Pressure tank to fuel pump?

[WEH]

I was looking through the posts and found a thread that alluded to installing a fuel pump on a 1950s vintage Johnson/Evinrude, the ones that use the pressure tank and double fuel line hose. I have never heard of this, but then I have never heard of a lot of things.<br /><br />Is this really feasible? <br /><br />If it is, what are the pros and cons? What powers it? What is involved to make the conversion (in general terms) and about what would it cost?<br /><br />Thanks,

 

[OBJ]

Re: Pressure tank to fuel pump?

Hey Cruncher...<br /><br />Sure it's possible and it works.<br />Look at the double hose system. One hose is connected to the block and the other to the carb. The one connected to the block is what puts the pressure in the fuel tank. Hook this up to a fuel pump and and BINGO, no more need for a pressurized tank. Fuel pumps, simply put, work off the pressure and vacuum of the block. A diaphram inside the pump works back and forth to draw the fuel up to the pump and then into the carb. Simple but effective.<br /><br />OBJim

 

[slow_boat]

Re: Pressure tank to fuel pump?

The Seloc manual for your year model has a brief description of how to do this conversion. OMC made a fuel pump that is commonly used to do the conversion. It is no longer made according to my research but they are occasionally offered on ebay. The pump you are looking for has 3 nipples instead of the normal 2.

 

[clanton]

Re: Pressure tank to fuel pump?

On some of these engines you could buy plate on side of engine that covers the ports, from later model engine, that had mounting boss for fuel pump.

 

[slow_boat]

Re: Pressure tank to fuel pump?

Thanks Clanton. From my research I could only find reference to conversion parts that used the plate swap as being available for the larger engines only. I read in another of crappie crunchers' posts that his engine was a 5.5hp. <br /><br />Let me know if these parts (the plate with the fuel pump opening) were available for the lower HP engines as I am curious.

 

[Hooty]

Re: Pressure tank to fuel pump?

I don't know if it would work or not but the present-day fuel pumps have three ports and are pulse operated. I wonder if you could mount one anyplace convenient and run the three hoses to it (pulse, fuel in and fuel out) and have it work?<br /><br />c/6<br /><br />Hooty

 

[slow_boat]

Re: Pressure tank to fuel pump?

Hooty,<br /><br />Sounds like the pumps you mention would work as long as the engine it is fitted to has enough pulse to overcome the spring tension on the diaphram. I bought an old pump that I am going to put on one of my engines but have been a bit hesitant until now to drill and tap my intake plate. I recently bought a frozen block of the same vintage & am going to use the plate off it to play with. All this after buying 2 pressure tanks that work great Just can't stop tinkering.

 

[Hooty]

Re: Pressure tank to fuel pump?

I just picked an engine at random. It was a '87 10hp and it even had what looked like a sheetmetal mounting bracket. I figgered just connect the diaphragm chamber to the pressure line that goes to the tank. I also figured that line has a check valve somewhere so it just blows and doesn't suck. Check valve would have to go so that pump would see pulses. Whadaya think?<br /><br />c/6<br /><br />Hooty

 

[clanton]

Re: Pressure tank to fuel pump?

The 5 1/2 does not have the plate on side of engine, like I thought. The pulse nipple on the engine that operates the double hose tank should operate a fuel pump. The double hose tank is not a pressure tank, it has a diaphram, check valves, and springs,just a pump buildt into the tank.

 

[WEH]

Re: Pressure tank to fuel pump?

The motor I am considering retrofitting with a fuel pump is a late 50's 7.5 Evinrude.<br /><br />What is the advantage to changing to a fuel pump from the pressure system? The only one I can come up with is if I don't have a pressure tank it may be cost effective to change to a fuel pump and have a better availability (and cheaper) of gas tanks, hoses and fittings.<br /><br />Also, what is the maximum practical lenght of fuel hose between the gas tank and the motor? I like to put my gas tank well forward in the boat for better weight distribution and to get the thing out of my way. Will a single line system with a fuel pump support a longer hose than a dual line pressure system?<br /><br />Thanks,

 

[Bear]

Re: Pressure tank to fuel pump?

Johnson Fuel-Master system kit 1959 (not for the 3 hp or 5.5 hp models)<br /><br />Btw, a picture of a 1958 Johnson 7.5 hp

 

[John Graves]

Re: Pressure tank to fuel pump?

Johnson Fuel-Master system kit 1959 (not for the 3 hp or 5.5 hp models)<br /><br />Btw, a picture of a 1958 Johnson 7.5 hp

I just bought a fuel pump that is used for this conversion. Mercury part number 89977A 1 $65.00. I know this pump works cause we have a mechanic that does the conversion. Evinrude doesn't make theres any more so this part is now being used. I'll let you know how it works. It has the three connections. one for the vacuum and presure, one for fuel in and one for fuel out.
catch ya later

 

[Lion hunter]

Re: Pressure tank to fuel pump?

Read this link


http://www.sschapterpsa.com/ramblings/Converting_dual_fuel_line.htm

 

[jbjennings]

Re: Pressure tank to fuel pump?

The 5 1/2 does not have the plate on side of engine, like I thought. The pulse nipple on the engine that operates the double hose tank should operate a fuel pump. The double hose tank is not a pressure tank, it has a diaphram, check valves, and springs,just a pump buildt into the tank.

The nipple on the intake only pushes air into the tank. The check valves are under the intake manifold, and a simple fix is required to change the check valve set-up to make a pulse vacuum instead of pushing air only. I haven't seen all of 'em, but I've seen quite a few, and have never seen a double line tank that wasn't a pressure tank, and never seen one that had a pump built in the tank. As far as I know, it doesn't exist.
Just trying to help clear things up on the pressure tank,
JBJ