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Discussion Topic:
New Miss
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RAND |
02-17-2016 @ 6:14 PM
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Member
Posts: 56
Joined: Sep 2012
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Hi there... I've developed a miss in my 50 Merc that I just cant seem to pin down It idles fine Runs fine cold But once 1/2 way warmed up it miss's Never has flat out died This is what I've done so far... 1) Changed condenser 2) Changed coil 3) Changed spark plugs 4) New points 5) Ran engine in dark looking for plug wires sparking 6) Fresh rebuilt Carb by Daytona I cant figure out why it miss's when its warm and not when its idling or cold?? Seems electrical idk?? Im also wondering if it could be the wire in the dizzy grounding out? Kinda acts like when my loose OD wire grounded out. checked that its ok Could it be fuel filters? seems electrical tho? I have a filter back by the tank and the electric pump and I have a Napa filter in the glass bowl could it be the cork gasket at the glass bowl Seems if it was fuel related it would do it all the time..No? Thanks for your suggestions, Rand
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cliftford |
02-17-2016 @ 10:06 PM
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Senior
Posts: 845
Joined: Jan 2014
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Is this a steady miss like a cylinder not firing? If so when it's missing pull the plug wires one at a time with the engine running and see if you can narrow it down to one cylinder. It might be a valve sticking. If it's a more intermitant miss it could be fuel or ignition related.Could the dist. shaft bearings be badly worn? These things are tough to diagnose on line.Good luck.
This message was edited by cliftford on 2-18-16 @ 4:08 AM
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Tracker |
02-18-2016 @ 9:07 AM
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New Member
Posts: 163
Joined: Oct 2009
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Randy...what you describe is perfect definition of what happened to my 51 Merc earlier this year with a slight miss and gradually getting worse til it would not run at all. Suggest you pull your distributor so you can inspect the primary wire buried under the plate..it was originally covered in cloth that rots away with time & shorts out against the distributor shaft. Its an easy fix if you discover its got bare wire showing & you can make it up yourself as a single wire from dist to coil. If that wire has never been changed, bet you will find as I did that its shorting out every time you hit the accelerator when the plate advances. Tom O gave me the guidance to fix my car and I hope his advice that I'm passing on to you works as well for you as it did for me . Good luck. Let us hear how you make out. Tracker PS Sent you a glass taillight a few years back ...how did that work for you ?
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RAND |
02-20-2016 @ 10:34 AM
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Member
Posts: 56
Joined: Sep 2012
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Update... Today with no improvement I.. 1) Replaced the Dizzy Cap and Rotor button, Visually looked at wire in the dizzy and gave it a wiggle. I replaced that wire some time ago. 2) I also did a vacuum test and got 18 to 20 inch reading 3) Hard to determine miss at idle, seems to run fine at idle, miss's while driving in neighborhood, worse turning around in cul de sac. Never has flat out died. 4) Merc has auto choke so I cant pull the choke to give it more fuel. I did hit the mechanical fuel pump switch with no improvement. Also wiggled ignition switch To do: Pull Dizzy to inspect wire Check coil and condenser with a volt meter (how do I do that?) Change 2 fuel filters Squirts some starting fluid in carb for more fuel (hard to do while driving tho) Check plug wires with timing light, how else can I check those? Replace ignition switch? Could it be carb related? Fresh rebuilt from Daytona Any other ideas? Never has completely died or not started It feels like electrical shorting out?? but where and not at Idle?? Thanks for any ideas, Randy Rand is online now Report Post
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carcrazy |
02-20-2016 @ 10:54 AM
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Senior
Posts: 1680
Joined: Oct 2009
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There could be some small particles in your fuel system or carburetor that are temporally blocking a fuel passage. If you have solid metal core ignition wires the following won't be a problem, plug wires resistance increases with temperature. I have had carbon core ignition wires that, once they aged (about 70K miles) would go from relatively low resistance to infinite resistance when heated up. The car would idle and run fine until it heated up - about 10 or 15 minutes of running time.
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TomO |
02-20-2016 @ 11:08 AM
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Senior
Posts: 7263
Joined: Oct 2009
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Check your spark when the engine is warm and at speeds above idle. Reasons for a weak spark are coil and condenser, also the rotor and cap. You could also have an intermittent spark due to bad wire in the primary circuit, bad ignition switch or bad primary wire. A bad coil or condenser could also cause this. If your spark is OK, check the spark plugs for a lean or rich condition.
Tom
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TomO |
02-20-2016 @ 11:09 AM
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Senior
Posts: 7263
Joined: Oct 2009
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Check your spark when the engine is warm and at speeds above idle. Reasons for a weak spark are coil and condenser, also the rotor and cap. You could also have an intermittent spark due to bad wire in the primary circuit, bad ignition switch or bad primary wire. A bad coil or condenser could also cause this. If your spark is OK, check the spark plugs for a lean or rich condition.
Tom
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RAND |
02-20-2016 @ 1:24 PM
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Member
Posts: 56
Joined: Sep 2012
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Hi Tracker I didn't use the Ford reverse lights that you sent me. I was looking for the Merc lenz. I tried to pass them along to someone else but still have them om my shelf. I did finally find a Merc lenz and hooked them up to my break lights for added lighting while breaking. 6volts just arent very bright for today's drivers. Do you want them back? Thanks, Randy PS I tried to attach pictures with no luck
This message was edited by RAND on 2-20-16 @ 1:27 PM
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Tracker |
02-20-2016 @ 10:17 PM
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New Member
Posts: 163
Joined: Oct 2009
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Randy....when you say your car does fine until it heats up & then starts to miss was the xact same symptoms I had. My money is still on the primary wire ...either shorting or bad. Can't see it shorting at night. Sorry about the wrong light going out ...keep it or pass it on to someone who can use it. Hope you get to the cause of the problem .
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TomO |
02-21-2016 @ 6:19 AM
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Senior
Posts: 7263
Joined: Oct 2009
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Randy, Did the symptoms appear or get worse after the carb was rebuilt? Does it get worse turning and when you accelerate hard? Does the engine respond normally when you accelerate when standing still? Your float level could be set wrong if the answer to these questions is yes. Run the car at idle and check the fuel level in the carb by removing the top. If it is near the correct level, lower it about 1/16". If it is low, raise it about 1/16". If the answer is no, check the wire to the ignition switch for any bare spots or a loose connection. check for loose connections inside the distributor or a poor ground on the condenser.
Tom
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