Diesel Intermittent Problem

[Jack Baker]

I have a Vetus 3 cyl. diesel which I have run 25 hours over the past few weeks on a cruise. Once the engine stalled, and once it lost power briefly then resumed operating at 2000 RPM. No huge problem but something is causing these symptoms.

After the first stalling problem I checked the fuel water seperator and found small black deposits in the fuel (no water) which I believe is some type of algae. Added a bio treatment to the tank. The second occurence was later in the trip. I put new filters on annually, and will change filters again prior to resuming the cruise.

I read past posts on cleaning the tank (generally recommended having it cleaned professionally).
Any other words of wisdom from the experts?.

[Donn]

Jack...how old was the fuel? If it was new, was it from a reliable source? What sort of filtering system do you have for the engine? I use 2 filters on each engine, the primary is 12 micron, and the secondary is 2 micron.

[John E Hardiman]

Jack: When was the last time you drained the tank? Most tanks breathe somewhat due to temperture, pressure, etc. Water vapor gets in and condenses. The more air space in the tank the worse the problem. As the fuel is lighter, the water (and debris in the fuel) collects at the bottom of the tank. And yes, sometimes things will grow at the fuel/water interface. Most commerical systems have drains or water seperators to combat this. Really slick systems have fuel tanks>primary fiter>setteling tank with drain>secondary filter/water seperator>day tank> final filter>engine.
What is insidious about it is that the fuel pick-up is generally placed above the tank bottom to avoid this problem. However, if powering in a seaway, the fuel gets stirred up and water/debris is sucked up into the fuel pick-up.
Know of a sportfisherman with twin diesels that the owner let sit with almost empty tanks over the winter. Spring came and he put 750 gals in. The 200 mile run out was calm, but a strong sea came up. Of couse the engines died, filters clogged. It was watch and watch at ~4 knts back in clearing the filters as one engine would only run about 5 min before the filters would fill up. LONG trip back in head down in the engine compartment :( .

[Jack Baker]

Donn and John,
The boat was built in 1959 with a Gray Marine gas engine, and repowered in the mid-80s with the Vetus 3cyl diesel. The fuel system is as follows:
1) 25 gal tank with fuel flowing from valve at lowest point (not a higher pickup as noted in other posts). There is a drain valve at this point. This is likely the original tank as it is under the port cockpit seat and would require major rebuilding to remove it.
2) Bronze fuel/water separator adjacent to tank, I drained some fuel here and noticed the black crud in the fuel, then added a bio treatment.
3) Second fuel/water seperator (Vetus RTPBAF100).
4) Vetus Fuel Filter (RTPBAF110).
5) Transfer pump to supply fuel to engine.
6) On block filter (Fram c1191A).
7) High pressure pump, injectors, etc).

The engine burns @ 1/2 gal/hour I have used approx. 15 gallons this season. (2/3 tank capacity). I have been muying fuel at Marinas along the way so I can not attest to quality of the fuel. My plan is to replace all the filters and then continue on the cruise. I have not drained the tank as I am not quite sure how to go about it, other than using small capacity (1-2qt) contained and let it drain via gravity.

I spoke to the local NAPA folks this morning and they suggested fileter change, continue bio treatment (say it normally works well in removing algae/sludge) and adding a fuel conditioner (adds sulfur among other things).

Thanks for the help. Let me know if you have additional thoughts.

[Donn]

I drain my tanks with a pump, running the intake hose down the fill pipe. The pump is similar to the old fashioned hand-pumped bilge pump that looks like a bicycle tire pump.

[On Vacation]

Do not overtreat the fuel. It will be worse if you are trying to work it through the system with the fuel filter changing. If you can get to the top of the tank, drain it and clean it. If you don't have inspection plates or no access, then pump it or have someone in your area pump and recycle the fuel through an auxilary fuel filtering system that many have that do this for a living.

The bronze filter mounted adjacent to the tank engine sounds like a Racor fuel filter. Those are expensive so it maybe in your favor to have it pumped out. This maybe the way to go so you don't get caught stalling out in the worse time, like docking next to your friends million dollar boat.

Also in the future keep your tanks as full as possible, especially in the winter time so the sweating in minimum.

[John E Hardiman]

Jack: Get a small container and bleed some fuel out through the drain valve you mentioned. If it is anything other than pure, you have to either continue to bleed until it is or pump the tank and have the fuel "polished". As you are on a cruise, it's your decision when and where the tank gets cleaned, but as a note: all small aircraft are equiped with fuel tank gravity drains and the FAA REQUIRES that part of the pre-flight is to open the drains until pure fuel comes out. Seems that more than one person has plowed one in due to this problem.

Otherwise; back to the problem of stalling and loss of power. I am unfamiliar with your engine type but other things to look at from my experince that can cause quirky behavior are:
fuel return line check valve (if it has one)
electrical connections to the injectors (if they are electrical)
worn/dirty rack on machinical injector pump
glow/spark plugs
boat trim and its effect on the wet muffler/exhaust location (I've seen problems if the water head got too great)

[David Tabor (sailordave)]

My sailing association had a problem w/ the diesel stalling out on one of the boats. Would run fine for a while... then nada. Finally it was figured out the at the drain on the RACOR filter had been overtightened, like someone really honked down on it and squished the O-ring. To the point that it shredded and was allowing air to bleed into the system. That doesn't account for the little dots of crud in your system but you may be dealing w/ multiple problems. More than once I thought I've solved an issue and found a second fly!

[Andrew J. McGrorty]

it hasn't been mentioned but when you add a biocide it kills the bugs but their dead bodies are still floating around in the fuel. you could put on a 30 micron primary filter on the racor 'til you feed almost all 25 gallons of fuel through it. then change the filter again when you fill up with fresh fuel. andy

[Carl Stone]

Just a thought, since all but one answer has been about fuel. I had the same problem, and it turned out to be minute air infiltration. Will shut you down, then run like nothing is wrong. Check all hose ends and lengths throughout the system, if any ends look old, cut off the last inch or so and refit. Hadn't heard about the wing nut before, going to check mine tonite!

[Bill Dodson]

This is an article about diesel fuel problems and solutions: TrawlerWorld Article (http://www.trawlerworld.com/c_features_06.htm)

[imported_Krueg]

I just went through this with my boat. I ended up pumping all the fuel out into cans. Then, I pulled the tank (sounds like this isn't an option for you), and cleaned it out with a pressure washer and detergent. I rinsed it repeatedly with water, and followed up with rubbing alcohol to assist with evaporation. I've now had the tank back in about three weeks and absolutely no problem. I have the peace of mind that a clean fuel system will give you.

You could plumb a pump inline with your fuel filter bypassing the engine and returning straight to your tank. Keep circulating the fuel and change the filter element as necessary. A friend of mine used this method and it worked well for him. It's basically what the fuel polishers do.

I think the easiest thing might be for you to hire a professional fuel polisher. For a 25 gallon tank it shouldn't be that much. Get it taken care of quickly and resume cruising. Good luck.

Eric

[Jack Baker]

Thanks for all of the suggestions, here's what I discovered:
1) Following the recent symptoms (loss of power) I took fuel samples at each stage of the fuel system (where practical) The initial f/w separator had a cup of sludge,evidently stirred up from the tank during a rough crossing the prior day.
2) I hired a mechanic who had the right tools to pump out the tank. He brought a 50 gal drum, oil boom for any leakage, and electric pump. We were able to get good access through the filler tube, particularly to the low spot in the tank and also back flushed the tank. He charged me $125 to do it.
3) Again took samples, had clean fuel at each location so I decided to wait on the filter change. (10 years ago I had caused a plugged injector during a filter change, and didn't want to cause a problem 150 miles from home).
4) The engine ran without a hitch (17 hours) during the remainder of the trip home with nor further symptoms.

Lessons learned:
1) Get the tank pumped out when first recommissioning an engine that hasn't been run in a while and the fuel is old (or unknown).
2) Establish a regular schedule for removing old fuel. On an engine that uses 1/2 gal/hour with a 25 gal tank (that never gets below 1/2 full) the age of the fuel can be a problem.
3) Continue regular filter attention.
4) Check f/w separator each day, particularly if in rough conditions.
5) I also bought a book today on Marine Diesel Engines. I have been much more focused on other aspects of the project and need to improve skills.

Thanks again for the timely assistance. It pointed me in the right direction and avoided other problems (I am sure) during the remainder of the cruise.

[Gene Cramer]

Jack,
Sounds like you have your problem solved.
In your "lessons learned" add: check the fuel tank pick up screen. It doesn't sound like you have one but I have seen a lot of money waisted on mechanics when the only proplem was a cloged fuel pick up screen.

Gene Cramer
Cramer Marine
Milwaukee, WI