Author Topic: Engine missing at all RPM levels  (Read 4126 times)

sixt9x33rs

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Engine missing at all RPM levels
« on: December 10, 2010, 02:27:34 AM »
I want to share an experience that I recently had with my 69 Z.

My motor slowly started missing while the fuel level was very low. I thought that I had trash in the carb, so I took the carb off and disassembled it cleaning it thoroughly. Put it back on same result. However, the miss was getting worse. Then thought I had bad gas because of the way the car was running so I went and bought Marine Sta-bil...thinking I had water in the fuel. Still no positive results. Finally replaced the points, and this helped but only for a short time. I then replaced the condensor and that solved the problem. While I was at it I replaced the rotor button and the distributor cap. The old adage came true with my issue...90% of carb problems are electrical!!
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

BlackoutSteve

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Re: Engine missing at all RPM levels
« Reply #1 on: December 10, 2010, 02:55:22 PM »
Good post. ;)
The poor old carb gets the blame for just about everything.  :-\
Restoring my RHD 69 Jane in Melbourne, Australia.
http://www.usmuscle.com.au/Forum/showthread.php?t=2840

sdkar

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Re: Engine missing at all RPM levels
« Reply #2 on: December 21, 2010, 10:51:28 AM »
How do you know what RPM level the engine is at if it is missing? 

Stingr69

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Re: Engine missing at all RPM levels
« Reply #3 on: January 03, 2011, 06:19:03 PM »
I don't think sta-bil will remove water as it is primarily intended to keep gas from going bad over time, not treat it for water...but i could be wrong.

"Heet" brand gas dryer is what I would try.

-Mark.

BlackoutSteve

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Re: Engine missing at all RPM levels
« Reply #4 on: January 05, 2011, 09:37:27 PM »
I don't think sta-bil will remove water as it is primarily intended to keep gas from going bad over time, not treat it for water...but i could be wrong.

"Heet" brand gas dryer is what I would try.

-Mark.

A small dose of methylated spritis does the trick. It's hydroscopic and absorbs water. 12oz to a full tank of gas would be fine.

I only know Sta-Bil to be a fuel preserver.
Restoring my RHD 69 Jane in Melbourne, Australia.
http://www.usmuscle.com.au/Forum/showthread.php?t=2840

RobF

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Re: Engine missing at all RPM levels
« Reply #5 on: October 21, 2011, 03:35:45 PM »
I just went through the same problem on my 67 SS350. It started out as a random misfiring at idle and a backfiring problem under WOT. Eventually, deteriorated to not being able to start it at all.  Given the backfiring problem under load, I was thinking ignition. I checked a few plugs, was getting spark, so I decided to go through the carb too. No change.  I was thinkiing that the points/condensor - although old (12 years +, 1000 miles) should be ok, right? Never heard of a condensor going bad.

After letting the car sit for most of this summer (just didn't feel like working on it - too busy), I finally bought a set of points/condensor/rotor, took 5 minutes to install them, and the engine fired right up. Runs great now, all issues resolved.  Oh well, carb freshening didn't hurt as the car does not get much use. I feel a bit silly for letting the car sit idle all summer for such a simple problem.  Now - trying to get as many drives in as possible before the Michigan winter arrives!


Kelley W King

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Re: Engine missing at all RPM levels
« Reply #6 on: October 21, 2011, 07:57:53 PM »
Don,t forget vacuum leaks. I did carb adjusting, plugs ,ect. Took off the carb for work and what do you see? Cracked booster line. Fun day though but I messed with so much stuff it took another day to tune it back like it was. If it wasn,t for the Hookers and Flowmasters I probably would have heard it first.
69 Z28 RS Scuncio Hi Performance
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77 Trans Am Special Edition

LM69Z28

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Re: Engine missing at all RPM levels
« Reply #7 on: October 22, 2011, 04:45:33 AM »
To Blackout Steve
Does the Methylated spirits work for just normal watery gas like we have her in California and can it be used all the time or? I blow so much moisture out of the tail  pipes at times I can't believe the car actually runs but I mix the 91 unleaded with leaded 111 race gas so that really helps!
Will the Methylated spirits conflict with the leaded gas and cause any problems you know of?
Thanks for the help
Michael Kellogg
LMN68Z28 ;)

Stingr69

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Re: Engine missing at all RPM levels
« Reply #8 on: October 22, 2011, 02:07:15 PM »
To Blackout Steve
Does the Methylated spirits work for just normal watery gas like we have her in California and can it be used all the time or? I blow so much moisture out of the tail  pipes at times I can't believe the car actually runs but I mix the 91 unleaded with leaded 111 race gas so that really helps!
Will the Methylated spirits conflict with the leaded gas and cause any problems you know of?
Thanks for the help
Michael Kellogg
LMN68Z28 ;)

The moisture out the tailpipe is just a byproduct of combustion. You will get CO2 and H2O (and lots of other things too) from combustion. It condenses inside the tailpipe and you blow it out at start up. You will not see much of it once the exhaust system heats up fully because water exits as a gas above 212 or so.

-Mark.

-Mark.

-Mark.

LM69Z28

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Re: Engine missing at all RPM levels
« Reply #9 on: October 22, 2011, 02:23:03 PM »
Mark
Right, got it thanks so much!
LM69Z28