How does this setup work

harleyman_1000 · November 08, 2014, 02:21:05 PM

Which is the out side

harleyman_1000 · November 08, 2014, 02:23:10 PM

Can't get picture to upload?

harleyman_1000 · November 08, 2014, 03:12:03 PM

Here is my fuel setup. There are 2 filters and the prime pump in the picture. My question is, is one of these filters for incoming from the tank and the other for outgoing to the engine? My bus won't start. After I removed the fuel line going from the prime pump to the filter on the right, and hit the prime switch it pumped a small amount of fuel out and then nothing more. I then tried to start it and it started for a second and then nothing again? Any ideas?

sparkplug188 · November 08, 2014, 04:01:16 PM

I have always had success using a vacuum pump on the schrader valve mounted on my secondary fuel filter base. Fuel gets sucked from the tank, through the primary filter, through the fuel pump, and into the secondary filter. Sorry, I don't know how your priming pump works $:-\$ hopefully others will chime in.

luvrbus · November 08, 2014, 04:32:47 PM

What does the other line on the pump tie too the fuel pump? I can see the line on the primary filter

harleyman_1000 · November 08, 2014, 05:20:44 PM

Not exactly what your asking Clifford? If you mean where do the 2 lines coming off the prime pump go, then the answer is, 1 line goes to 1 filter, and the other line goes to the other filter.

chessie4905 · November 08, 2014, 06:04:08 PM

The fuel pump on the engine sucks fuel from tank through the primary filter to engine pump inlet and it then pushes the fuel from pump outlet through the secondary filter to the fitting on the cylinder head which supplies fuel to the injectors. The excess fuel leaves heads through restriction orifice and then back to tank. I would unhook the fuel prime pump lines and put the suction of it in a container of clean fuel to make sure it isn't plugged up. I would think the priming pump would be between primary and tank. If it flows fine after the test, maybe it is pulling fuel from one of the filters which is somewhat plugged, or the line from the tank has issues. Most of the time it turns out to be plugged filter/s. The shop manual for the coach engine or DDA manual indicate tests to determine proper operation of engine fuel pump if diagnosis points to it being the issue.

lvmci · November 08, 2014, 06:13:48 PM

Hi Scott, did you fill both fuel filters up to top with diesel before screwing them in, sorry if you already knew to do this, lvmci...

gumpy · November 08, 2014, 06:30:02 PM

So, if I understand, your priming pump is sucking fuel from the tank through the primary filter and squirting it into the secondary filter output line?

That's not going to work. It leaves the line from the primary filter to the engine fuel pump and back to the secondary filter lacking in fuel, and priming
the fuel pump is really the whole reason for having a priming pump in the first place. If that engine pump has no fuel in it, it's not going to suck fuel from the filter.

That priming pump need to suck fuel from the tank and push it through the primary filter and on to the pump and secondary filter.

Now, maybe I'm not understanding your setup, and the photo is not really very clear on what's what.

It sounds to me like you either have a plugged primary filter, your pickup tube is plugged, or quite possibly, your engine pump is just airlocked.
Suggest you change the filters, and blow air from the primary filter back into the tank and then reprime (might want to determine if that priming
setup is really correct, though).

gumpy · November 08, 2014, 06:42:07 PM

By the way, it would really be helpful if you could give a detailed description of that photo and the filter setup. Which line comes from the fuel tank, and which filter does it go into (draw some arrows
on the photo if necessary). Do the same for all the lines and both filters. I'm assuming that green thing in the photo is your priming pump?

brmax · November 08, 2014, 06:43:37 PM

Scott the norm is the right side of the pump as we are looking at it in this pic and also your signature pic, for the outlet.
I guess the left filter would be my first change out.

edit Is that a Schrader valve on a steel line at the right filter, I got my cheaters on.
just noticed that?

harleyman_1000 · November 08, 2014, 08:03:23 PM

Not sure about the Schrader valve(not sure what it is or looks like)? I will look in the morning to see, and I will take better pictures. This is the setup that was on the bus when I bought it and it ran fine. I have never removed the fuel filters, so they should be full of fuel. The line from the tank goes to the filter on the right. The bus was running fine, and I idled it up and it started running rough and when I let it idle normally it also ran rough? I then shut it off, and when I tried to start it a couple days later it wouldn't start, and this is where I am today. I'm wondering if I might be out of fuel? The gage reads a quarter tank, but the bus is slightly sloped down forward.

Ed Hackenbruch · November 08, 2014, 08:32:21 PM

Put more fuel (at least 20 gallons) in your tank and try it again.

gumpy · November 09, 2014, 12:38:00 PM

First thing is don't trust the gauge unless you've verified its accuracy. I once had 1/8 of a tank. Took me and another busnut friend a full day to get it reprimed
and running again.

Use a wooden dowel to stick the tank. It's possible your fuel pickup isn't on the bottom. They've been known to crack partway up, which basically means they only suck
fuel to the level of the crack. It's also possible with the slope you describe that the fuel in now on the wrong side of the tank. Since you are questioning it, I suggest
you add 20 gallons and see what happens.