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Crusader 8.1L compression test?

E

erich

Regular Contributor
What is the correct procedure for doing a compression test on an 8.1L EFI engine? On an engine with a distributor you would disconnect the high voltage center wire at the distributor and ground it. Since this EFI engine has coils for each cylinder, should I just disconnect the spark plug wires and let them hang loose, remove all plugs, open the intake by putting the throttle up all the way, and proceed to test the compression on each cylinder?? Should the fuel valve be closed also? I can not find a procedure online.

Thanks,

Erich
 
Erich, I would not let the spark plug wires just hang because you'll want the high voltage to discharge upon each cycle.
I'd find a way to disconnect the power to the ignition system.
You may also disconnect power to the fuel pump.

The test gauge will be somewhat accumulative for the first cycle... so be sure to cycle each cylinder a minimum of three compression strokes (six or seven crankshaft revolutions).

Doing the compression test with the air valve/butterfly fully or partially open simply provides the least incoming air resistance.
As long as there is little to no resistance at cranking RPM....... the test will be accurate.


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fastjeff said:
Have the bilge blowers running, and be sure to ground the coil wire to the block.

Jeff
Click to expand...

What coil wire? I believe there is a coil for each individual cylinder. Should I just disconnect the ignition coil harness on each side of the engine?
 
Docksidemarineservices said:
Leave the ignition turned off and just jump the slave solenoid. THAT IS ALL.
Click to expand...

The parts manual for the 8.1L engines shows engines with a serial # before 630396 with the slave solenoid and those above 630396, like mine, without it. I will take a look but I don't think my engines have one. If not, can a remote starter be connected in a similar way to the older carbureted and distributor type engines? I have a 3 wire one I used on my previous boat with 454s. It would connect to the starter solenoid, the coil, and battery. It has two switches on it. One would turn on the ignition similar to the key at the helm, and the other is a spring loaded rocker switch to engage the starter. If I didn't turn on the ignition it would just crank the engine without starting, which is what I need now.

Thanks,
 
If using a remote start switch can be done while simultaneously disabling the ignition system and the fuel pump system........ I would think that you'd be ok!


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RicardoMarine said:
If using a remote start switch can be done while simultaneously disabling the ignition system and the fuel pump system........ I would think that you'd be ok!
Click to expand...

Rick,

If I go direct to the starter motor and crank the engine from there, why would it be necessary to disable the ignition and fuel pump? I will only be using the remote starter with a connection to the battery and starter solenoid.

Thanks,
 
Careful! Motors with ballast resistor ignitions will still start up with the key off if you jump the solenoid. (Don't ask--please!)

Jeff
 
fastjeff said:
Careful! Motors with ballast resistor ignitions will still start up with the key off if you jump the solenoid. (Don't ask--please!)

Jeff
Click to expand...

Aren't ballast resistor ignitions old school? I am talking about a 2003 8.1L Crusader engine with multi-port fuel injection.
 
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