(Hopefully) simple question about a fuel pump.... **Mounting pics added**

[mark in new jersey]

Converting my '53 Super Fastwin from double hose to single, I was told that this was a great pump to use.

It came with no instructions......I guess I'm supposed to just know, but I don't:

of the 3 barbs....."A" - big plastic, "B" - small brass, "C" - big brass,

Which barb is "fuel in" from the tank
Which barb is "fuel out" to the carb
Which barb goes to the manifold to make it work?

Anyone know?

 

[F_R]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

A= Fuel in
B= Fuel out
C= Pulse

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

Final answer?

(just kidding...thank you!)

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

another question: can "A" be re-oriented?

 

[Haffiman]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

A may be re-oriented to whatever way you like, but is recommended to keep it pointing down. This will avoid creating an air bubble on top on the suction side.

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

good to know....thanks!

Interesting that, if it should be pointed "down", it comes from the factory pointing up.....

 

[Tim Frank]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

Then you have reoriented it. The "V" on the pump body should point up....i.e. the plastic fitting is correctly positioned now.

That plastic fitting is removable by unscrewing the captive screw in the centre; the fuel filter screen disc is accessible for cleaning when it is removed.

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

V pointing up.....that's very cool to hear, because that's what I did.

there's not a ton of real estate on this old 15HP, so I have to get creative. I made an aluminum plate which mounts on top of the bypass cover (using slightly longer screws to get full thread-purchase into the block), then from there I mounted the pump (V up) in such a fashion that it doesn't interfere with the cover mounts, et. al.

Pics, if you're interested....

Rough fit of the plate...

Finished plate, with longer screws through the bypass plate and long screws for the pump.....all in SS

Pump mounted!! And there's still room for everything else, including the cover.

I will draw the operation pulses from the lower bypass cover; I will drill out the center hole in the casting & tap it 1/8NPT, mount a nipple & connect to the pump w/ hose.

Still miles away from this being an engine, but we're getting closer!

 

[kfa4303]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

carb and fuel pump in one day. gettin' close indeed!!!

 

[Tim Frank]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

I will draw the operation pulses from the lower bypass cover; I will drill out the center hole in the casting & tap it 1/8NPT, mount a nipple & connect to the pump w/ hose.
Still miles away from this being an engine, but we're getting closer!

Get the fitting before you drill/tap.
I think it needs to be 1/4" NPT...you need to match the size of nipple C.

 

[HighTrim]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

...and also silly point, but will mention it none the less, take the bypass cover OFF before drilling and tapping!

I realize this is common sense but have seen it done before.

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

thanks.....but I'm "not one of them". The cover will be removed & all drilling done on my drillpress.

1/4" NPT? Yikes! No way there's enough material in the cover to support 1/4" NPT. Are you sure? That throws a serious crowbar into my design ideas.....

EDIT: actually, it looks like I can get 1/8"NPT to large barb, no problem...
http://www.plumbingsupply.com/barb.html

 

[HighTrim]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

Yup 1/4"....Seems thin eh, but there is enough there.

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

That's 2 votes for 1/4" NPT, and to be honest, I'm at a total loss to understand why....

The barb on the pump measures ID of 0.186" (i.e. 3/16").......no doubt I can see why you wouldn't want to drive it with a lower diameter hose, for fear of starving it.

(I'm new to outboard engine rebuilding, but I'm very familiar with mechanical engineering & fluid dynamics)

So the barb is 0.186" ID.....but so is the ID of the body of a 1/8"NPT fitting, as shown here. Actually, it's a smidge bigger at 0.188"

In other words, both fittings are 3/16" ID.

(Note: I know this barb in the picture is too small, and I don't suggest using it.....I'm just showing the ID of a 1/8" NPT fitting....)

Since I can buy a ***1/8"NPT - to - 3/16" barb*** fitting, and since the ID will be about 3/16" the whole run, what's wrong with using a 1/8" NPT fitting in the bypass cover?

I defer to your knowledge of outboard engines, but my day job experience with fluid dynamic engineering prevents me from understanding why you guys are saying to use 1/4" NPT.....

What am I missing? Help!

 

[Haffiman]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

With the sharp bend you get on the puls hose, use a spring inside to prevent it from collapsing.

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

my hose won't have any sharp bends

 

[laderwell]

Re: (Hopefully) simple question about a fuel pump.... **Mounting pics added**

here is a pulse limiter threaded and block fitting that I have extra from my VRO pump , the I.D. is 3/16th's, send me your address and you can have them

 

[mark in new jersey]

Re: (Hopefully) simple question about a fuel pump.... **Mounting pics added**

I appreciate the offer, but I have tons of barb fittings like these. My question / concern is "Why am I being told to use 1/4" NPT?" when 1/8" seems to be more than sufficient......

(Interesting that your picture looks to be 1/8" NPT....)

 

[laderwell]

Re: (Hopefully) simple question about a fuel pump.... **Mounting pics added**

I dont know , your going to have to go with your instinct.

 

[Tim Frank]

Re: (Hopefully) simple question about a fuel pump....

Re: (Hopefully) simple question about a fuel pump....

Get the fitting before you drill/tap.
I think it needs to be 1/4" NPT...you need to match the size of nipple C.

This response seems to be causing OP some concern....
Let me rephrase:

I would suggest that you FIRST get the proper size and type of hose that will fit Nipple "C".
Then get the fitting that will fit that hose and thread into the hole you plan to drill and tap.
Then drill and tap to match that fitting.
1/8 might be OK for Nipple "B" , but "C" is bigger.

You seem to understand exactly what you have to do, so don't pay too much attention to advice from the cheap seats.....

I was just emphasizing the advantage of making sure you worked from the parts that you are able to get rather than just tapping to a size and trusting to the inventory gods that what you wanted to install was available....and then finding the part is not available....:facepalm:

If you can get 3/16" NPT stuff, fine, but it is not standard...... around here I'd likely have to use 1/4".