Fuel problem

[ghebbns]

Hi all,
I posted yesterday about needing a new fuel pump - unfortunately that was not the problem.  The new pump had the same issues. 
My fuel line goes from the tank to the primary filter to the pump to the engine.  I disconnected the outflow from the pump and turned it on - nothing.  So the pump isn't getting fuel.  The strange thing is that the primary filter seems to get getting fuel.  I had emptied the bowl and when I turned on the pump, I could see it fill. I had just put a new line from the filter to the pump, so that can't be the issue.  The filter is brand new as well.

My only thought is that there is an obstruction in the fuel tank that allows some fuel through, but not enough for the pump.  Any other suggestions?

Thanks,

Greg

[lazybone]

Try disconnecting the supply line from the tank and blow into it to see if it's clogged.
It's obviously not a permanent solution but it might tell if that's the problem.

[Jon W]

Stu Jackson had a fuel starvation problem he traced to a ball check valve in the Racor housing where the fuel enters. I believe his post on the subject is listed in the 101 Topics. Maybe your problem is the check valve.

[rjabara]

Greg, I just went through a beginning to end investigation (also incorrectly assumed fuel pump) of my fuel starvation problem.  You can follow that just a few lines down from your posting called something like "fuel pump fail".  For mine, it was gunk in the line at the secondary filter (i think).  Anyway, I started at the tank and removed the pickup to make sure it was not clogged, then to Racor (replaced and checked in and out), then pulled the line connected to the secondary fuel filter and ran the pump and it spit out the culprit into a bucket with a few cups of diesel.  Changed the secondary filter.  Took a few tries to start after that but then started right up.  My guess would be either in the tank at pickup or a blockage at the secondary. 

[KWKloeber]

Hi all,
I posted yesterday about needing a new fuel pump - unfortunately that was not the problem.  The new pump had the same issues. 
My fuel line goes from the tank to the primary filter to the pump to the engine.  I disconnected the outflow from the pump and turned it on - nothing.  So the pump isn't getting fuel.  The strange thing is that the primary filter seems to get getting fuel.  I had emptied the bowl and when I turned on the pump, I could see it fill. I had just put a new line from the filter to the pump, so that can't be the issue.  The filter is brand new as well.

My only thought is that there is an obstruction in the fuel tank that allows some fuel through, but not enough for the pump.  Any other suggestions?

Thanks,

Greg

I will say it once more for about the 100th time. 

Mates and matettes, Do NOT start replacing parts willy-nilly.

troubleshoot, Troubleshoot, TROUBLESHOOT to eliminate as much as possible.   Then start replacing parts willy-nilly.

Generally the procedure would be:

Look at Stu's write-up about the check valve. 
Check the filter on the Facit pump.
Verify it will pump from a fuel jug.
Bypass the primary filter to see if the Facir will pull directly from the tank.
Those will help to eliminate "non-causes."

[Jon W]

and verify the filter is removed from inside the fuel tank, the valve on the tank is all the way open and not clogged, and the hose from that valve to the Racor is not clogged.

[KWKloeber]

Jon
I understand what you are saying are possible causes, but that's my point.  Do not invest unnecessary time/effort to pull the fuel suction from the tank unless the Facit won't pull using a new hose directly on the tank. That procedure (my #4) eliminates everything except a tank/suction screen blockage.

Being able to more easily troubleshoot pump/blockage/air leak issues is a PRIME reason to re-plumb the fuel bleed knob in m-25s/XPs. But nobody listens!


Aside: years ago a bud had closed the fuel cock, forgot about it, and next time aboard started up in his slip. 
He slipped into gear and she stalled. 
Cranking he couldn't start it, and someone went below, checked and opened the fuel cock — she started right up — in gear — and he smashed the bow of his C&C into the the wharf.

and verify the filter is removed from inside the fuel tank, the valve on the tank is all the way open and not clogged, and the hose from that valve to the Racor is not clogged.

[Jon W]

The filter in the tank should be removed per the Critical Upgrades list.

Do you have a diagram on how you think the fuel bleed knob should be re-plumbed?

[ghebbns]

Thanks all for the helpful suggestions.  I was 99% sure it was going to be the ball valve in the filter housing - but no luck.  Clean as a whistle.

I believe I have narrowed it down to the pickup tube in the tank.  I have read as much as I can about how to pull this, but concerned that I read some things about the tube falling off into the tank.  Before I take this out, any tips or suggestions?

Greg

[ghebbns]

And the mystery continues ...
Removed the fuel pickup tube and it is clear (no filter).

When I tried to pump fuel from a bottle directly into the pump inlet, no good.  But if I remove the outlet hose from the pump, it pumped fine.

Going to verify tomorrow that none of the hoses are clogged.  After that, I am out of ideas (time to call an expert!!)

[Jon W]

Checking the hoses for clogs is what I'd do. Did you try disconnecting the outlet hose at the engine end to see if it pumped fine?

[KWKloeber]

Do you have a diagram on how you think the fuel bleed knob should be re-plumbed?

Jon
The m-25 bleed was originally just a hollow hex bolt that was loosened to bleed fuel.  I catch it in a solo cup (with the bright white interior its easy to check for gunk.)

I replaced thd bolt with the knob and made no other Mod.  So I simply catch bled fuel from the hose barb into a cup.

The XP has the bled fuel going to Injector #1. I understand Kubota's reasoning but for our purposes it's better to see what's being bled vs the ease of not needing to catch it in a cup.  It's better (IMO) to see the bled fuel, look at its condition, verify that the flow is strong, and there is no air sputtering, and if there is, when it stops.  You can't tell any of that how Kubota plumbed the knob.

Plus, it's easier that way to troubleshoot if there is a suspected pump issue.


So all that's needed is to remove the hose from the knob's barb and plug it off.
If one wanted to still be able to send bled fuel to the tank, leave the hose connected and put a 3-way valve inline.

[KWKloeber]

When you say "outlet hose", where were you attempting to pump to?   Another bottle, or thru the secondary filtet?  Or....?

When I tried to pump fuel from a bottle directly into the pump inlet, no good.  But if I remove the outlet hose from the pump, it pumped fine.

[ghebbns]

Thanks all for the help.  I am making progress.  With the electric pump engaged, I am now getting fuel flow to the secondary filter.  I know I have to bleed the air at this point, but not 100% clear on the best way to do that. 
I see mention of the bleed valve on the secondary filter.  The filter location makes it hard to see so not exactly sure where that is.  I also see mention about a knurled knob - is this the same thing?
If anyone has photos of where best to bleed, that would be incredibly helpful.

Greg

[KWKloeber]

Greg

Where/what was the blockage?

Follow the fuel hose from the Secondary Filter up to the Injection Pump.  If you have an XP here **should** be a knob on the side of the Injection Pump, near the top.

It would be better for YOU to post a picture of what YOUR engine has so that we can guide you.

The bleed on the Secondary Filter housing is simply a machine screw that you open. You're better initially bleeding at the Injection Pump to see if she starts. Then go deeper if necessary.

Ken

Thanks all for the help.  I am making progress.  With the electric pump engaged, I am now getting fuel flow to the secondary filter.  I know I have to bleed the air at this point, but not 100% clear on the best way to do that. 
I see mention of the bleed valve on the secondary filter.  The filter location makes it hard to see so not exactly sure where that is.  I also see mention about a knurled knob - is this the same thing?
If anyone has photos of where best to bleed, that would be incredibly helpful.

Greg