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1979 Johnson 15 HP Diagnostic help - Fuel Issue?

T

Tbonex10

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I have a 1979 Johnson 15 HP outboard. Today, I went to take it out, and it didn't make it 100 yards from the launch. The engine cut off like it was starved of fuel. I was able to pump more fuel with the hand pump, but again it died shortly after. I found out I was able to keep it from dying by using the hand pump to add more fuel when it started to sputter. I am wondering if I need a new fuel pump, like the ones I have seen on amazon for ~$20.

I took it home and swapped tanks and fuel lines, and with both variables changed I had the same issue.

This is the 5th time I have taken the motor out. It was my grandfathers, then passed to my uncle about 10 years ago, sat in a garage, and he gave it to me last month. All other times it has operated fine. This was, of course, the first time I took my wife out with me.

I am not very mechanically inclined but trying to learn. Any input helps. Thank you!
 
racerone said:
I would install a new factory diaphragm in that simple pump.-----Possibly an issue with fuel tank / hose as well
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Thank you for the reply. I am hoping to have time to tinker with the pump this weekend. I swapped the tank, and then swapped the hose with a new hose on the new tank, and still had the issue. That would rule out a bad tank/hose, right?

I will update once I repair/replace the fuel pump.
 
Issue is a classic failed fuel pump (it runs if you pump the hand primer).

FWIW, I've purchased those Amazon pumps before and for the same price (or close to), do what Racerone said and buy the factory (or Sierra) rebuild kit. It's really easy especially with some long screws to use as guides and keep everything in place. Once you've done one, you'll realize how easy it is to do.
 
Hey guys just wanted to update. I purchased a new fuel pump and installed it. The engine idled for about 15 minutes before I had to leave and work on other products. I did notice that when I got back to the boat there was a bit of brown oil/water mix discharge under where I ran the engine. I'm hoping it is just rich exhaust, but I will be keeping an eye on gear oil levels.

I took apart the one on the motor already and it did look easy to repair.. Also the part originally on my motor did not face the same way as the correct OEM part. I guess at some point it was repaired with an incorrect filter.

Thank you for your help! Happy to have it running again.
 
Tbonex10 said:
Hey guys just wanted to update. I purchased a new fuel pump and installed it. The engine idled for about 15 minutes before I had to leave and work on other products. I did notice that when I got back to the boat there was a bit of brown oil/water mix discharge under where I ran the engine. I'm hoping it is just rich exhaust, but I will be keeping an eye on gear oil levels.

I took apart the one on the motor already and it did look easy to repair.. Also the part originally on my motor did not face the same way as the correct OEM part. I guess at some point it was repaired with an incorrect filter.

Thank you for your help! Happy to have it running again.
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Glad to hear, what you saw after is just unburnt oil.
Not quite sure what you mean by "part originally on my motor did not face the same way as the correct OEM part" but I'm guessing it has to do with the direction in which the inlet and/or outlet of the fuel pump were facing. This is different on different motors. If it's the direction of the inlet the screw holding it in place can be loosened and it can be rotated. If it's the direction of the outlet, then the fuel pump needs to be taken apart and rebuilt in order to change its location.
 
JohnnyGuy said:
Glad to hear, what you saw after is just unburnt oil.
Not quite sure what you mean by "part originally on my motor did not face the same way as the correct OEM part" but I'm guessing it has to do with the direction in which the inlet and/or outlet of the fuel pump were facing. This is different on different motors. If it's the direction of the inlet the screw holding it in place can be loosened and it can be rotated. If it's the direction of the outlet, then the fuel pump needs to be taken apart and rebuilt in order to change its location.
Click to expand...
That seems so obvious in hindsight, but yes, I would just have needed to rotate the inlet valve by unscrewing it and it would have worked without me relocating the fuel line.

Thank you
 
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