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Acceleration and Hot Start Issues

Damon

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Hello to all, its been a while since I've posted on here. Work and other projects, plus occasional work on the Midget has kept me from posting, but not researching, reading, and applying ideas from these forums.

Anyway, since I've last posted, the Midget's running condition has not really improved...it seems to bog down on acceleration at the 2000-2500 rpm range in second thru 4th gears. When I ease off the accelerator pedal slightly, the car will speed up, and once past the 2500 rpm range it will resume acceleration. It also bogs down on hills.
Then, after running for about 20-30 minutes, if I turn off the key, the car simply will not start. It will crank, and I checked there is fuel delivery at 3psi to the carb, there is spark, but no starting until it sits for another 20-30 min. It does either things whether it is 60 degrees outside or 95 degrees.
I've read through many other posts on this subject, and checked timing, vacuum leaks, tightness of nuts at carb and manifolds, etc. with no luck resolving the problem.
I removed the catalytic converter and replaced with a straight pipe from Moss, so it isn't clogged. The car has a pertronix ignition, new cap and rotor, new coil, new starter, new plugs, new fuel pump delivering correct psi at carb, and I found and replaced an 18" section of wire that had rodent chewed insulation (PO was aware of it as it was poorly wrapped/taped, as well as a loose connection terminal on a wire to the coil.

The car is a '78 Midget 1500 engine with Zenith stromberg carb... I'm at a loss, as is my mechanic brother who I've been getting ideas from via e mails back and forth.
Money is tight and I can't bring it to a mechanic right now. The wife hasn't been able to enjoy the car as I had hoped this summer, and I've held off doing other work such as carpets and new top until we get her going fairly reliably.

Any ideas from you great MG gurus out there?
 
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Has the diaphragm in the carb ever been replaced? Does it have a water choke or a manual choke?
 

texas_bugeye

Jedi Knight
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Vapor lock?
Dont know much about the stromberg carb but could the slid -piston be sticking when it's hot?
crud in the idle air regulator?
Diaphragm stiff cracked?
Does pulling the choke have any affect when it BOGs down?
 

jlaird

Great Pumpkin
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Think I would consider condencer and or points adjusted improperly. Condencers are very cheep and points are free to check.
 
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jlaird said:
Think I would consider condencer and or points adjusted improperly. Condencers are very cheep and points are free to check.



The car has a petronix on it.




Have you checked for vapor locking? Is the fuel line close enough to the manifold to cause this?

Is it the correct coil?

m
 
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D

Damon

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I'll look into some of the other ideas given here. Supposedly the carb was rebuilt just prior to me buying the car for my wife, but who knows for sure?
I don't think vapor lock is an issue, unless the fuel is vaporizing in the carb itself, as I get a strong, full flow directly at the carb itself (disconnect fuel line where it enters carb)even when the car is not starting. Also, because I thought it might be vapor locking, I rerouted the fuel line to come up the firewall and over to the carburator, away from major heat sources. Coil is a Flamethrower ordered from Moss for the car to go with the Pertronix.
As far as choke goes, it has an auto choke (water choke??-don't know what that is???), I was thinking of going to manual choke down the road, but I want to get these other issues cleared up first. I'll probably end up tearing the carburator down and rebuilding it myself just to be sure. I was thinking maybe the float is set too low?
 
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Water choke - choke triggered by coolant temperature.

Just to have some "knowns", I would convert to a manual choke since the water chokes always seem to be troublesome. I would also go ahead and put a new diaphragm in the carb.
 

DrEntropy

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TJ is right, IMO. Losing the hot-water choke to a manual one is good advice. Then you ~know~ the choke circuit is shut down. Also replace the diaphragm, as they can age ungracefully. Pinholes are hard to spot in 'em and time sitting static is a killer.

My take on it would be to just bench it, get a rebuild kit and go right thru it. Then you know what you've got. I'm betting a thorough going-thru and cleaning/rebuild will result in a resolution.
 
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