compression test question???

[couchise]

i have done a compression test on my 85 hp force 1987, when i did my test i pulled out one spark at a time and did the test from the ignition. I have a landyard but i dont have to use anything to try and start the motor so i think it is unhooked. is this a bad way of doing the test haven't noticed anything different.

 

[jerryjerry05]

Re: compression test question???

You need to remove all the plugs and then do the test.J

 

[Frank Acampora]

Re: compression test question???

All three plugs need to be removed to do a compression check. The ignition needs to be off, and you run the starter by "jumping" from the red battery lead on the soleoid to the small yellow lead on it.

Some people like to have the throttle fully open but since these engines go to atmospheric pressure when the ports open, it is not necessary, the throttles can remain closed, and will not change the reading. The slight gain in cranking speed with the throttles open will also not affect the reading.

 

[couchise]

Re: compression test question???

thank you for the quick response you guys are aweosme.

 

[couchise]

Re: compression test question???

what yellow wire are you talking about, i see the big red one and then there is a yellow one going to the switch where the button is for the ignition to start on the other side of the motor. and do i use normal jumping cables for this coming off the battery.
thanks

 

[metor99]

Re: compression test question???

What is the differance weather you have all plugs out or only the cylinder of the compression test being done? The ignition power off, you just dont want the motor to start correct.

 

[couchise]

Re: compression test question???

the first time i did a compression test i had the tester n one cylinder and the ther two hooked up to the wires and spark plugs and got 115,125,125......this time i did it with all three out and the readings were as follows 120,125,125.
both time i used the ignition to turn it over and nothing happened to my coils.