Fuel Pump Conversion on 1957 Javelin - Help

[lew-anderson]

I read the post at

http://forums.iboats.com/showthread.php?t=205628

and have a couple questions about the conversion. I'd be delighted anyone can help clarify the best approach to take.

Question 1:
In the post listed above the conversion was done on a 1958 Johnson 35 HP. The listed pump used was the sierra 18-7351 fuel pump. The box on that pump lists it as for the 9.9 and 15 hp motors but I see the barb on the discharge is the same size as is on the carb on my 1957 35 HP motor. The difference between the 18-7351 pump and the 18-7352 is just barb on the discharge - right? And since the carb has the smaller connector the pump with the matching connector (the 18-7351) will work just fine - right?

Question 2:
I got a single line connector for the fuel tank connection to the motor but the fuel hose that attaches to the barb on the back side of this connector and then runs to the fuel pump is larger than the two holes that were in the shroud for the 2 line system. What should I do for the fuel line between the connector and the pump? It also looks like the barb on the inlet of the pump is even larger than this larger line on the single line fuel connector - what's the deal there? Is there a different connector I should get that has a smaller barb on the back?

I'd hate to drill the shroud.

I've attached attached a photo of the connector.

Many thanks if anyone can point me in the right direction.

 

[soundchaser]

Re: Fuel Pump Conversion on 1957 Javelin - Help

with the single line system, Yes the incoming line from the fitting you show has always been bigger. Probably to protect it from getting sucked closed. You do have the right fitting there. So you're going to have to figure out a way to get it to fit. I've done a couple of them years ago and I do remember having problems there. Maybe you could just rat tail file a prescribed amount out so it'll fit?

 

[jay_merrill]

Re: Fuel Pump Conversion on 1957 Javelin - Help

You can do this ...

... or you can do this ...

In the first photo, I used a bypass cover off of a Johnson 33 hp engine. That bypass cover has the drilled/threaded bosses that you need to install a stock OMC fuel pump. Notice that the pump is rightside up and that the top of the pump clears the throttle control rod above it.

The second photo shows an original bypass cover being used. Since that cover has the bosses, but they were not drilled/threaded, I had to drill all three (middle one all the way through for vacuum/pressure pulses) and thread the outer two. In this case, however, the pump is mounted upside down. The reason for this is that the older bosses are moulded into the cover, in a very slightly higher position than on the later covers. If you use the fuel pumps that I did, in a rightside up position, the top of the pump will hit the throttle control rod in a portion of the rod's normal travel.

Both of these engines are 1958 ERude Bigtwins. I ran both this way for several years without problem. I mention this, because some people have tried to convince me that these pumps will have problems, if they are run upside down. The one that I mounted that way worked fine.

BTW, the red wires that you see are leads for the Tiny Tach tachometers that I used on these motors. My main purpose for having them, was to "marry" the throttles at cruise settings. While you can get pretty close to achieveing matched rpm just by ear, the tachs just made life easier.



???

 

[1946Zephyr]

Re: Fuel Pump Conversion on 1957 Javelin - Help

so there you go.....just buy the components from a 33hp and you're set. The 33 is identical to the older 35, except the head and the engine shroud.

 

[tmcalavy]

Re: Fuel Pump Conversion on 1957 Javelin - Help

And when it comes to hoses/sizes, you have to experiment...the hose should grip the barb/fitting tightly. Invest in ethanol resistant hoses, too...to safeguard your equipment. The other option is using a Mikuni fuel pump. I have a 57 E-rude Big Twin rigged that way and it runs as good as its 57 Johnson mate fitted with a factory OMC fuel pump...takes one extra squeeze on the primer bulb to push fuel through the Mikuni to the carb, that's the only difference I have noted.

 

[lew-anderson]

Re: Fuel Pump Conversion on 1957 Javelin - Help

Thanks guys for the help.

With those suggestions I can see I'm heading in the right direction. It's good to know I can mount the pump in either orientation - provided it doesn't bump into anything.

I was able to push the larger fuel line from the connector onto the inlet barb on the fuel pump - so that issue is solved.

My big remaining question is how to route the larger fuel line from the fuel connector to the fuel pump. I've attached photos of the existing two holes from the previous fuel line which are too small for the single fuel line (yellow arrow in photo). I've also attached a photo of a horizontal hole in the shroud that looks like it would work (blue arrow in photo) - but it's got some wires in it now. I'm guessing I could route the wires through the smaller holes and the fuel line through the big one. Has anyone tried that approach? I'd like to avoid drilling into the shroud so I can keep that part as original as possible. I could drill another hole where the red arrow is as well - I'd rather do that than drill out where the existing 2 holes are. Suggestions?

The other question is just to confirm that I should use the Sierra 18-7351 pump versus the 18-7352 pump. The outlet barb on the 18-7351 pump is the same size as is on my carb - so I'd have the same size fuel line with no adapters - but the box says it's for 9.9 and 15 hp motors. I've attached a photo of the two style pumps. The pumps look identical except for discharge barbs.

 

[1946Zephyr]

Re: Fuel Pump Conversion on 1957 Javelin - Help

It looks like 18-7351 has an outlet nipple that matches the one on your carburetor. That looks to take the same 1/8" hose as your original. As for your other line, you can actually get the bigger line to go through that hole in the shroud. You just need to apply a light coat of oil on the hose and it'll slide through slicker than snot on a door knob.