Weak spark when cranking
#1
Junior Member
Thread Starter
Weak spark when cranking
I am stuck on the reason that the spark is weak on my 1980 rx7. Since I am working alone I removed all plugs and clamped them to a steel plate, then connected the wires and used a battery jumper cable to ground the plate direct to the battery terminal. When I crank I se small orange color sparks on the plugs. The plugs are not new but they are in reasonable shape, I have had this car since it was new and seem to either becoming dumb as I age or just missing something basic about the system. Any help is much appreciated. This is the picture of my test rig.
#2
ancient wizard...
Does your car not run,not run well? How old are the consumables? Cap,rotor wires,air filter,fuel filter... plugs i can see and it could use a new set. How about some info on why you're looking at spark quality in 1st place. Freshen up mentioned tune up parts and see if that doesn't help your situation.
#3
Junior Member
Thread Starter
I can not get the engine to start, it has been sitting for a while. The original problem was that the car was misfiring under acceleration. I will follow you suggestions and just replace the basics and see if anything changes. I have pumped out all the gas and started new gas so far, but back to basics is a good plan. thanks for you reply
#4
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you might check coil voltage when its cranking vs not
#5
RX HVN
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Had a similar no-start with my 80 a while back.
Check existing plugs, they 'sparked' so I moved on.
-dropped in new dizzy cap and arm: nada
-check spark wires for connections: nada
-replaced igniters: nada
Finally went back to plugs. What did I have to lose? so I dropped in a new set:
BOOM.
instant start, ran like a Top. Jeez...
Stu A
80GS
AZ
Check existing plugs, they 'sparked' so I moved on.
-dropped in new dizzy cap and arm: nada
-check spark wires for connections: nada
-replaced igniters: nada
Finally went back to plugs. What did I have to lose? so I dropped in a new set:
BOOM.
instant start, ran like a Top. Jeez...
Stu A
80GS
AZ
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GSLSEforme (06-24-20)
#7
Have RX-7, will restore
iTrader: (91)
Exactly!!! Spark plugs play a HUGE role in the way these engines run. I had an SE tbat had a small spot of corrosion on one of the spark plugs. Not on the ground but the head where there are no threads. I cleaned the corrosion as the engine was misfiring like crazy and the corrosion had caused the metal to pit. I pulled some used plugs off the shelf that still looked decent and cleaned them and installed them and the engine ran great. I drive up and ordered two new sets of BR8EQ-14's.
I would recommend duplicating your test with a new set of NGK plugs and seeing if anything changes.
I would recommend duplicating your test with a new set of NGK plugs and seeing if anything changes.
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#8
Junior Member
Thread Starter
Still puzzled
First of all Thanks to all for suggestions. I am trying to get a new set of plugs local, but what are the best replacements for the original NGK BR8ET? Seems like so far I can only find the Champion RC12YC, any other options?
#9
Junior Member
Thread Starter
Weak Spark problem solved
Thanks to all who offered help. In the end its back to basics to solve a problem. A combination of two failures at the same time can cloud the issue. Yes I had bad wires that where new along with failing plugs together. Changed all the parts plugs, wires, cap, rotor and it fired right. I was thinking that my last major carb rebuild and rats nest removal was the source of my problem when I first started to trouble shoot the issue. But checked all my work and the replaced new parts with newer parts and that was it.
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