25XP Fuel Priming Conundrum

jibes138 · Feb 7, 2015

captnron said:
Guys, Here’s a conundrum I came across that hopefully, someone has dealt with this & found a solution. My pal has a very nice 1988 Newport 30. Last week, we replaced the exhaust piping. There was a guillotine break in the threaded C.S. piping at the mixing elbow. We replaced this with an exact duplicate & went to start the engine that had run fine to this point. He of course, had exhaust water spraying in his engine compartment for about 20 minutes unknowingly. When back at the dock, he cleaned this mess up & we replaced the exhaust piping the following Saturday. We hit the fuel pump on but, the engine that had always started, would not start. Today, we went down to change the old suspect fuel pump. We tried to prime the system to no avail. He has a 25XP with the de-compression lever & a master bleed valve before the injectors. Herein lies the mystery & the weird filtering design. The engine is in the quarter berth, with limited access to the secondary filter & the fuel pump. The PO removed the fuel pump to a different location for access. However, he used a 2 micron filter as the primary & from there to the pump & then to the 10 micron secondary filter after the pump WTF? When opening the main bleed valve to prime the fuel to the injectors, no air hissing nor any fuel came out. We checked the discharge off the pump & fuel flowed freely. We changed the secondary filter out & when venting, got a steady flow of fuel yet from here to the bleed valve for air/fuel venting, nothing. We also cracked the three lines to the injectors & still nothing. No air spitting & no fuel flow. Aside of the Mickey Mouse filtration system setup, we replaced/eliminated the tank-to-2 micron primary filter-to-pump-to secondary 10 micron filter but, the injector manifold showed no air or fuel flowing to this point or the bleed valve. Has anyone had a similar problem with this style engine & found what caused this & possibly found the fix? The fuel shutoff valve was open & the de-compression lever was in the correct position. As I said, a CONUNDRUM! CR

i have a similar engine, the M25. The Set up of filter pump filter is correct but a 10 micron or higher is recommended for the primary. It sounds like a fuel line is clogged. Fuel lines should be replaced at ten years. Maybe a chunk of rubber came off the ID and caused a clog? Fuel should return to the tank so start there and work backwards to find the blockage if any.

Ron20324 · Feb 7, 2015

get rid of the 2 micro.

waternwaves · Feb 7, 2015

" Fuel lines should be replaced at ten years..."

You are referring to the flexible fuel lines???? not the steel tubing?

jibes138 · Feb 8, 2015

waternwaves said:
" Fuel lines should be replaced at ten years..." You are referring to the flexible fuel lines???? not the steel tubing?

yes. The flexible lines deteriorate over time get brittle and can crack. I learned it the hard way :>) so I am talking from real world experience. Better to replace the before they fail then to have a failure at a bad time.

jibes138 · Feb 8, 2015

captnron said:
Jibes, That's what I was thinking, a clog in the hose or tube/fittings. The only short-run orig. hose is to the fuel manifold/bleeder. It was late in the day so, we didn't get to disconnect any fittings or change that one hose out. But, the mystery is that the engine ran fine until adding the exhaust piping & just suddenly not start immediately after. Nothing in the fuel system was touched. I did notice that the decompression lever seemed frozen. We got it looser but, the only way to check this is by removing the valve cover. My pal was pretty bummed out by then. CR

a diesel has the fuel circulate back to the tank. You should have flow with the motor off and just the pump running. Since you described a no flow condition it seems like a problem. If the 25xp is like the M25 there is a knurled bleed screw near the front of the engine, you open it for a while to get the air out. See if it has one of those.

Capt jgw · Feb 8, 2015

The exhaust work and no-start must be coincidental. I wonder if the bleed valve screw actually broke when you opened it, and it's not really open? Or is it just clogged? I would take that last hose to the bleed valve off then run the pump. If you have flow to the valve but none out, it must be the valve. The hose from the secondary filter to the bleed valve and injection pump should be the first one to get replaced. It's after the filters, so if it starts shedding rubber inside it will plug up the injection pump, which is what those filters are there to prevent.

Maine Sail · Feb 8, 2015

captnron said:
Capt,

I agree with your theory pal. I wanted to remove the bleed valve but, it was late in the day. But, even if this is clogged, venting the injectors & manifold fittings, no fuel at all. It's just strange that what worked one minute stopped working the next.

CR

Jump the fuel pump direct to 12V and check at all points you can crack.... Are you sure there is no valve on the retun line...? Don't forget the fuel pumps have an internal screen too. You can Aldo crack the bypass screw do she self bleeds...

jibes138 · Feb 8, 2015

captnron said:
Capt, I agree with your theory pal. I wanted to remove the bleed valve but, it was late in the day. But, even if this is clogged, venting the injectors & manifold fittings, no fuel at all. It's just strange that what worked one minute stopped working the next. CR

the bleed screw on the engine doesn't vent air or spit fuel out directly. It increases the fuel flow rate so the air gets flushed out of the lines back to the tank. If you have flow in front of the bleeder and no flow after the bleeder it is very likely the bleeder is a problem. I've never had one apart so I can't comment further.

Maine Sail · Feb 8, 2015

You are sure you did not bump the kill cable, any wires etc. during the repair. It would be quite a coincidence for it not to run the same after changing the exhaust elbow...

Maine Sail · Feb 8, 2015

captnron said:
Main,

I checked everything pal. aside of the stiffness of the decompression lever, nothing was closed off. The only things to check are from the secondary thru to the injectors.

I assumed the bleed valve as on my 3M20a, worked the same but Jibes says no. I know when I bleed my valve, I get hissing air then wet spitting then fuel, system is primed.

This is just bizarre man.

CR

On some of the later Universals the bleed screw is a bypass return screw not a typical messy bleed screw. It opens and bypasses fuel back to the tank. Put an ear on the tank and listen for returning fuel...

Windborne · Feb 8, 2015

I'm the pal with the Newport 30. Thanks for replies. A little history. Over the past 4 years that I've owned the boat I've had minor off and on again trouble starting the engine that generally pointed to fuel flow. I have steadfastly changed primary and secondary fuel filters and the pump filter. Just recently replaced the fuel pump and hoses from primary to pump and pump to secondary. Last summer had the tank/fuel cleaned with more interest in tank cleaning than "polishing" fuel. Plenty of sludge removed and Racor bowl stays clear. Fuel is making it from tank to secondary filter. When we loosened nuts to injectors fuel dribbled out though maybe just residual in the line.

Donnybrook · Feb 8, 2015

Disconnect the fuel line from the secondary filter at the injector pump. Put the line in a clean container and have your buddy turn the engine control switch on. You should get a steady flow with no foam. Let it pump at least a quart. That should give you clean twice filtered fuel that you can pour back into the tank. This test will show you which way to continue troubleshooting. You will not get any fuel from the injector lines unless the engine is turning over.

Maine Sail · Feb 8, 2015

Windborne said:
I'm the pal with the Newport 30. Thanks for replies. A little history. Over the past 4 years that I've owned the boat I've had minor off and on again trouble starting the engine that generally pointed to fuel flow. I have steadfastly changed primary and secondary fuel filters and the pump filter. Just recently replaced the fuel pump and hoses from primary to pump and pump to secondary. Last summer had the tank/fuel cleaned with more interest in tank cleaning than "polishing" fuel. Plenty of sludge removed and Racor bowl stays clear. Fuel is making it from tank to secondary filter. When we loosened nuts to injectors fuel dribbled out though maybe just residual in the line.

Well that explains it you guys did not bleed this engine correctly.... Use the bleed or bypass screw NOT cracking the injectors.....