I need some help guys... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Kybol · 03-30-2004, 11:54 PM

On my engine, the #7 cylinder doesnt seem to be firing. There is spark and compression(about 110) but the header tube doesnt get hot, and it runs the same with or without the plug cap installed. I tried a new plug and a new wire and nothing. I wanna get her running nice for spring, but not to sure where to start.

apstguy · 03-31-2004, 01:15 AM

How about a new cap?

Lynx · 03-31-2004, 02:12 AM

Kybol you have a PM

NeCrOmAnCeR · 04-01-2004, 01:07 AM

Check for vacumme leaks on the intake. Also, many set ups use a vacumme "T" near cylinder #7, so a bad hose there (tranny vacumme modulator, vac ball, etc) will cause a misfire like you describe.

Grim Reaper · 04-01-2004, 11:31 AM

Pull the valve cover and verify the valves are opening. A bust rocker or flat cam lobe could give a OK compression reading but not alow any fuel charge in the cylinder or a spent load to exhast so no boom even thought it has compression.

CRRoy71 · 04-01-2004, 12:27 PM

They make a test light that you put in your plug wire. It will tell you if you are getting fire, then you can go from there.

Grim Reaper · 04-01-2004, 01:43 PM

Quote:

Originally posted by CRRoy71
They make a test light that you put in your plug wire. It will tell you if you are getting fire, then you can go from there.

You don't need a test light! You just need a neighbor hood kid. Stick the plug wire on the kids fingers. Have kid put hand on fender and crank. Kid screams then you got spark.

You can do this with a spark plug. Just play the plug on some metal so it's has a path to ground. Crank and watch for spark at the tip.

CRRoy71 · 04-01-2004, 01:53 PM

I was just trying to be on the safe side. My Dad would always use me as the tester on our lawn mowers. He would say, "here hold this while I pull this cord"

03-30-2004, 11:54 PM	#1
Kybol Registered User Join Date: Mar 2003 Location: Alberta, Canada Posts: 205	I need some help guys... On my engine, the #7 cylinder doesnt seem to be firing. There is spark and compression(about 110) but the header tube doesnt get hot, and it runs the same with or without the plug cap installed. I tried a new plug and a new wire and nothing. I wanna get her running nice for spring, but not to sure where to start. __________________ -90 454ss http://www.imagestation.com/album/?id=4289115843 -04 TRX450R -77 c-10 http://www.imagestation.com/album/?id=4290506213 SOLD -82 c-10 SOLD -02 CRF450 SOLD

03-31-2004, 01:15 AM	#2
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,087	How about a new cap? __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32

03-31-2004, 02:12 AM	#3
Lynx Registered User Join Date: Jun 2003 Location: Fort McMurray, Alberta, Canada Posts: 513	Kybol you have a PM __________________ Ben 1983 Silverado SWB 305 2002 Silverado Extended Cab 5.3 http://members.shaw.ca/bkennett

04-01-2004, 11:31 AM	#5
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	Pull the valve cover and verify the valves are opening. A bust rocker or flat cam lobe could give a OK compression reading but not alow any fuel charge in the cylinder or a spent load to exhast so no boom even thought it has compression. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

04-01-2004, 12:27 PM	#6
CRRoy71 Registered User Join Date: Feb 2003 Location: Mont Belvieu, TX Posts: 852	They make a test light that you put in your plug wire. It will tell you if you are getting fire, then you can go from there. __________________ Chris '92 ext. cab s/b 4.3L "Sparky" '04 crew cab 2500 4x4 6.0L

04-01-2004, 01:07 AM	#4
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	Check for vacumme leaks on the intake. Also, many set ups use a vacumme "T" near cylinder #7, so a bad hose there (tranny vacumme modulator, vac ball, etc) will cause a misfire like you describe.

04-01-2004, 01:53 PM	#8
CRRoy71 Registered User Join Date: Feb 2003 Location: Mont Belvieu, TX Posts: 852	I was just trying to be on the safe side. My Dad would always use me as the tester on our lawn mowers. He would say, "here hold this while I pull this cord" __________________ Chris '92 ext. cab s/b 4.3L "Sparky" '04 crew cab 2500 4x4 6.0L



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