1988 50hp force us marine out board bottom cylinder not getting gas

Dillybug1994

Recruit
Joined
Jul 11, 2015
Messages
2
My bottom cylinder is not running it has spark and compression but seems to not get gas the top cylinder runs when I pulled the cap it shuts off if I pull the bottem one it still runs I have no idea what to look for or do again it has spark bottom cylinder
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,605
:welcome: Dillybug1994, great to have you aboard...

After looking at the breakdown for your engine, I see it is a two cylinder one carb configuration. So that fact that the top cylinder is getting fuel and running, I think your problem could be actually spark. I understand you stated you have spark on both cylinders, but does the lower spark coil actually jump a 7/16" gap. Buy a spark tester at most any auto parts store and retest the spark again. And if your lower cylinder is not sparking via the tester setting, swap the spark coils and see if the problem follows the swap. If so, you have a bad spark coil... Post your results so we can offer more assistance... JMHO!
THX-404.jpg


This is a typical spark tester sold in the auto parts stores for a really cheap price... :thumb:
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,909
If you can attest there is actually spark on the bottom cylinder, then the next test is to find out if gas is actually getting into that cylinder. Remove the spark plug on the bottom cylinder, activate the kill switch (to prevent starting the motor and shutting off sparks) and crank the motor about three to five seconds while holding a paper towel infront of the bottom cylinder plug hole. Is there any sign of fuel or water being sprayed over the paper towel? Let us know. If there is no water nor gas or if there is gas but very little, then the bottom reeds could be bad. If there is a lot of water, you might have water intrusion from the exhaust plate.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
18,183
Usually if the tops getting fuel, so's the bottom.
Look someplace else for the trouble.
Do a compression test FIRST before you do anything else.
Then swap the coils around and see if the problem follows the coil.
 
Top