small 12v diesel pump for priming?

scenarioL113 · Post by **scenarioL113** » Mar 14th, '10, 20:14

I was wondering if installing a small fuel pump into the fuel system would be a bad idea.

I figure it could be used to prime the system and be installed near the fuel tank. When I fired my engines up after the rebuild I used this pump to feed the system from a bucket of diesel fuel and it worked great.

I think my manual lift pumps on the side of the engine dont really work that well and have been scratching my head about using the electric pump.
I was thinking about if it was needed I would have it plumbed into both fuel lines that go to port and starboard engines, this would be so I would only need one pump.

I am thinking of having a "tee" off of each pickup tube from the tank then to a shut-off valve for each side. the two feeds from each "tee" would then go to another "tee" to basically "Y" into the pump.
The output of the pump would "tee" off thru another set of shut-offs and back to the main lines respectively.

I know it sounds confusing but I am figuring that the electric pump should be isolated from the fuel supply when it is not in use and if needed you just need to open two closed shutoff valves and then activate the switch to turn it on.

Is this feasible or impracticle?

Frank

scenarioL113 · Post by **scenarioL113** » Mar 14th, '10, 20:33

This is a cheesey diagram I drew with paint but it visualizes what I am talking about.

The gray things are the "tee"'s red is starboard fuel line and blue is port. Green are the shutoff's. The purple line id the line that would be getting primed when the shutoffs are opened.

They would normally remain closed at all times unless needed. This entire idea would be manually used.

Bruce · Post by **Bruce** » Mar 15th, '10, 06:24

They way you have it designed it could potentialy just recirculate in a loop.

What you want is to add a fuel shut off in the main line between the inlet and outlet of the pump and shut it when the pump is on.

Use a low pressure pump and if all this is before the fuel filters, the pump can clog from debris. Some pumps have a screen filter for small micron particles but no real surface area for larger debris.

Pumps are good ideas.

scenarioL113 · Post by **scenarioL113** » Mar 15th, '10, 16:31

In Memory Walter K · Post by **In Memory Walter K** » Mar 15th, '10, 17:19

Seems like a lot of shut-offs, no?

Bruce · Post by **Bruce** » Mar 15th, '10, 17:39

Yes thats correct on the valve placement.

I've had good luck with Walbro pumps.

Walter, Unless your going to run the fuel thru the fuel pump, thats about the way to do it with one pump feeding both engines from either feed.

scenarioL113 · Post by **scenarioL113** » Mar 15th, '10, 19:11

Yes it is a whole bunch of shutoffs. I was hoping someone would chime in and tell me the easy way to do it.

LOL!

Bruce · Post by **Bruce** » Mar 16th, '10, 07:21

The easy way is put the fuel pump in line with the engine fuel feed after the filter.

One pump for each side would require no valves at all.

scenarioL113 · Post by **scenarioL113** » Mar 16th, '10, 16:27

Will fuel flow without a problem through the pump when the pump is not in use?

I am using this pump:

http://performanceparts.com/part.php?partID=414573

Bruce · Post by **Bruce** » Mar 16th, '10, 20:23

The product literature on the makers web site does not recommend that pump for marine use. Most likely because its not UL approved.

scenarioL113 · Post by **scenarioL113** » Mar 16th, '10, 22:33

If I do install a primer pump I will use it. I did see the recommendation on there website and I dont see any reason why it would be a problem.

I am sure the recommendation is because they will not warranty it in the marine environment, since many people will not solder and heat shrink connections etc....etc.....etc....

If we were talking about a gasoline application then I would be more hesitant.

So what about inline, will these type of pumps allow product to free flow thru when not operating allowing it to be connected inline???

Bruce · Post by **Bruce** » Mar 17th, '10, 07:41

Yes many of that design will, but you should contact the manufacturer to be sure and also ask what the free flow rate is and what your engines need for GPH flow. There was no technical info on the manufacturers web site.

If you have Cummins engines, I would not recomend that pump as an inline pump.

If your going to use two pumps anyway and get away from the free flow issue, it would only take 1 valve.

On your main fuel feed line create a loop off it with two t's for the pump.

Then in the main line between the loop ends put the shut off valve.

Close when using the pump so it doesn't just recirculate.

Rawleigh · Post by **Rawleigh** » Mar 17th, '10, 12:43

How about a pump for each engine with two Tee valves on each one? Just bypass out to the pump and back into the line.

Tony Meola · Post by **Tony Meola** » Mar 17th, '10, 19:13

Doesn't Racor now make an electric priming pump that you put right on the Filters.? Not sure how expensive it is but that seems like less work and plumbing.

CaptPatrick · Post by **CaptPatrick** » Mar 17th, '10, 20:10

Not sure how expensive it

About $400 a pop for the 12v model... And only for the 900 & 1000 Racors.

http://www.foreandaftmarine.com/62-RKP1912.htm

scenarioL113 · Post by **scenarioL113** » Mar 18th, '10, 12:36

How about this:

The two fittings off the main pickup tubes (the outside ones) have fittings that have check valves in them before the shutoffs. I could probably run it like this and not have to ever turn any valves.

I can shut the valves if I had to though. I dont see any snags and fuel for the pump comes from its own separate pickup tube assembly and fuel will not travel thru the pump unless the pump is running. I dont have to worry about the pump getting clogged and messing up my fuel system.

What do we think about this setup???

Bruce · Post by **Bruce** » Mar 18th, '10, 16:29

Check valves?

Unless your carbureted gas, those things don't belong.

You will put undue suction on the engine primary pumps and cause premature failure. Also you can aerate the fuel and cause bubbles with check valves due to the increased suction.

Your last pic will work but I'd add a shut off in the crossover when running normal.

scenarioL113 · Post by **scenarioL113** » Mar 18th, '10, 17:42

The tank came with stainless check valves, thanks for the heads-up I will remove them.

I am in the experimental mode here and will add the shut-off.

scenarioL113 · Post by **scenarioL113** » Mar 19th, '10, 07:29

scenarioL113 · Post by **scenarioL113** » Mar 19th, '10, 07:38

I amended my plan and it is shown in the previous post. This should work without all the redundant shutoffs like I was thinking early on. With the shutoff at the pumps pickup tube it will not allow the engines to draw fuel through the pump when not in use.

When the priming pump is used the valve will get opened and both systems will get primed, which is OK.

If for some reason a need arises that I can only have one side (port or starboard) being primed then I can shut either side down respectively at the racor filters. I have already installed shutoff valves on the input and output sides of them.

Since this system is only to be used manually I guess it would be stupid to install the on/off switch at the bridge. I will either install the switch at the filters (in engine compartment) or at the pump which is at rear of the tank near rudder arm.

I hope this thread has been informative to those who may to do something similar.

Frank

bertram31.com

small 12v diesel pump for priming?

small 12v diesel pump for priming?

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