Assessing and possibly rebuilding an early 1970's Johnson 175hp outboard near Nowra

[Mutt]

Fellow Fishraiders,

My brother in law has a boat with an early 1970's Johnson 175hp on his farm down the south coast near Nowra. He was able to turn it over but didn't stay running, he was wondering if there was anyone local who could assess and repair this outboard. Please PM me as don't want to break site regulations. Thanks in advance!

[Geoff]

Taking it to a mechinic & saying we have a problem , please identify & fix if possible can cost a lot of $$$$ whilst he goes through the basic checks to isolate the problem. A number of these checks are not difficult & can be done at home

If the motor has been standing for a long period , runs for a short period then stops I suspect it is fuel.

Start with a compression test , the difference between cylinders should not be more than 10 psi. Even if it is , it's unlikely this will be cause of the problem. The test is mainly to check the general condition of the motor

On the basis it actually fires up & runs for a short period then the spark & plugs could , at this point be considered OK. However , depending on how long the motor ran , a component may be breaking down when becoming hot

If the fuel is more than 4 - 6 months old replace with new fuel. Do not use E10

Drain the carby bowls checking for water & flush through with the fresh fuel. Try to start the motor, if the problem remains then the problem could be in the jets. They need to be removed & cleaned.

However , before doing so , when the motor starts to fade pump the primer bulb forcing fuel through the system . If the motor picks up then it's a fuel problem either in the pump or carby's

If servicing the carby's is not something you wish to tackle then have a chat to the local mechinics , there are several if I recall correctly in the Nowra area , & obtain a price to service the carby's / fuel system.

Geoff

[a boat]

Hi, good advice from Geoff and one thing for certain is it will not be a early 1970's 175HP Johno-it maybe late 70's so that is a bonus. As mentioned a carby service will be most likely required if a compression check or better yet a leak down test confirms the internal condition plus making sure you have 6 good sparks. If you have these and then nice clean fresh fuel from rebuilt carbies this 35 year old engine should start and run fine.

As for who to use, only one in Nowra would have any experience with such an outboard and he is the BRP dealer down that way. Not many people around today that has been in business as long as this engine has been around.

Cheers,

Huey.

[Mutt]

Once again, evidence why this is the best website, I tried to talk him into taking it to Cowan!!! I'll forward this information on and a huge thank you to both of you.

[Geoff]

One thing I forgot to mention . There should be a least one , if not two fuel filters , one between the tank & the motor , the other , just prior the the fuel pump. ( Huey may confirm)

If there is one prior to the fuel pump , these are normally servicable by removing & cleaning the filter.

The one between the tank & motor should be replaced.

In rereading your post , I suspect the primer bulb has been pumped until hard thereby pressuring the system.

Once the motor has started the pressure drops & a blockage somewhere in the fuel prevents sufficent fuel reaching the cylinders.

As mentioned previously , pumping the bulb when the engine begins to fade will confirm this one way or the other.

The other aspect to check is the fuel lines connections & clamps to ensure the system is not sucking air.

Geoff

Edited July 30, 2013 by Geoff