CAT 3126 Fuel Prime Pump Replacing

[david_h]

I am wondering if anyone has changed one of these before?

I am replacing one of the fuel priming pumps on my boat. Lucky it is on the 'easy' side of the engine compartment.

I believe that if I remove the fuel filter and small metal pipe that runs between the priming pump and the fuel filter, that I should be able to get a wrench on the priming pump body.

Here is a snip of one end of the small metal pipe that I am referring to. It starts at the fresh water hose, (before the impeller pump), and ends up at what looks to be a fuel fitting. I just want to confirm that this pipe contains water and not diesel.

Also, here is a snip of the parts drawing. Can anyone advise if part '2' is part of the hand pump or part of the 90-degree valve?

Many thanks,

Dave

 

[dtfeld]

Yup. Easy Job. There is a part number, that is only the pump, not the asembly. I think $70. I beleive that is a fuel line you are looking at, and will not need to be removed if the pump is all you are after.

http://clubsearay.com/index.php?threads/3126-priming-pump.96637/

 

[dtfeld]

This might be what your looking for?? Its a hard pipe fuel line...so it contains fuel.

 

[david_h]

Hey I replaced the pump, but still no go on the priming front. You were right, it was pretty simple.

The part '4' above, is not the pipe that I was referring to in my initial post. It starts around position 1-2, but ends up connecting to the raw water hose, (I am thinking fuel cooler maybe?).

I also popped the bolt out that is located on top of the fuel filter assembly. I can see the top of the fuel filter and then down into the filter a bit, and it is dry after pumping for a few minutes.

So I am a bit confused here. The fuel filter was only about 1/2 full, when I pulled it off, to replace the priming pump.

Any other ideas what could be the cause, or other things to try?
air lock someplace?
I can see where somebody previously, has worked on the nut highlighted below with the red arrow:

Although not ideal, what are the ramifications of starting the engine without doing a prime?

Any help certainly appreciated.

tks

Dave

 

[fwebster]

Simple.......if the engine has air in the fuel system and needs priming, you aren't going to get it to start very easily without priming the system. You may crank on it for 45 minutes or an hourbefore you push all the air out of the fuel lines, gallery, and injectors.

If you get a 3116 or a 3126 air bound, purging the air out with t he starter is very hard on the starter ring gear, starter gear and bendix. Just makes no sense to wear those parts, which are expensive and labor intensive to replace, unnecessarily.

 

[david_h]

Hey Frank, thanks for responding. Can you advise how to prime the system, if the priming pump isn't doing the job? How can you get the air out?

tks

Dave

 

[fwebster]

If the system is full of air, check your fuel manifold or valves and be sure that the system is returning fuel to to the same tank it is drawing from. Then, open the Racors and fill them to the brim with fresh, clean diesel that you got from a pump with a filter on the nozzle. Next, remove the Cat secondary filters and fill them to the brim just as you did with the Racors and reinstall them.....and wipe up the fuel you spilled. Next, go to the helm and advance one throttle about 1/2 way, press and hold the emergency srtart switch, then and press the starter switch and hold it down for no longer than 30 seconds. If you are lucky, the engine will fire on one or more cylinders. If it does, advance the throttle until the engine begins to smooth out. As it smooths out, retard the throttle setting to keep the idle speed at about 1000-1500 rpm, then continue retarding the throttle to the idle stop as the engine smooths out.

If the engine doesn't start after trying to start it 30 seconds, release the start switch and re-fill all the filters and repeat the start procedure above.

Priming the system this way fills every component with fuel up to the outlet on the Cat secondry filter. The only part you cannot manually prime this way is the fuel line going from the Cat filter to the fuel gallery in the cylinder head. If the system is completely full of air, you may have to repeat manually filling the filters.

It is very hard on the starter ring gear, bendix, starter gear but you can prime the system by grinding away on the starter after filling the filters by hand. If you try this, expect the process to take a while because you only need to run the starter for 15 seconds at a time. After 15 seconds, you need to let the stater cool down.

Purging the air is a simple process but it takes a little while so be patient. Good luck with it.........


Frank

 

[david_h]

Thanks Frank for the detailed response.

I completed most of the steps noted with success! It took 4 taps (each attempt the starter turned less than 1 second), of the starter to come to a smooth idle, and I let it run for about 10 minutes to be sure that I had good fuel flow.

Thanks again!

Dave

 

[mrsrobinson]

I am trying to figure out what this part does, Google is not being nice to me. It sounds simple enough, priming. I assume when I turn the key on this does something to prime the fuel?

 

[mrsrobinson]

I figured it out, it's for Manual priming. You're not supposed to fill a diesel fuel filter up with fuel when replacing even though a lot of people do