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Old 02-26-2018, 01:47 PM   #21
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Any resolution?
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Old 03-23-2018, 07:03 AM   #22
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Any resolution?


As a newbie this is my biggest mistake thus far.....failing to close the fuel shut off valve and being unlucky as the fuel solenoid locked in an open position. Diesel fuel flooded the entire engine causing a hydrolocked situation.

tilitrider and kapnd suspected the problem as did Nizda. Nizda assumed that I would know to turn the valve off, however, no one ever told me this. Chalk this up to experience.

Anyways, the diesel and oil were removed and changed respectively, and I’m up and running again....some $3k poorer.

In the next month I plan on removing the injector pump and the injectors for cleaning and inspection.

I also plan on getting the engine up to temperature more often!
.......and shutting off the solenoid as well as closing the fuel shut off valve.

Thanks to all for your advice!

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Old 03-23-2018, 08:23 AM   #23
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Is the 555 unique in having this type of fuel leak problem? My curiosity is piqued as to how many of us shut off our fuel systems when leaving the vessel.
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Old 03-23-2018, 09:23 AM   #24
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Yes, I'm still really confused about what exactly happened to flood the engine. A stop solenoid that stays open would result in an engine that can't be shut down. But once stopped, fuel isn't going to flood past it. And I have never heard of a need to turn off a fuel supply when shut down to keep an engine from flooding.

I don't doubt it was flooded, but I don't understand the mechanism by which it happened.
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Old 03-23-2018, 10:12 AM   #25
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I don't like being correct in this case, since my engine is V-504 and both engines (504 and 555), so as V-903 share the operation manual with that caution. I think, as I have said earlier, that if that is the case, it is a design flaw.

I am curious if you have list of the costs with those 3k? Really curious if you had to disassemble the engine!?

Before you install the ball valve in front of electric shut off valve, mind that I do have that (manually controlled one) and it is PITA, I will use that only in emergency (i.e. fire hazard, but in my setup it is not installed in engine room) and I am not closing it anymore in common use. I will explain:

1. You will forget to open the valve more than once and of course, you will be aware of that when the engine stops due to lack of fuel (vacuum made is probably also bad for the fuel system components) and then you have to purge the air to start up the engine. Hopefully, the engine will shut down after you exit tight spaces between slips in port.

2. If you close the valve and remember to open it for the next use, but the boat was on the ramp in between while tilting angles, it can happen that you will have to purge the air again. Mind that I do not have any leak in fuel system and valves are new so I was confused where did the fuel go and how, but it did, and before leaving the ramp in water, I had to purge the air to start the engine. Awkward.

If you already decide to proceed with additional valve route, I highly recommend using electric valve with same control wires for shut-off valve, so you will not start with valve closed ever. They will open and close at the same time, but you will have that additional protection from such case. But, if you leave the key in ON position, it is the same situation as having just shut off valve.

Anyway, it seems to me that this flaw is easily prevented if it is not left for long time with opened shut off valve (manually or electrically) and those shut off valves seems to last a long time.

P.S. Beside manual ball valve I also have fuel bulb (with internal check valve) in line for easier air purging when needed, which I have not done for about two years, since I stopped closing manual ball valve (no problem even after the ramp).

I would like to hear some other smart (smart meaning simple) solutions for easy prevention of such potential problem.

I strongly advise you to find the "Marine diesel operation and maintenance manual" from Cummins for 504/555/903/855/1710 (here is the link to see how does it look like

https://www.ebay.ca/itm/Cummins-504-...9aq9bt&vxp=mtr

, but I am sure you can find it from someone in neighborhood with those engines. It it is very valuable, not only for these engines, but for marine diesels in general, because with specific instructions, very detailed explanations are given why to do so, so kind of it can be used as a general learning book about marine diesels (older engines though, but most principles are the same today). Too bad that manuals for new engines are not so detailed considering that we are in "computer era".
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Old 03-24-2018, 01:00 AM   #26
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Glad you found out what the problem was. I'm sorry you got caught with this. Never considered the shutdown valve as a source. Learned something.

I did have a situation about 8 years ago where the engine would not shut down but a few seals and it is back to normal.

I wonder if that was the initial cause, your valve needed new seals. They were not bad enough to do as mine did, simply refuse to quit, but bad enough to leak fuel.
I suspect also that your tanks and the fuel level must have been above the engine and the valve.

I do shut off my tank outlets unless I am travelling day after day. But in home port those valves are shut.
Maybe I'm just lucky.

Better boating to you.
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Old 03-24-2018, 07:27 AM   #27
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"My curiosity is piqued as to how many of us shut off our fuel systems when leaving the vessel."

Very few, although deck operated tank shut off valves are required for USCG on many commercial vessels.

A simple pull handle , a hunk of outboard shift cable and a FUEL, not a water valve for each tank is needed.

Insurance that is easy to afford ,
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Old 03-24-2018, 01:27 PM   #28
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CUMMINS 555’s

I'm still struggling to understand how this led to a flooded engine. Even with no shut off, and with the stop solenoid in the run position, fuel would have to leak past the injection pump, and through the injection nozzles that only open at multiple hundreds PSI. It only seems possible if there were also massive bypass leakage in the injection pump AND the injection nozzles.
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Old 03-24-2018, 02:40 PM   #29
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As explained in post #7, the 555 uses camshaft operated injectors like the 2-stroke Detroits. Each injector is a mini-pump. No injection pump. If the injector for the cylinder(s) in question was up on a lobe, it's open. That said, I would think the fuel tank level would have to be above the engine injectors...but hard to say without a full picture of the fuel system configuration.
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Old 03-24-2018, 02:46 PM   #30
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PT System leakage.
There is a difference between the old PT systems used on the 504,555,903 and several other Cummins engines of the day and newer injection systems.

The PT pump is not the typical injection pump seen on many engines and newer Cummins, Deeres, etc. The pump does NOT meter the fuel directly to the injector except by varying, relatively low pressure fed by a common tube and then a gallery in the head. The injectors actually meter the fuel.

The injectors are operated from the camshaft by rocker arms and that is what feeds and closes the fuel off to the cylinder. It's the varying pressure fed by the PT pump that determines how much fuel the injector actually feeds the cylinder.

In newer systems that close off is done by the injector pump for the individual pistons.

Since I'm not an expert I too wondered about it but I'm guessing that if the tank fuel level is above the PT pump then leakage could occur if the shutoff solenoid fails to close 100%. It would only take one injector to cause trouble if it hung up combined with a slightly goofy shut off valve.

My example was that my engine would not shut off untill the valve was re/re'd. If my engine had been down a while, the fuel had been above the engine combined with a flakey valve then maybe I could have a similar problem.


All that said the shutoff valve is mounted on the side of the PT pump, between the heads at the back of the engine. It can be removed and resealed without removing the PT pump. You might get the throttle shaft seal replaced if you go ahead with PT pump removal. That may well be a good move. At least the PT does NOT have to be timed.


Did you have any sign of shutoff problems like mine where the engine continued to run on after supposedly shutting the engine off? Mine did slow somewhat but still ran. Shut 'er down one day properly and the next it wouldn't.

Is it possible the fuel level in the tank is above the engine PT pump?

As for shutting off the fuel at the tanks that would be a good fix. Yes, you will goof once in a while but even that could be kept to a dull roar by a tag over the starting switch and controls. Better than flooding the engine.

I will comment about an explanation from Paul Foulston who was a frequent contributor on Boat diesel and was a real expert on these engines. The engines do need to be run at a good load to keep the injectors clean. He said they are what is called an open injector unlike most injectors with a high pressure feed directly from the pump. They can get packed with carbon he said if not run with a decent load. Don’t need to abuse it just ensure it gets fully up to temp and run with a good load.

My last comment came as I was typing this. Tank venting allowing a pressure buildup in the tank and thus the fuel delivery system. If the vent to the atmosphere is obstructed maybe pressure built up after shutdown. These engines feed a LOT of fuel back to the tank by the return line. That fuel can be very warm, almost hot, and combined with the tank picking up more heat after shutdown from a hot engine maybe that contributed. Take a good look at the tank vent line that it is not plugged, collapsing, kinked or obstructed in some manner. If that happens maybe the pressure build up forced the fuel through. If this is the case it may not need a fuel level above the engine, just a poor vent hose.
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Old 03-24-2018, 03:04 PM   #31
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While this injector style may be old , Detroit used it in 1936 and up it may be making a comeback.

Small comercials of the world are not in love with $1,000 injectors or a boat that stops for a bad transistor.

These injectors can be sized to the specific boats operational use and may with DEF finally allow modest sized engines to make the air police Tier 10m ,Tier 20, whatever, happy.''Fingers crossed , imagine repairable engines again!
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Old 03-24-2018, 06:47 PM   #32
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I get the whole unit injector design, but reiterate I am a total amateur with the specific designs and variations. I have looked pretty closely at Scania's current unit injector design since I'll be using it, but that's the only one.

I thought that all injector "tips" have pressure activated valves at the end. That's what ensures a build up of pressure before they spray, and enough pressure to get a good spray pattern. The pressurized fuel may come from the plunger in a unit injector, from a high pressure common rail pump, or from a conventional injection pump. But in all cases, you need to hit the injector nozzle with high pressure for it to open. When injectors are tested, the pressure at which they open is tested, as well as the resulting spray patten. So given this, I would have thought that pressurized fuel would be required to push any past an injector nozzle, regardless of the injection system type. I didn't think there was ever a case of any sort of open valve that could result in fuel flow unless the fuel was also pressurized to injection pressure, which is way higher than he head pressure of any fuel tank

Is this not the case? Again, I'm no expert. But maybe one of our diesel gurus can help out here?
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Old 03-24-2018, 06:56 PM   #33
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I don't know about a comeback but it was a good system. Maybe it can be adapted with electronic controls. Will be past my time.

I was thinking about the flooding some more and thought of another way to flood the engine.

Not through the pressure fuel line but rather by the fuel return line.

It would take a few things to be present in the boat and the tank plumbing:
--a goofy tank atmospheric vent as mentioned.
--a return line dip tube that goes below the fuel level. Many boats are plumbed so the return line goes to a dip tube that nears the tank bottom to avoid aeration of the fuel. These engines return a lot of fuel so aeration could be a problem.
--a failed return line check valve. There is one on the R.H. cylinder head at the back of the engine. It's about 1.25" diam and 3" long. Intended to hold fuel in the heads so the fuel does not drain back to the tank which can cause hard starting requiring lots of cranking. It does show in a parts book. I had to replace mine ~15 yrs ago for hard starting.
--maybe a fuel level higher than the engine.
--maybe a leaky injector.

If there is a venting problem AND a check valve problem maybe the fuel could back track to the engine from the:
--check valve allowing fuel back. It should not if working well.
--from pressure from a pressurized tank even though low pressure. Fix it.
--a return line dip tube below the fuel level.
--maybe tank fuel level higher than engine. With a return line dip tube this would not be needed as long as the dip tube remained below the fuel level.

Look for that check valve and replace it. Cummins P/N 178079

If you have not yet gotten a v555m parts manual go to Boatdiesel and join so you can download the Owners and Operators manual and the Parts book I posted years ago. The Owner/Operator manual is posted in 5 parts. The parts book is the sixth.

I would suggest that you also keep an eye out for a used set from Ebay but the above will help a lot.

As suggested you should be perusing Ebay also for an operators manual
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Old 03-24-2018, 07:16 PM   #34
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Scania and Deere both have current model tier III maine engines that utilize unit injectors. They are electronically metered and timed, but it's the same fundamental concept with a cam driven unit pump to reach injection pressure.
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Old 03-24-2018, 08:13 PM   #35
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I get the whole unit injector design, but reiterate I am a total amateur with the specific designs and variations. I have looked pretty closely at Scania's current unit injector design since I'll be using it, but that's the only one.

I thought that all injector "tips" have pressure activated valves at the end. That's what ensures a build up of pressure before they spray, and enough pressure to get a good spray pattern. The pressurized fuel may come from the plunger in a unit injector, from a high pressure common rail pump, or from a conventional injection pump. But in all cases, you need to hit the injector nozzle with high pressure for it to open. When injectors are tested, the pressure at which they open is tested, as well as the resulting spray patten. So given this, I would have thought that pressurized fuel would be required to push any past an injector nozzle, regardless of the injection system type. I didn't think there was ever a case of any sort of open valve that could result in fuel flow unless the fuel was also pressurized to injection pressure, which is way higher than he head pressure of any fuel tank

Is this not the case? Again, I'm no expert. But maybe one of our diesel gurus can help out here?

I'll take a bit of a stab.
The PT pump supplies fuel to the cylinder heads in a gallery common the all injectors. It is pressurized to several hundreds of pounds but varying depending upon engine speed. When the injector is actuated there is valving internal to the injector which isolates the the injector from the gallery and then pressurizes the fuel as it injects up to ~ 20,000psi. At a certain point another valve function bleeds excess fuel back to the return line.
Unlike the more common injector pump the real pressure is developed at the injector from the camshaft.

Paul Foulston had a name for the action, which I cannot remember, but it was fast, abrupt and effective.

I have read the operation but it was a long enough time ago now I don't remember all the details.
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Old 03-24-2018, 10:16 PM   #36
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Excluding the 555 OP dilemma for a moment -

My engines, not unusual to most marine diesels, has a lift pump feeding the on engine filters and in turn the injection pump. Fuel tank level when more than 1/2 full is above the on engine filters and above the lift pump.

When the bleed screw on top in final filter assembly is opened, fuel never ever flows out unless hand priming the the lift pump lever. This suggests that fuel cannot "leak" past the lift pump or defective injector when fuel tank level higher than injection pump.

In the 555 case it should be easy enough to check the shut down engine for gravity based fuel flow past the on engine filter and before the lift pump. In other words, could the engine be self priming?

Also Seafever, do you have an electric fuel pump feeding the engine?
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Old 03-25-2018, 06:58 AM   #37
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In the 555 case it should be easy enough to check the shut down engine for gravity based fuel flow past the on engine filter and before the lift pump ( insert - injection pump ). In other words, could the engine be self priming ?
In above post #36 I meant to say injection pump as shown
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Old 03-25-2018, 11:16 AM   #38
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I'll take a bit of a stab.

The PT pump supplies fuel to the cylinder heads in a gallery common the all injectors. It is pressurized to several hundreds of pounds but varying depending upon engine speed. When the injector is actuated there is valving internal to the injector which isolates the the injector from the gallery and then pressurizes the fuel as it injects up to ~ 20,000psi. At a certain point another valve function bleeds excess fuel back to the return line.

Unlike the more common injector pump the real pressure is developed at the injector from the camshaft.



Paul Foulston had a name for the action, which I cannot remember, but it was fast, abrupt and effective.



I have read the operation but it was a long enough time ago now I don't remember all the details.

This is my understanding too. But I've additionally always understood that as part of all these systems, the actual nozzle tip is essentially a pressure relief valve that only sprays when the fuel is under high pressure. One of the checks of an injector nozzle is the drip rate which is the leak-by rate.
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Old 03-25-2018, 11:18 AM   #39
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Sunchaser,

YEs they are. Unlike many if you get the fuel close to the PT pump the engine, when cranked, will start without the usual priming or undoing of injectors. These systems will clear the air of the lines.
Typically I use a small electric pump to fill my BIG filter and then crank the engine. It will finish the job on its own which is what I used to do.
I finally used a modified method to ease that process on the starter but yes the engines will self prime.
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Old 03-25-2018, 12:09 PM   #40
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Sunchaser,

YEs they are. Unlike many if you get the fuel close to the PT pump the engine, when cranked, will start without the usual priming or undoing of injectors. These systems will clear the air of the lines.
Typically I use a small electric pump to fill my BIG filter and then crank the engine. It will finish the job on its own which is what I used to do.
I finally used a modified method to ease that process on the starter but yes the engines will self prime.
C lectric

Is it possible that for whatever reason an electric fuel pump was activated (or not shut down) and fuel flooded the engine? Which is why I asked if the engine in question has an electric fuel pump.
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