Racor vacuum indicator

[tlkenyon]

2015 R25sc w/ D3-150 @ 1,153 hours. Racor vacuum indicator (the piston kind, not the circular gauge) was showing high vacuum (in the red), indicating a fouled filter. Took the filter out and it looked totally OK. There was no water in the bowl. Put a new filter in and the indicator was again in the red. Replaced filter again, same result, so I know it's not a fouled filter, but there is a restriction somewhere. Traced fuel lines, no kinks. Last year, removed screen and the end of the pickup tube, and ran 50+ hours after that with no "in the red" indications. Got any ideas?

 

[Rocky]

You removed the screen the Pick up tube? Was it clogged? IF it was clogged last year, I would think the same issue could clog - or restrict- an open tube. I would look there again.
Biological issues can develop in a diesel tank and plug screens and filters.

Other than that - or a faulty vacuum gauge- I have no other suggestions.

Does the engine seem to run ok?

Rocky

 

[tlkenyon]

Pickup tube was not clogged. Removed the screen as a preventative measure as recommended on this forum. Just took racor off, disassembled, reassembled. No cleaning was necessary. Started motor and max vacuum was on the gauge. Cleared gauge and restarted to same result. Tomorrow gonna disassemble fuel system from racor to tank. Might just install new fuel line. Might also get a new gauge. Boat is on the hard, so no real way to see if it runs OK under load. Thanks for the response.

TK

 

[knotflying]

For the hell of it. I would make up a temporary auxiliary tank and connect it to the filter assembly and see what reading you get. Or - Stranger things have happened, if not too expensive maybe the gauge has gone bad and buying a replacement to see if there is a difference would be easier.

 

[tlkenyon]

I might just do the aux tank thing. It would be easy to do. Thanks for the tip.

Yesterday, I removed the pickup tube and blew the line clear from the end of the pickup to the filter housing. (I had for gotten how bad diesel tastes). Nothing came out of the line. With a piece of tubing, sucked a fuel sample from the bottom of the tank thru the pickup entry point - clean fuel with no sludge or water. Upon reassembly, priming and startup, the gauge showed at the end of the green (near the yellow), not in the red as previous. Cleared gauge and restarted several time to same result. So, there is some improvement. Gonna put the boat in the water and run a few hours under load (greater fuel flow) and see what happens. Also ordered new gauge. Note that the current gauge has fuel in it - don't remember if that is normal or a sign of malfunction or not.

 

[tlkenyon]

Put the boat in the water and ran it under load - WFO. The vacuum gauge went into the red. It was a new filter cartridge. Drained filter housing, no water or sediment. Got home and ran the engine for just a few seconds with the filter cartridge removed. Vacuum gauge immediately went almost to the red. Concluded that there is a kink or delamination in the fuel hose. Ordered new fuel hose; 10 feet of SAE J1527 Type A1-15 3/8" ID. Crossed fingers....

 

[tlkenyon]

I found the problem!!

In the process of getting situated to replace the fuel hose, I removed the drop tube. On the bench, I removed the 1/4 x 3/8 brass bushing from the drop tube. There was a piece of "stuff" hidden in the 90-degree bend right at the top of the drop tube. I appears to be fragments of something like a plastic bag. It is not large, but just large enough to partially plug the fitting and stiff enough to lodge in the 90-degree bend. I coaxed it out with a tweezers. Reassembled everything (without replacing the hose). Engine runs with no deflection of the vacuum gauge. Will post a photo someday.

Amazing how such a small piece of schmutz can cause such a problem. Moral of the story - take everything apart down to its components and inspect everything. Make no assumptions.

 

[Hydraulicjump]

Congrats! You have reinforced something we all should pay attention to. When stumped, take it apart with the intention of reassembling it. Along the way, you may 1) find the problem and/or 2) solve the problem in some mysterious way that you cannot exactly explain. Regardless, you learn a ton. I bet Brian has pulled a lot of stuff apart just to see if he can put it back together and figure out how it works (I had this experience with a windlass recently). This is the Baby Boomer's version of ctrl-alt-delete or just pulling the plug out of the socket.

Glad to hear this worked out.

Jeff