compression test on a 85' 150 johnson

[chuck1443]

is a compression tester for a boat same as a car ? how about spark tester? sorry if this is a silly question i would like to fix this boat myself (with your guys help ) and from what ive read thats where i need to begin

 

[JB]

Re: compression test on a 85' 150 johnson

Hi, Chuck.

Go to the top of this forum and look in the Top Secret File for instructions on Compression Testing (same guage you use on your car).

We can help you fix your outboard, but you gotta tell us what is happening/not happening.

Let us know, and good luck.

 

[chuck1443]

Re: compression test on a 85' 150 johnson

thanks jb

 

[chuck1443]

Re: compression test on a 85' 150 johnson

i want to think its the primerball because it wont pump hard and the inline filter (clear) fills only half way or even with the inlet - outlet hoses

 

[emdsapmgr]

Re: compression test on a 85' 150 johnson

It's easy to check for spark when cranking (or when the engine is running) with an automotive-type inductive timing light.

 

[jonesg]

Re: compression test on a 85' 150 johnson

Start by telling us exactly what the problem is.
And give some background on the engine, symptoms...
is it new to you? did it run good previously etc ?

 

[chuck1443]

Re: compression test on a 85' 150 johnson

yes its new to me and it ran last fall my freind had it on the ohio river, i heard it on muffs 2weeks ago, i took it out thursday and could'nt get it up on plane. The lake was rough and up so i probably rushed the warmup so i dont know if it would idle smoothly. i just learned the proper way to start the boat on this site. Useing the choke to keep it running would kill it, and pumping the ball did'nt help. It would throtle up in neutral but would not it gear. The primer ball would not get firm at any point. i got a compession and spark tester yesterday an im going to check to see what they are today.

 

[chuck1443]

Re: compression test on a 85' 150 johnson

thanks for your help

 

[chuck1443]

Re: compression test on a 85' 150 johnson

i found the primer ball had a air leak (cheap plastic inlet -outlet connectors) but i have another question the fuel return line on the fuel line connector is pluged off and the return is going back to the fuel pump is this ok

 

[jonesg]

Re: compression test on a 85' 150 johnson

The bulb doesn't stay firm once the engine is running. Thats normal.
I think you'll find its not running on all cyl's, the spark tester will show whether its ignition or , by default, carbs.

 

[chuck1443]

Re: compression test on a 85' 150 johnson

i understand the bulb does'nt stay hard but shouldnt it begin hard and if its leaking air wouldnt that cause it not to run right

 

[emdsapmgr]

Re: compression test on a 85' 150 johnson

If you have an "air leak" you should get fuel spraying/leaking out from that area when you prime the bulb up to hard. The bulb should go hard when primed. Once the engine starts and the pump starts to draw fuel, the bulb will get softer, but should not collapse.

 

[chuck1443]

Re: compression test on a 85' 150 johnson

just ck the comrression (cold) & spark not good 90-90-95-90-95-no 6 had 70 spark alot less than 7/16 and spuratic. now what can i do? spark plugs were also wet with oil

 

[boobie]

Re: compression test on a 85' 150 johnson

# 6 could have stuck rings or a blown head gasket or worse. You also have a spark prob. Did you check the spark with the plugs out ? Drop the gap to 3/8 " once and see what happens.

 

[emdsapmgr]

Re: compression test on a 85' 150 johnson

Instead of continuing to work on a fuel or spark issue, you need to find out why the compression is so low on #6. 70 is way out of normal tolerance limits. [normally a 10% variance is acceptable] I doubt a routine decarb will bring the compression up 25 lbs. To be prudent, best to pull the head off. Once you get the head off you can see if the head gasket seal ring is intact. If the head gasket seal is not blown, then you have some other major issue in the powerhead. Check to see if the top ring on #6 is in one piece and if there is any aluminum transfer onto the cyl walls.

 

[chuck1443]

Re: compression test on a 85' 150 johnson

no the plugs were in ,it wasnt a consistant fire thats while running ,cranking was alot worse almost wasnt firing

 

[jonesg]

Re: compression test on a 85' 150 johnson

I'd give the low cyl a blast of seafoam to decarb it, could just be a stuck ring, let it soak an hour and retest compression.
If it does come up a bit do it again.

If it doesn't come up pull the head.
The ignition is less of a problem, fix the mechanicals first.

 

[chuck1443]

Re: compression test on a 85' 150 johnson

ok i will, how moch seafoam, and should i warm it up before checking? you guys are great thanks for your help

 

[jonesg]

Re: compression test on a 85' 150 johnson

http://forums.iboats.com/showthread.php?t=299680

 

[chuck1443]

Re: compression test on a 85' 150 johnson

my freind offered my money back to return the boat to him ,if the decarb doesnt work what kinda money would i be looking at? its probably best to give it back