1982 70hp Johnson seahorse, occasionally wont run under load!!

[Stoycos]

Hi, i recently bought my first boat with a 70 hp johnson, runs great on the hose, and under idle. But when i tried to put load on it at the dock, it would cut out after putting the throttle about 1/2 way. Once i ran it on the water, the problem seemed to stop and it ran fine. Then i pulled it off plane, and it did the same thing!!!! after struggling with this for about 15 minutes,the boat finally seemed to jump into higher rpm's, and ran fine, i rebuilt the carbs, replaced the gas lines, and put new spark plugs in, still the problem persisted. Also, pushing the choke seemed to have no affect, any help would be greatly appreciated!

 

[mekkamaz]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

What about fuel pump? have you rebuild/replace it? And the priming bulb..it is firm or soft when the issue is present?

 

[Stoycos]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

The bulb is rock hard (which it wasn't before i replaced the fuel lines), thats the next thing to do, but i was was wondering if it could be the coil?

 

[Stoycos]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

And the problem with it being the fuel pump is that it works sometimes and not at others! Im stumped and being only 15 have limited knowledge!

 

[mekkamaz]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

Could be the power pack or a coil. but a simple test is when it fails pull the plug wires and check for spark to identify the one who has the issue, swap coils and if the problem follows the coil voila!..beware of the high voltage, use isolated pliers or something but a good hit will feel somewhat like sweet learning! LOL!

 

[Stoycos]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

Haha i would not enjoy that! could i use a timing light instead??? and is there any way to check the fuel pump besides rebuilding it?

 

[mekkamaz]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

Yeah, that?s the better way, timing light..r u sure you?re only 15? huh! read a few yourself right? Ok! Try isolate the issue to ign or fuel, as with the timing light and for the fuel pump you can prime the bulb when the problem is present, then if it kick back up, then is a fuel issue...

 

[Stoycos]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

Haha yah! well i think i found the problem, the compression is good, and the spark is good, really all i need to do is synchronize the linkages, and replace some small gas lines that have seemingly caved in!! Do you know of a way to synchronize the linkages?

 

[mekkamaz]

Re: 1982 70hp Johnson seahorse, occasionally wont run under load!!

Well, at this point you have to get a Service Manual for your engine. Also it will save you some time and money ahead.
Good luck!