 20, 2015, 09:25:21 am by 78BIG-TEN »
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Offline Tjerica1201

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Re: 87 p/u won't start
« Reply #12 on: January 21, 2015, 09:58:42 am »
Jared, your method for determining TDC is the same one I used. 

Dr_Snooze, I realize that that is not how to set the timing.  That is just a method I used to determine that I didn't jump a tooth on the timing.  Not that I am entirely sure how far off the tdc mark on the HB would be if it DID jump a tooth.  Any idea?

Big ten, let me know if I follow your line of thinking.  Since it isn't starting but the injectors are flowing, the motor is flooding itself with water/fuel.  Water/fuel is sitting on top of the cylinders, eventually draining past the rings and into the pan.  Water being heaver that oil will collect in the bottom of the pan or in the filter.  So if that is the case, then wouldn't my oil level rise and show as over serviced on the dip stick?  And what is rotor burn through? and Tracking/moisture?

Isopropyl alcohol, I am told, will cause the water to become able to burn (in some magical physics based way).  Is this something any of you guys are familiar with?
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Offline Irish_Alley

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Re: 87 p/u won't start
« Reply #13 on: January 21, 2015, 02:20:08 pm »
how was it running when you parked it?
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Offline Tjerica1201

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Re: 87 p/u won't start
« Reply #14 on: January 21, 2015, 05:51:22 pm »
It was running perfectly last time I parked it.
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