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nugget
New User
Nov 26, 2008, 7:28 AM
Post #1 of 6
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hard starting gmc sierra
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I have a 1996 GMC Sierra Pick Up, 5.7 V8, 4x4. It is difficult to start in the morning. After the initial start in the morning it will start fine all day. It does not seem to be getting enough gas. It will almost start several times before it actually does start and then runs fine. You can hear the fuel pump work for a couple of seconds when you turn the key on so I guess the fuel pump is OK.
Any suggestions? Thanks a lot!!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 26, 2008, 7:56 AM
Post #2 of 6
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Re: hard starting gmc sierra
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 This item , CTS or "Coolant temp sensor" is highly likely the fault. In fact - more likely the plug than the switch so remove it, spray in some WD-40 in plug end and re-install when cold - see if it works then. If not, spray the threaded area with some PB - power blaster pentetrating solvent so it will remove better and go get one - cheap part but make sure it comes with a new plug end that you can PROPERLY splice in - yellow and black wire.
Propterly: Strip, solder and slide over shrink tubing you'll need to get separately.
Use teflon tape on threads of new or silicone grease.
It just screws into intake manifold right near thermostat and some coolant will leak out but not much. Just catch what leaks in clean pan or replace to full with new 50/50 anti-freeze.
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Tricks by Tom:
1. Plug new one in directly without install and see if that works first! (you only get one chance at real cold)
2. Cut wires to be spliced off by 1/2 inch - IE: yellow longer than black and reverse on vehicle wiring such that spliced area can't ever touch each other if splice failed. Wrap both together without a problem then.
3. 3/4 or 19mm deep socket or better yet a flare nut crowfoot of same is less likely to break the plastic of this spark plug like item.
4. You can "ohm" test unit in place if you wish. ---- Forgot but will read very low or very high with either hot or cold engine or about .177 at room temps....
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Note: Part #TS4015 from NAPA/Echlin (if not superceeded) should come with the pigtail wire. About $20 bucks.
Easy fix as they go. Good luck,
T
(This post was edited by Tom Greenleaf on Nov 26, 2008, 8:07 AM)
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Guest
Anonymous Poster
dddkeeler@aol.com
Nov 27, 2008, 5:25 AM
Post #3 of 6
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Re: hard starting gmc sierra
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Hi Tom, I went ahead and replaced the CTS yesterday but had the same problem when I tried to start it this morning. Any other suggestions?
Thanks for your help and Happy Thanksgiving!!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 27, 2008, 6:13 AM
Post #4 of 6
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Re: hard starting gmc sierra
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If you are satisfied that it and the plug are fine then I'd get a fuel pressure reading and report it back. Couldn't find the spec just now but these would be fussy about being within spec.
Wouldn't hurt to just up and replace fuel filter (on frame rail) get that PB out again as they get stuck from rusty lines up to needing to replace lines if real bad.
Would also try some Techron injector care solvent just because and use that perodically anyway.
This could be a fuel pump issue which is the tougher job and the smaller items should be up to date anyway. Was really hoping you'd be all set with just that CTS but gotta keep checking.
Any stored codes in this? Maybe not but still worth a check on that too.
Try to be as easy as possible on starter if it really takes a while to start. Allow to prime a couple times with key turned to just "run" position and wait there to speed up cold starts till we can get to the bottom of this.
Happy Thanksgiving to you too
T
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Jeff Norfolk
Enthusiast
Nov 27, 2008, 8:56 AM
Post #5 of 6
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Re: hard starting gmc sierra
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Is this a Vortec motor or a TBI? If it is a Vortec motor they are bad about the fuel pressure regulator failing. It is located under the upper intake plem. When they fail they will leak fuel into the intake and cause the engine to "flood" so to speak. This is why when they fail it will be hard to start during your first start of the day. The fuel will be puddled under the intake and you have to crank and crank to get it out. Seems like the engine is not getting enough fuel but infact it has to much.
Jeff
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Guest
Anonymous Poster
Nov 27, 2008, 9:28 AM
Post #6 of 6
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Re: hard starting gmc sierra
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As Jeff mentioned, GM has had some fuel system issuses. The fuel pumps also have bad check valves.
What you can do to verify the prob is in the morning or when you know it won't start is cycle the key 3 to 4 times from off to on w/out cranking... Then try to start, if it starts right up it's in the fuel system.
You can pinpoint it with a fuel gauge & needle nose vise grips. Put the guage on the test port & cycle the key on & check pressure. Pinch off the supply line(rubber hose part) back by the fuel tank. If pressure holds, it's in the pump. If the pressure still drops it's regulator or injector or hose, etc, but any of those require the top plenum to come off so with a quick key on you should see which one it is.....
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