The subject- A rescued 1981 Mazda rx7, condition: fair/poor.

*issue: vehicle has an attitude about starting on its own.
*The car’s timing has been set and reset.
* has new: spark plugs& wires, distributor cap& rotor, and ignition coils.
* carb is rebuilt, full of fuel and gives a generous squirt.
ALTHOUGH!!!!!! if the vehicle is bump/ pull started, it will run perfectly smooth and drive-able. Until you turn it off or kill it.
Please help if you can Gretchen has been off the road too long and is missing it’s daily abuse.
Thank you greatly

 

Do a compression test. Pull starting gets the engine rotating speed to 1-2k RPM or more. The starter can only do about 200 RPM with a good battery if you're lucky. If the engine has low compression, pull starting overcomes this were the starter cannot.

 

^^^What he said. Losing compression will first exhibit as sluggish or unable to hot restart. This is due to expansion of the housings which prevent the side and apex seals from forming good vacuum on intake and compression prior to ignition. If you let the engine cool completely, then it starts fine, it's bad compression, and a rebuild will be needed. Eventually, it will get to the point where it won't even start when cold, as the seals are just worn too far. At this point, pull starting with another vehicle will work to get it running, but you're on your last legs.

A compression test will tell you everything you need to know.

 

Thank you! I will get ahold of a tester, after today if testing my starter sounds very sad and weak so I will be replacing that at the same time.

 

Were it mine I'd try putting an ounce or so of 2 cycle oil in each carb. venturii, turn the engine by hand for a few rotations and see if that eill get enough sealing to start. Poor man's compression test.