| [GMCnet] Amazing Results [message #74632] |
Sun, 21 February 2010 22:04  |
James Moore
Messages: 71
Registered: January 2004
Karma: 0
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While this involved my 1978 Blazer, it probably applies to GMC Motorhomes.
I recently put my Blazer back on the road after sitting for a year or so.
It didn't run well with misfiring under load and jerking and jumping when I
engaged the clutch while at a stop and was down on power. I rebuilt the
carb with no change. I inspected the distributor cap, vacuum and
centrifugal advances and rotor and found nothing wrong. Then the engine
started to die going down the road. It would cut out for several seconds
and restart. Then it started to die and not restart but would restart
immediately when I turned the key to the start position. I replaced the
ignition module and didn't cure the problem.
On night I noticed that when the engine died, the lights on alarm buzzer
activated even thought the ignition swich was on. When I moved the
ignition key slightly the buzzer stopped. The next time the engine died, I
moved the ignition key and the engine immediately restarted..
Yesterday I replaced the ignition switch. The engine doesn't die, it idles
smoothly, it doesn't jerk and jump when I engage the clutch, the power is
back, the engine runs better when cold, and it doesn't misfire under load.
I guess the ignition switch had high resistance and was dropping the
voltage to the HEI causing it to malfunction.
Reading about all the strange things GMC's do makes me wonder if the
ignition switch has dirty contacts and is causing the problems. The one I
installed cost less than $20 and took less than 1 hr to install.
Jim Moore
75 PB that has been sitting since 2007
Battle Ground W
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| Re: [GMCnet] Amazing Results [message #74633 is a reply to message #74632] |
Sun, 21 February 2010 22:11  |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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They say having too many keys on the keychain can cause this and also the tumblers in the lock to wear out...
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] Amazing Results [message #74701 is a reply to message #74632] |
Mon, 22 February 2010 13:25 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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depends on the make, I guess.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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