Disabling fuel system for compression test? - TerrainForum.net: GMC Terrain Forum
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post #1 of 42 (permalink) Old 01-03-2017, 07:34 AM Thread Starter
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Disabling fuel system for compression test?

Hi all,
Has anyone here done a compression test on an 2.4l. I have a 2011. I plan to do a compression test... Mostly to satisfy my OCD and to make sure there is nothing wrong while I have a warranty.
I believe i can just pull the off and even coil fuses for the ignition. I don't know how to shut off the fuel system. I thought about pulling the wire from the high pressure fuel pump. I can't find any fuse for this.

Any suggestions?

Got the compression gauge from AutoZone as a free rental 😊

Jeff from Iowa, Purchased 2011 Nox in Nov. 2016, Manufacture date 10-10, 2.4l, AWD
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post #2 of 42 (permalink) Old 01-03-2017, 11:13 AM
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Re: Disabling fuel system for compression test?

Have you tried all of the fuses ? There are some BCM fuses by the passenger side of the console. Also, it may be a relay and not a fuse.


2010 Equinox LTZ<br />4 cyl, FWD, S/R<br />Cardinal Red/Black
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post #3 of 42 (permalink) Old 01-03-2017, 11:14 AM
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Re: Disabling fuel system for compression test?

There are two fuel pumps the one under the hood has no wiring to disconnect as it is purely mechanical and supplies high pressure to the injectors.

The low pressure pump is in the tank and is controlled by a module in the interior driver side wheel well area. The fuel system of the Equinox has no return line. Fuel pressure is sensed and that signal is sent via computer to the control module. The module speeds up or slows down the pump motor. So there is no relay or fuse to disconnect.

http://www.wholesalegmpartsonline.co...wd=&origin=pla

Here is a link that may help with you compression check. It's not exact for your vehicle, but may be of use.

http://workshop-manuals.com/chevrole...ons/page_2059/

Have fun!
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post #4 of 42 (permalink) Old 01-03-2017, 03:31 PM Thread Starter
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Re: Disabling fuel system for compression test?

Thanks Rit and Spook,

Spook, just to be clear, the fuel control module in the rear driver's side will shut down the fuel system?
Also the other link mentions that the power train control module must be removed... Where is that?

I started to do this assuming it was going to be easy to find the fuses etc.... Arghhhh

Already changed my spark plugs and cleaned the throttle body which was so easy. Just changed my transfer case and differential fluid which was simple.... and very necessary, very black.


Jeff from Iowa, Purchased 2011 Nox in Nov. 2016, Manufacture date 10-10, 2.4l, AWD
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post #5 of 42 (permalink) Old 01-03-2017, 04:34 PM
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Re: Disabling fuel system for compression test?

New to the nox,

Unplugging that module will disable the fuel pump.

Full disclosure:

I have not personally ever done this nor ever had a need to do any of this, and in all honesty I never really thoroughly read the linked to procedure on compression testing the engine. So I can't say the procedure is good or bad.

While I enjoy working on all types of machinery, I am not an auto mechanic (and never professed to be one). What I really get off on is digging through the web for knowledge and digesting technical writings. As close as I ever got to being a car mechanic was staying at a Holiday Inn one time.

Have a great day and be safe.
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post #6 of 42 (permalink) Old 01-05-2017, 05:35 PM Thread Starter
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Re: Disabling fuel system for compression test?

Thanks!

I will let you and future readers how it goes when I am finally able to do this.

Jeff from Iowa, Purchased 2011 Nox in Nov. 2016, Manufacture date 10-10, 2.4l, AWD
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post #7 of 42 (permalink) Old 01-06-2017, 11:27 AM
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Re: Disabling fuel system for compression test?

The one I have in my box looks just like this.
Very easy to use and no need to use the key to crank.
By connecting the switch directly to the starter, the ignition stays in the off position.


http://www.sears.com/lisle-switch-re...Q&gclsrc=aw.ds

2014 Equinox LTZ FWD 3.6L. V-6 (LFX)
GM6T70 Transmission-Gen II(M7W)
Crystal Red Tintcoat-Brownstone Leather-(FE2) Suspension-18" Wheels
Build Date: Nov. 04, 2013-Delivery Date: Nov. 25, 2013
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post #8 of 42 (permalink) Old 01-06-2017, 12:50 PM
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Re: Disabling fuel system for compression test?

Quote:
Originally Posted by rednox301
The one I have in my box looks just like this.
Very easy to use and no need to use the key to crank.
By connecting the switch directly to the starter, the ignition stays in the off position.


http://www.sears.com/lisle-switch-re...Q&gclsrc=aw.ds
What's wrong wtih just turning the key and holding for 5 seconds? Also, you can just hold the gas pedal all the way down while you crank the engine for the 5 seconds.

Additionally, if you think your rings might be bad, you may want to consider doing the "wet" compression test with a few squirts of oil in the cylinder (after you finish with your dry tests). When I did this on my V6 '97 Taurus, the readings shot up (Cylinder/PSI Increase): 1/35, 2/25, 3/19, 4/26, 5/27.5, 6/25 ... so the rings were shot (in addition to the head gasket).

But this was at 226,000 miles.

2011 Equinox 1LT (new Jan 2011): Summit White / 3.0 L V6 / FWD / Pioneer Stereo / 18" Wheels / 108+k miles (June 2017)

2002 Impala 1LT (new Jun 2002): Summit White / 3.4 L V6 / FWD / Cassette-CD Combo /202+k miles (June 2017)
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post #9 of 42 (permalink) Old 01-07-2017, 05:43 PM Thread Starter
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Re: Disabling fuel system for compression test?

So I did the compression test. I warmed up the car first. Unclipped the rear driver's side area fuel module. It is grey and needs a screwdriver to unclip it. Pain to get it removed with the plastic sidewall.

Removed the odd and even coil fuses.

Took about 15 turn overs to get it up to top compression.
Compression:
235
240
245
250

Jeff from Iowa, Purchased 2011 Nox in Nov. 2016, Manufacture date 10-10, 2.4l, AWD
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post #10 of 42 (permalink) Old 01-07-2017, 06:07 PM
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Re: Disabling fuel system for compression test?

Quote:
Originally Posted by New to the Nox
So I did the compression test. I warmed up the car first. Unclipped the rear driver's side area fuel module. It is grey and needs a screwdriver to unclip it. Pain to get it removed with the plastic sidewall.

Removed the odd and even coil fuses.

Took about 15 turn overs to get it up to top compression.
Compression:
235
240
245
250
Wow - I have never seen compression reading so high. Guess these engine really are high compression.

Very good consistency.


2010 Equinox LTZ<br />4 cyl, FWD, S/R<br />Cardinal Red/Black
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