Johnson 1978 175 v6 carb question

[peter1147]

removed all jets from carbs x 3
idle orifice nos 33,33,31,30,30,32,31. is this right that they are not the same
omc book ref 32 slow jet all?
my main jets are 34 x 3 correct by manual
reason for carb overhaul poor slow running
just removed plugs 1 and 3 oily==33 in 1=33 in 3=
rest ok ( what should I run with in idle orifice jets)

thanks for advice
removed idle jet blanking covers and cleared
now runs!!!!!!!!!!!!
thanks all again

 

[emdsapmgr]

Re: Johnson 1978 175 v6 carb question

Suggest you run the factory recommended jets in the carbs. Check the compression on each cyl-low compression will affect idling and running. You don't want to put money into an engine with bad compression. Idle issues can be improved if the engine needs to be decarbed. The idle timing could be set too low. Check to make sure that all carb butterflys are completely closed at idle. If any fuel has dried up in the idle passages of the carb bodies, it will absolutely affect idling. You may need to clean out these passages with an aerosol carb cleaner. Check to make sure the cleaned passages will flow carb cleaner equally from one carb to the other.

 

[peter1147]

Re: Johnson 1978 175 v6 carb question

compression 120 all cylinders,carbs rebuilt,factory idle jets are 32,s 6 of
fitted jets will not start?
why did it have and assortment of idle jets in it and it ran?

 

[emdsapmgr]

Re: Johnson 1978 175 v6 carb question

It is not unusual for different carbs to have different jets in the same engine. The factory jets them differently to compensate for heat/exhaust temps, as each piston heats differently due to the exhaust system charges/pulses. On some later looper engines, the bottom two cyls even have lower compression than the top 4. It all related to making the engine durable.

 

[peter1147]

Re: Johnson 1978 175 v6 carb question

have fuel in carbs but plugs are dry?when trying to start with choke on
all carb channels are clear,jets are new
any ideas?

 

[emdsapmgr]

Re: Johnson 1978 175 v6 carb question

Is the choke solenoid closing the choke butterflys on the carbs? Make sure it is adjusted to fully close them. My 79 200 only had choke butterflys on 2 of the 3 carbs and it was a little difficult to start. Does the engine have good compression: around 110 lbs? Poor compression means the crankcase (carb) suction will be low also.

 

[peter1147]

Re: Johnson 1978 175 v6 carb question

comp 120 all 6, choke working on 2 as it should,pumps rebuilt, if we spray fuel in through carbs will run,then stops will not start or run,carbs rebuilt
any ideas?????????

 

[Pokertrampp]

Re: Johnson 1978 175 v6 carb question

Double check float adjustments

 

[gsyfishy]

Re: Johnson 1978 175 v6 carb question

Check the fuel lines on the bank of carbs that arent working, I mean check them good, pull them off and turn motor over, if you get fuel all the way to the carbs, then more than likely something got in their,

 

[emdsapmgr]

Re: Johnson 1978 175 v6 carb question

Will it run normally if you constantly prime the fuel hose primer bulb? This forces extra fuel around the pumps direct into the carb bowls. Did you look at the filter/screens inside the two fuel pumps?