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Discussion Starter #1
Has anyone ever heard of a problem related to warm starts and the bump switch in a Mark II Roadster (no I'm not making this up!!)Long story short. The car starts cold...no problem. The problem arises once the car is warm. Try to start the car warm...no go...just cranks over...won't light. Get out, open trunk, pull shorting plug out of spot where bump switch was, turn car over (won't start w/ jumper plug pulled out), put jumper plug back in, car starts normally. (Pulling the plug out, cranking the car over and re-installing the plug seems to act as a "reset" of some kind). The car will start without routine mentioned above if you push accelerator to the floor while turning it over. It is a zany problem. The car supposedly has all 93 mustang running gear. If anyone has ever heard of such a problem with warm starts please let me know. The "pro" that built the car for me won't return email/phone calls and he lives too far away for me to personally strangle him so I am turning to you guys. I would greatly appreciate any comments. Thanks in advance.
 

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FFCobra Captain
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What's a bump switch, and is it EFI?

If by pulling the bump switch jumper out (whatever that is) somehow kills power to the computer (if you have one), then when you plug it back in, the computer will reset itself..so that could be a direction to look in.

Some people have had problems with a TFI module in the distributor when they get hot. I'm not sure how you test that, maybe that's worth looking at. I think the TFI isn't that much money, so if others agree, maybe try changing that out and see if the problem goes away. That's a lot cheaper than dropping in a new computer.

Of course, if you have carb, all of my suggestions are moot.
 

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I sounds like you have a flooding problem which could be related to an injector or injectors which are leaking down. The reason that unplugging the inertia switch fixes the problem is that it stops the pump and allows you to clear the cylinders.

Cheers, Rod
 

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Yes, dv/dt has it. Here is a bit more analysis.... I assume the bump switch you mention is the fuel pump cutoff switch. By triggering this then turning the engine over you are clearing out the excess fuel that has flooded the engine. Reseting the pump again gives the engine a chance of firing up normally afterwards.

The method of putting your foot to the floor also has the effect of allowing lots of air to flow through the engine but less fuel, also leaning out the mixture.
 

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FFCobra Craftsman
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pull shorting plug out of spot where bump switch was,
Does that mean you do not have the inertia switch installed? You just have a jumper of some kind plugged into the connector the inertia switch is suppose to attach to? If so, I'd go to the trouble of traveling to the residence of the "pro" so you can throttle him. Eliminating the inertia switch serves no purpose and may prove dangerous if the vehicle is in an accident.
Your flooding problem could be related to the injectors installed in the engine. If the "pro" installed larger than stock injectors in the engine, but installed the stock mass air sensor, it will run richer than it should, and it will flood easier too. What color are your injectors? I believe the stock ones (19 lbs/hr) are tan.
 

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Discussion Starter #6
Originally posted by Dan Babb:
What's a bump switch, and is it EFI?

If by pulling the bump switch jumper out (whatever that is) somehow kills power to the computer (if you have one), then when you plug it back in, the computer will reset itself..so that could be a direction to look in.

Some people have had problems with a TFI module in the distributor when they get hot. I'm not sure how you test that, maybe that's worth looking at. I think the TFI isn't that much money, so if others agree, maybe try changing that out and see if the problem goes away. That's a lot cheaper than dropping in a new computer.

Of course, if you have carb, all of my suggestions are moot.
 

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Discussion Starter #7
Dan,

Thanks so much for your response. You guys on this board are great. The car is EFI so your response is greatly appreciated. Gives me a place to start. Thanks again.

dave
 

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Discussion Starter #8
Originally posted by dv/dt:
I sounds like you have a flooding problem which could be related to an injector or injectors which are leaking down. The reason that unplugging the inertia switch fixes the problem is that it stops the pump and allows you to clear the cylinders.

Cheers, Rod
 

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Discussion Starter #10
Originally posted by PAB:
</font><blockquote>quote:</font><hr /> pull shorting plug out of spot where bump switch was,
Does that mean you do not have the inertia switch installed? You just have a jumper of some kind plugged into the connector the inertia switch is suppose to attach to? If so, I'd go to the trouble of traveling to the residence of the "pro" so you can throttle him. Eliminating the inertia switch serves no purpose and may prove dangerous if the vehicle is in an accident.
Your flooding problem could be related to the injectors installed in the engine. If the "pro" installed larger than stock injectors in the engine, but installed the stock mass air sensor, it will run richer than it should, and it will flood easier too. What color are your injectors? I believe the stock ones (19 lbs/hr) are tan.
</font>[/QUOTE]
 

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Discussion Starter #11
Yes, I yanked the fuel cutoff swith and shorted it for trouble shooting purposes (dangerous, I know. I'll check to see what color they are. I am pretty sure he has the stock injectors in there but I'll check it out. Thanks for your help.

Dave
 
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