Johnson 1974 6 HP will not stay running unless priming

[amhippi]

Hi, I am a pretty new boat owner and do not know much about outboard maintenance but am not lacking in mechanical inclination. I have a 1974 Johnson 6 HP Seahorse. This motor was given to me by my father who I know basically rebuilt it and got it running well according to him. Cleaned the carb, fuel fitler as well I am sure. The motor looks immaculate and has new plugs and lines it would appear. It sat in my basement for 3 years with no boat to go on and it was empty of fuel that whole time. I pulled it out this year as I finally bought a small fiberglass fishing boat to put it on and it fires right up in a couple pulls every time. However, it will not stay running unless you periodically prime the line about every 15 seconds or so. Adding to my confusion is actually the first time I took it out It died 3 or 4 times after starting and then ran just super for about 20 minutes of straight running. After I shut it down it went back to dying with out priming the ball. I have had it out a couple times since then and it runs, as long as you continue to prime the ball.

What I have done so far is not much trouble shooting other than getting new gas, with the proper mixture and additives for if the gas sits. When I bought the boat it came with a 4 HP I know needs the carb cleaned because it dies as well if not choked and unchoked. I do not think it is anything with the gas can, ball or lines because like I said the 4 HP I had runs without priming but has its own problems.

Where do I need to begin with this thing in diagnosing the problem with this? Also, anybody have an idea where I can find some engine diagrams? I am such a novice on this that I don't even know when looking under the hood at this thing where the fuel pump is if that is the issue. I am following the fuel lines and I would assume the first thing that is the lines run into is the filter, followed by the carb but after that I am lost (and I may even be lost there)

Thanks.

 

[raczekp1]

Re: Johnson 1974 6 HP will not stay running unless priming

hi.
with this 6hp model, clean filter screan located on fuel pump cover.if this doesnt help, buy fuel pump repair kit(SIERRA 18-7823-8,3$).
use good instruction how to asemble this pump :http://www.sschapterpsa.com/ramblings/Rebuilding_fuelpump.htm
buy new primer bulb and run your engin
drowings:http://www.crowleymarine.com/parts.cfm, pick evinrude or johnson, year and model by horse power
your model is:http://www.crowleymarine.com/johnson-evinrude/699.cfm

 

[Vic.S]

Re: Johnson 1974 6 HP will not stay running unless priming

It is obviously not pumping fuel.

It could be a defective fuel pump. In which case replacement or overhaul should solve the problem.

It is also possible that there is air being drawn into the fuel line. Anywhere from the tank to the pump but prime suspects are the fuel line connectors.

 

[amhippi]

Re: Johnson 1974 6 HP will not stay running unless priming

Thanks fellas... one more quick question. As I said I have this 4 HP and 6 HP... both Johnsons. The 6 HP is a 1974 and the 4 HP is a 1987. The fuel pumps look identical. Any thoughts on if they are and if I can swap the two for the purposes of diagnosis?

Thanks.

 

[tasroc]

Re: Johnson 1974 6 HP will not stay running unless priming

i have this same problem with my 50 evinrude. It wont stay running unless i manually pump it and then it only runs for about 5 min before the no oil warning buzzer comes on. how can i not be getting fuel or oil? My manual ball pump on my oil tank is hard as rock and cannot be pumped. I can shut it off and restart it as i wish for 5 min periods.

 

[amhippi]

Re: Johnson 1974 6 HP will not stay running unless priming

Well never mind my previous question, they aren't the same fuel pump. I am wondering if the lines on this thing aren't all the way tight. Initally when I prime the ball with the hood off a little bit of gas initially leaked out of the line right before the fuel filter. However, this was after I took the filter and pump off to see if the filter needed to be cleaned (which it sure looks clean as a whistle). However, it didn't leak after that first couple squeezes of the ball.

I asked my father if it was a new fuel pump and he said it was a new one so is there any other thoughts of what this may be if we assume the fuel pump is fine?

I suppose I will just start replacing hoses, primer balls, gas tanks all the way to the filter and pump.

Could it be something with the cylander pressure or worse?

 

[Vic.S]

Re: Johnson 1974 6 HP will not stay running unless priming

Thanks fellas... one more quick question. As I said I have this 4 HP and 6 HP... both Johnsons. The 6 HP is a 1974 and the 4 HP is a 1987. The fuel pumps look identical. Any thoughts on if they are and if I can swap the two for the purposes of diagnosis?

Thanks.

Well never mind my previous question, they aren't the same fuel pump.

All the old square type fuel pumps are basically the same ... just assembled to put the inlet and outlet connections in different positions ... see the link in raczekp1's post. If your two have the inlets and outlets in the same positions they should interchangeable without further ado. But I guess since they are different part numbers they are orientated differently.

You should be able to blow through them in the normal direction of flow ie inlet to outlet but not in the opposite direction .... again see Lee Roys ramblings. The inlet is always the cover over the filter the outlet is the other connection.

 

[amhippi]

Re: Johnson 1974 6 HP will not stay running unless priming

Thanks... I do believe it is the fuel pump since I can blow both ways through it. So, I guess a fuel pump repair kit should fix this sucker up? Hopefully I don't need an entirely new fuel pump since that looks to be about $100 as opposed to $8 for the repair kit.

On to my next question about cleaning the carburator on the 4 HP 1987 Johnson. I have it off, now what I am wondering. That is for a different post (unless you guys know some resources on how to do that one).