68, 289, automatic, wont start hot - Ford Mustang Forum
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post #1 of 13 (permalink) Old 05-04-2016 Thread Starter
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68, 289, automatic, wont start hot

Same problem for years now...many mechanics have looked at...suggestions range from insulate the heater, gas line. etc with no difference. If i drive it and it sits for more than 10 mins, it wont start. BAsically eveything under the hood is new or rebuilt. Starter was installed 3 years ago, and has always started great cold and crappy or not at all when hot. insulating made zero dif. could it be the starter? i always buy a basic one from a reg auto parts store and have never had a problem...pain in my rear.thanks

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post #2 of 13 (permalink) Old 05-04-2016
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Your going to have to explain in better detail what you mean by "won't start".......


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post #3 of 13 (permalink) Old 05-04-2016
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Is it cranking but not catching? That honestly sounds like heat soak in the carb, have you tried a carb spacer? I had this issue w/my car 2 summers back. Carb spacer fixed it.
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post #4 of 13 (permalink) Old 05-04-2016
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Photos of you engine bay would help. If you have done all the things you allude to, did you put in 3 new good battery cables? Put in a new engine wire harness?

Whatever tests you do they need to be done while everything is hot, just like at shutdown. It could be something expanding in the starter circuit and binding or opening a circuit.

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post #5 of 13 (permalink) Old 05-05-2016
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randyray01,
Most electrical problems can be traced to poor grounding of the electrical component. I would make sure the ground cable from the battery to the engine block is tight on the block AND going to bare metal , not a painted surface. I would look there and possibly add another ground cable to a major frame component and a bellhousing bolt neart he starter. You might be surprised at the outcome.
Randy
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Last edited by Gt350HR; 05-06-2016 at 01:37 PM.
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post #6 of 13 (permalink) Old 05-05-2016
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Quote:
Originally Posted by Gt350HR View Post
randyray01,
Most electrical problems can be traced to poor grounding of the electrical component. I would make sure the ground cable from the battery to the engine block is tight on the block AND going to bare metal , not a painted surface. I would look there and possibly add another ground cable to a major frame component and a bellhousing bolt near he starter. You might be surprised at the outcome.
Randy


Bingo!!!!!! plus it might just be heat soak or ignition timing....just because the book says "X", that may not be what the engine likes and most of the "modern mechanics' don't understand this (including dwell)

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post #7 of 13 (permalink) Old 05-06-2016
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Sounds like some more information is needed. After it sits, will it not turn over? If that is the case, it could be heat-soak in the starter. My 1983 GT did this...would cold start just fine but then would barely (or not at all) turn over when hot. I was able to determine it was my starter by running it until hot, shutting it off, and then I slowly drizzled water from a garden hose on the starter to keep it from soaking up the heat after shut-off. When doing that, it did indeed start right back up...but when shutting it off and letting it alone, would not start each time. I replaced the starter and it was fixed. I eventually replaced it with a smaller high-torque starter that I was able to wrap insulation around and have had no problems at all. However, if your car is turning over but just not starting, the ignition module could be faulty...had this happen on a Jeep (it would start and run fine and then would not restart once shut off until the module cooled down). If you are still getting spark, then my guess may be vapor locking. Hopefully this helps.

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post #8 of 13 (permalink) Old 05-06-2016
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Third for what gt350 said!

Had the same issue for years, and mine turned out to be the cable to the starter was worn and cracked. A couple of dollars later, I've never had that issue again. For a laugh, I found the crack in the cable when I was replacing my tie rods due to a cracked boot that was found when I was chasing an oil leak. Still got the oil leak!
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post #9 of 13 (permalink) Old 05-06-2016
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Bad ground or corrosion in cable-use 200 grit sandpaper and clean all cable connections! Wes
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Bad ground or corrosion in cable-use 200 grit sandpaper and clean all cable connections! Wes
Agreed this could be the culprit. If the cables and connections look good, you could test the cables for resistance in case they have internal issues (that you can't see). If the cables are old, would probably be worth just picking up some new ones since they are relatively cheap. As others have said...make sure the connections are clean...just a little bit of corrosion can cause a big drop.

-1983 5.0 GT Red/Black.5MT.3:73.FMS Lowering Springs
-2011 5.0 GT Prem.Kona Blue.6MT.19" Nickel Wheels.3:73.Comf Pack. Blk/Cshmr Int
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post #11 of 13 (permalink) Old 05-11-2016 Thread Starter
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Thanks all! Im hoping its the starter because all the grounds and cables are fine. Dont know what a carb spacer is...
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Quote:
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Thanks all! Im hoping its the starter because all the grounds and cables are fine. Dont know what a carb spacer is...
Apparently, neither do your "mechanics". Especially if they are not familiar with our old cars with carbs. A carb spacer fit's between your carb and the intake manifold. Ideally, you chose one made out of a material that limit's the transfer of heat. Heat from the engine is transmitted to the intake and onto the carb. Two conditions occur when an engine is shut down after a prolonged drive...
1.There is a condition called "heat soak". This is where the engine temps increase to a certain point beyond those temps when the engine was running before you stopped. Perhaps, 15-25 plus degrees. This increase can cause fuel to "boil" or vaporize in the lines and in the carb fuel bowl. This sets up the second condition ......
2. "Vapor lock" this is the result of that "super heat" finding's way to the carb bowl and fuel entry lines. The fuel will vaporize, therefore, when fuel is called for, liquid is not dispensed or available , instead you have "vapors".

Starters are prone to be affected by this "super heat" as the windings may expand if the heat is too extreme, and the armature will rub the field windings and other nasty stuff.

So, how do you minimize this stuff?
1. Insure your cooling system is "spot-on" (numerous little tips available)
2. Add a phenolic carb separator, perhaps, a 1/4 to 1/2". Be mindful of your hood clearance.
3., Timing to far advance can add to the previous 2.

Perhaps, others will offer other tips......Good Luck

Ken
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Randy,

I don't see that you answered the question about your starter. Does it turn the engine? If so, your problem is not the starter.

This is the worst month of the year for hot restart problems. 'Summer' gas is not quite available yet so warm days combined with 'winter' gas can cause this kind of a problem since the fuel will evaporate from your carb while sitting on top of a hot engine. Even if the carb still has some gas in it, what gas did evaporate sinks into the intake manifold and causes a very rich mixture. Either way it causes a hard re-starting problem. With your 90F temps this week it could be a problem for any car with a carb.

While a carb spacer can help some those mostly help while the car is running. I have a temperature probe inside my air cleaner and summer temps of the air going into the carb can reach 160F. That has nothing to do with a spacer (this car HAS a spacer); its just the temp of air coming through a 200F radiator on its way to the air cleaner. As long as the engine runs, vaporization of the fuel flowing through the carb cools the carb enough that you don't see much of a problem. Once you shut down the engine there is no fuel flow and the carb is sitting in a bath of 160F air. Even if you have a carb spacer the whole affair is going to get hotter. Since even summer gas starts to boil at 100F its not much of a stretch to assume that 160F is going to boil the fuel in your carb. Winter gas boils at an even lower temp making the problem worse.

With a spacer the carb is somewhat isolated from the engine and will operate a few degrees cooler. The standard V8 Ford intake manifolds have an exhaust passage that intentionally heats the area directly under the carb. What makes an even bigger difference than a carb spacer is to block that passage so exhaust heat is not going directly into the carb. I have done both but even that does not completely eliminate the problem since you still have that 160F air to contend with.

There is no magic solution other than realizing what is happening and not doing anything to make it worse (such as pumping the gas pedal). To some extent, it happens to all cars but ones with carbs see a bigger problem. Depending upon how empty your carb bowl is, you may have to crank the engine for a few seconds to refill the bowl before you can expect the engine to start. Holding the gas pedal wide open during that time, as you would do for a flooded engine, might also help.
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