compression questions

[bobkyle2]

so i ran the compression on my 84 mercury 150
#1-121
#2-122
#3-119
#4-124
#5-121
#6-125

after i ran them i realized i didn't have the throttle wide open... it was in nutreal... would that affect anything... and if it would would it hurt the numbers or help.... i talked to my dad and he said the numbers sound good... what do you guys think...

i did the compression test because today when i put the boat in and it barely start... i had to keep cranking in till the battery's were almost dead but it finally started it was missing at idle and when i took off.... but it cleared up...it was also 69degrees today

when i pulled the plugs they looked gas fouled...(just replaced them about a month ago with ngk i believe the part number was BU8H) ...

another question does these motors an air filter....
after it cleared out it ran good but still felt like it was missing a little at idle

[Jay Smith]

No air cleaner... Compression looks OK .. Check for water in fuel .. Your running the correct plug for the engine. Battery has to also be HOT 12.5 volts not running and over 14 volts idleing at 1500 RPMs..There can be many things that causes the issue you describe start with checking the cheap thing to fix first. Grounds clean and made well , water in fuel, hot battery with good cranking amps etc...

Jay

[bobkyle2]

Thanks for the help jay...

My batterys are both new and its cranking fine...

i beleive i fouled my plugs some how..when i did the comp check they looked oily... but the plugs are only about a month old... i run 50 to 1 i premix my fuel...(oiler was taken off by previous owner)... i usually fill the boat up when it has around a half tank... my dad said that i could be mixing a little to steep sometimes and its just adding up... so i think im going to pump all the gas out and just start fresh...

I also noticed it looke like there was oil seeping out of my number 5 plug out of the porclin... so im going to add new plugs.. and see how that does...

Thanks alot kyle :D

[bobkyle2]

could someone explain to me what the bleed lines do.. my owners manual is at my camp... i think one of the bleed lines has been leaking oil... what do these lines do.. and would it be a good ideal to just replace them all.. and anyone know the size of line off the top of there head... so i could go ahead and get them before going to camp this weekend..

thanks for the info...

Sorry for all these newbie questions..... its not a small or big block chevy so i dont know schnit about it..:thumbsup:

[ChrisCarsonMarine]

The oil won't keep building up,your constantly using it with the fuel.The bleed lines are part of a scavenging system that disposes of puddled oil in the crankcase to improve idle quality and trolling,mostly,would not effect starting.Don't use fuel over 3 months old,today's fuel degrades fast,and can cause all kinds of trouble,also,use ethanol free if you can.Get the bleed line at merc dealer,it's special thick walled tubing specifically made for this purpose,replace the leaky plug,Chris

[bobkyle2]

i think one of these lines were leaking .... if one of those lines were leaking would that cause me any problems... ive gotten a little oil under my cowling and i think i seen some oil leaking from a line

Thanks alot Chris.. didnt figure anyone would be up and want to deal with my snuff this early;)

[ChrisCarsonMarine]

Unless your motor was really leaned out to the max the leaky bleed line won't do anything but possibly mess up idle a tiny bit,probably wouldn't notice.Change the lines,and try re-starting properly,trim all the way down,prime till bulb is firm,advance throttle a little,turn key to run,push choke for 3-5 seconds,while still pushing key in choking crank till start,if no start in 10 seconds,rest starter and try again.If that dosent start it there's something wrong,the cool temp,is not the problem,Chris

[bobkyle2]

Thanks chris....... someone else also told me i need to check my spark gap.. so i bought a tester........ and they said it should be 7/16's ... is that 7/16s of an inch??? and is that figure right..

[ChrisCarsonMarine]

The distance the spark will jump will vary greatly with cranking speed,with the plugs out and a hot battery you should see 1/4-1/2 inch gap jumped easily,if less than 1/4 somethings not right.Check and see,and report if necessary,both sides of the motor should be about the same,Chris

[bobkyle2]

ok thanks a million..... i got the ignition tester last night... :thumbsup:

[97 TWISTER]

If your not already make sure your motor is trimed down completely so the fuel goes directly into motor, just a thought.
Jerry

[bobkyle2]

well its trimmed down pretty far... same as i always have...its not completly down while trying to launch..down far enough tho.....Thanks for the advice tho :D

[bobkyle2]

ok...im about to buy a tohatsu ..or something...haha......... well put it in the river today...cranked and cranked and cranked.... the batterys started dyeing.... then the last time i tried starting it... it fired up.... missed really bad... backed it off the trailor and took off up river immediatly... missed for about 4 seconds.... cleared up... ran and started perfect all day... thats what it keeps doing now... the first time i try starting it gives me fits.... its got 2 new batterys... starter seems to operate well...its got an enricher choke.... im guessing its not working properly... i hear it click wen i push the key in... or any other suggestions guys .... Thanks...

[ChrisCarsonMarine]

See if it's passing fuel when you choke it,sounds like not,chris

[bobkyle2]

ok..... i found my problem...i think...i threw the valvoline away and... i had put a new primer bulb on it and i guess it was bad ..it was brand new... i tried my old one and its been firing right up..it fired up the other day at like 6am and it was very very cold out... fired right up and ran great even in the cold weather...i was surprised... i wouldnt suggest using that valvoline.. i hated it.. ...... Thank you all!!!!