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Help with intermitent ignition

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Largo_Larry

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I'm the very proud owner of a 74 TR6 that is in excellent shape and has run great for the five years that I have owned it. It is basically stock except for an electronic fuel pump and Allison XR700 electronic ignition system.

The car is a weekly Sunday driver. Last weekend while on my drive (approximately 20 miles round trip) I experienced a unique problem. The first sign of a problem was a brief loss of power (1/2 a second) while cruising at 40 MPH about 5 miles into the trip. The next sign came on the trip home about 10 miles later when the engine cut off until the engine speed dropped to near idle levels then the engien came back to life and ran smoothly. Over the next 1/2 mile these same symptoms repeated themselves (exactly) several more times. Then as soon as the problem started, it stopped without a hint of trouble the last five miles back to the house.

While I guess it could be a fule issue, the feel and characteristics of the problem lend me to believe it is an electrical problem.

The first thing I did when arriving home was to check for loose connections under the hood. Finding none, I pulled the distributor cap and everything looked in good shape and secure. I then started the engine and wiggled the various electrical connections under the hood and around the starter switch. Unfortunately, the engine just sat there and purred at me.

At this point I suspect that the Allison unit is at fault but I'm not sure. Has anyone experienced a problem like this? If I do decide to change out the ignition system does anyone have a recommendation? I'm mostly interested in keeping the engine running smooth and reliable rather than worring about maximizing power.

Thanks for any help/advice that you have.

Larry
 
My TR3 has a bad connection (bad connection!, bad!) somewhere around the back of the ignition switch. It happens so seldom and so irregularly that I have never tracked it down but have become adept at reaching up there and wiggling the wire before the RPMs drop more than 200 or 300.

A total ignition failure does feel quite different from a fuel problem -- loss of ignition is immediate and total... no degrees of sputtering, coughing, etc. so your instincts are probably right.

Lots of different opinions on ignition alternatives, but for smooth and reliable I prefer the original points system.
 
I have had fuel problems that have been of this nature. These turned out to be due to a fuel filter AHEAD of the pump(never do this!!) On another car it was a leaf in the tank from a vandel(who I will someday track down and strangle). The symptoms were very similar in each case.
I would suggest you clean out the tank, and put on fresh fuel lines up to the pump. Old flex lines swell shut over time, steel rusts and catches debris......
MD(mad dog)
 
OK, he goes a really funny story, hod your same problem and had to go get my friend on four afternoon outings, even changed a fuel pump in the middle of no where. Stopped again 2 miles from the house and in just checking the wires, the + lead on the coil from the XR700 came out in my hand, not even crimped from the factory, a little solder and no more problems, and we pay good money.
 
Larry,
I hate to tell you this, but it could very well be that the module on you electronic ignition is going out. I went through three electronic ignition system, two Crane (Allison) 700 and a 3000. All bad. When they go, they go.
I went back to points and condensor (stock) and have solved the problem. Thought about trying the Petronix but got talked out of it, on this forum. Go back to stock, you won't regret it. Now that said, some on this forum will report no problems with electronics, but I think that most concur that stock is the way to fly.

Bill
 
Thanks everyone for your advice. This morning I changed out the electronic ignition for points and condenser and took a nice long drive. The car ran great with no hick-ups. Hopefully that was the problem, only time will tell. I think I will stay with the "old school" points system.

Thanks again!

LArry
 
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