EFI distributor tester

[FB71]

ok, many folks over the years have had trouble with their beloved Festies not starting, or dying while driving. One of the possible failures is the distributor. I have devised a simple distributor tester.

It consists of the following components:
one 9V battery
one 9V battery clip
one LED, your choice of color. Just make sure it operates on 1.5 - 2.5 volts. 3.2v LEDS will be dim, unless you change the resistor value to 350 - 390 ohm.
one 1/4 watt resistor, 470 ohm (for 1.5V - 2.5V LEDs)
one distributor 3-wire connector from a junkyard Festiva.

Follow the wiring diagram below.

To test a distributor in the car;
this method assumes you have checked to see the timing belt is not broken, and the distributor turns while the engine is cranking.
Unplug the distributor connector from the distributor. Plug in the tester. Have an assistant crank the engine. Look for the LED to flash as the engine cranks. If it does flash, the distributor is good. No light or light solid = bad distributor.

To test out of the car;
connect tester to the distributor, turn distributor shaft by hand. Look for the LED to flash. Results same as "in car".

[Biglay5150]

Thats Awsome!!

[JPT]

Good sticky worthy info!

[MONSOON]

Great stuff Jim! I hope you dont mind I saved the write up and diagram. If it ever comes up again and we cant find this thread or whatever. Ive got it for others.

[milehighbear]

I just knew you were more than a pretty face on here, good job

[deathegg]

genius |ˈjēnyəs|
noun ( pl. geniuses )
1. exceptional intellectual or creative power or other natural ability : she was a teacher of genius | Jim has an amazing ability to diagnose Festiva problems.

[jglutz]

Sweet

[blkfordsedan]

Great idea! Just one question...is the module either "good or bad" or can it be weak/intermittent? My '93 has a very slight repetitive surge to it under acceleration. First thought was a dirty fuel filter but the fuel system all checks out and I noticed an occasional rough idle and the tach needle sometimes wigs out. Wondering if the module is the problem. (Other thought is an HLA that is weak or TPS).

[deathegg]

Also, is this for EFI cars only as the title says? Or would this work for carb cars like my '88?
Thanks.

[FB71]

Also, is this for EFI cars only as the title says? Or would this work for carb cars like my '88?
Thanks.

this is for EFI cars only, at this time. The module in the carb dizzy carries the full amperage of the coil, and will require a different test method for accurate results.

[ejp2fast]

thanks!!

[FB71]

Great idea! Just one question...is the module either "good or bad" or can it be weak/intermittent? My '93 has a very slight repetitive surge to it under acceleration. First thought was a dirty fuel filter but the fuel system all checks out and I noticed an occasional rough idle and the tach needle sometimes wigs out. Wondering if the module is the problem. (Other thought is an HLA that is weak or TPS).

this is a "Go / No Go" test. Heat from operation can cause intermittent failures to be exposed, but the tester would have to be connected at the time of failure to detect it.

[FB71]

Great stuff Jim! I hope you dont mind I saved the write up and diagram. If it ever comes up again and we cant find this thread or whatever. Ive got it for others.

no problem! Glad I could post something of value!

[packrat427]

It really is sweet !!!

I have seen it work in person !!

PM sent Jim ..

[Mike McKown]

I made one. It works. Great little tool. Thanks.