universal m-25 mystery

[davewin]

I have a 1986 Catalina 30 with the M-25 diesel. The last 3 trips I have made, the engine has either stalled out or lost power after about an hour of motoring.

I replaced the primary and secondary fuel filters and all hoses between the tank and the engine. The fuel coming out of the tank looked clean (I drained quite a bit of it out when I changed all of the filters). After doing so, I put in fresh fuel and ran the engine for about half an hour, at least 5 times at the dock. The boat ran fine, and I thought the problem was fixed. The next time out though, after about an hour, the engine started to lurch and then the RPM's went way down. I throttled back to a fast idle and the engine kept running, but whenever I tried to give it more throttle, it threatened to stall. I made it back to the dock, shut it down, and then tried re-starting the engine - it started fine, and I could get higher rpm. This problem only seems to occur when running at cruising speed for about an hour. I've had the boat for 5 years and this is something completely new.

Some possible related factors are: 1) I recently replaced the heat exchanger with a new one (2") and since that time, the engine runs quite a bit cooler than it used to - I assumed that's because it's winter, and the water up in BC is very cold right now - the problems do seem to have started since then, so could it be a temperature issue?. 2) The tachometer is acting strange, either misreading RPM's and sometimes going in reverse - is that a sign of something or completely unrelated?

Ultimately, I'm stumped. I don't know why it runs fine at the dock and for the first hour of the trip, and then starts acting up. The water was flat calm this last time and I had a full tank, so I wasn't stirring up the fuel (and as I say, the filters are all brand new). Has anyone else had this problem, or have any ideas as to the cause?

Thanks
Dave

 

[Stu Jackson]

Is your fuel pump ahead of the primary filter? i.e., between the primary filter and the fuel tank?

Also, sometimes when you change thew primary filter the seal isn't made and air can get introduced. One of our skippers had a tiny ding in the primary filter element and had the same problem. Assure that the can and the seals are OK.

Or, you're getting air in somewhere.

 

[Maine Sail]

If you have not already remove the screen from the end of the pick up tube in the fuel tank...

 

[fortitude]

Stu is on the right track. Also, check the cleanliness of the fuel tank and if the screen hasn't been removed from the fuel pick up tube in the tank, then remove it.

 

[davewin]

Is your fuel pump ahead of the primary filter? i.e., between the primary filter and the fuel tank?

Also, sometimes when you change thew primary filter the seal isn't made and air can get introduced. One of our skippers had a tiny ding in the primary filter element and had the same problem. Assure that the can and the seals are OK.

Or, you're getting air in somewhere.

Stu

My primary filter (Dahl) is between the tank and the fuel pump, as per normal. It looks as though it is assembled correctly - but how would I know for sure? I always thought that if air was getting in the system, the engine wouldn't start at all - not start, run for an hour and a half, and then quit. Is there a way to test for air leaks while still at the dock?

I did check one other thing out today - the engine kill cable. It is possible that when I installed my new heat exchanger, I inadvertently changed the angle that the cable pulls at, thereby not fully disengaging the kill lever. I re-aligned the cable and made sure that it was not binding on the lever. I then started the engine (no problem), ran it for 20 minutes, and then started it up again. I did the start / stop thing a number of times and everything seems to be running normally. In fact, my operating temperature seemed closer to what it should be, than before I made the adjustment to the cable. If this was indeed the problem, I still don't know why it only happened after motoring for 4 miles (vibration maybe?).

 

[Tom J]

Have you checked the vent for the fuel tank? If it is blocked, a partial vacuum could be created in the tank as fuel is consumed, preventing fuel flow. I've seen this a few times on older cars and trucks.

 

[Stu Jackson]

Dave, you have to follow the hoses from the tank. The kill handle goes to a small spring loaded box on the starboard side near the front of the engine. If you work that cable make sure it return properly at the engine side. You do have the blow up diagram of the engine and a manual, right? www.marinedieseldirect or here: http://www.c34.org/wiki/index.php?title=Main_Page scroll down to engine and fuel. You might also be interested in the engine items in our C34 Critical Upgrades topic: http://c34.org/bbs/index.php/topic,5078.0.html Did you check the filter? One of our skippers strongly suggests that you never do two things at the same time,'cuz if something goes wrong you won't know which is the culprit. Air leaks? Soapy water, but hard to see on suction leaks. But before you do that, take the boat out again. This idea of "It worked at the dock but won't when I'm out" is such a repetitious issue that I wonder why people still do it. Good luck.

 

[LastBoat]

Dave,
I once had a similar problem with my M35B. I was advised to completely fill the primary filter so that fuel would overflow as I replaced the filter top. This would eliminate any opportunity of air entering the system. I always thought the electric fuel pump would totally fill the filter. This did end my problem. I hope it will work for you.
Nelson
C-350 (#345)
Last Boat

 

[davewin]

Gang

Thanks for all of your prompt advice. I'm going to check my tank vent for blockage, check the fuel pickup tube for one of those annoying strainers, and then drive around the harbour in circles on Friday for an hour or so - I'll report back on my success or failure, and whether I have to paddle back to the marina.

As Stu suggested, I might normally try a more systematic approach and tackle one problem at a time - but I do have a weekend away on the boat at new year's planned, so I'm now trying the shotgun approach where I throw everything at it and hope it works. I suppose at the worst case, I could get towed back by a power boater but that's really not the ideal way to start the new year for a sailor.

I'll keep you all posted on my progress (or lack of)

Happy Holidays from Vancouver

Dave

 

[Lindcat]

Hi Dave, my first thought would be to check all of your fuel line clamps for tightness. An air leak could be the culprit. Another problem could be a failing fuel pump, or the screen/filter in the bottom of your fuel pump could be occluded. This is commonly overlooked. Happy Holidays and fair winds to you. Lindcat

 

[pk104]

I would buy a fuel pump( but not from Torresen, to much money for no reason). I had a very similar problem until I replaced the pump. You can have it on board while trying everything else and can change it if needed even when away from your dock.

 

[pk104]

One other thought, my 1986 had a fuel bleeder valve/wheel on left front of engine that was very helpful for getting the air out of the system. Are you sure it is closed?

 

[skookumchuck]

I had the same problem... found out that I had algae and water in the tank that just made me spend money on filters. I suggest a tank polish.

 

[davewin]

mystery solved - almost

An update on my intermittent engine problem:

I checked the pickup tube going into the fuel tank. There was no screen, but a previous owner had added an extra bit of hose so that it would draw from the absolute bottom of the tank instead of an inch or so above - I got rid of that. Then I researched my fuel pump and found that it is an aftermarket automotive pump with an attached, non serviceable, mini filter which probably was ancient. I removed that filter, fired up the engine and it sounded great. I traveled 10 miles to my New Years destination and I was getting an extra 3/4 knot of boat speed above what I had been getting recently. I thought the problem was fixed and was halfway back home when it slowed down, surged, sputtered, and died. I went though the bleed procedure, it started up again, ran fine and I made it back with no further troubles.

I think the original problem did start with the filters, and that when I changed out the primary unit, I didn't get a proper seal, allowing air to get in (as was suggested in previous replies) - that seems most likely now, since a quick bleed got it working again right away. I must be slowly sucking air into the system which, after running for a period of time, builds up to the point where it kills the engine.

I'm hoping this is the end of the story - thanks for all the advice.

 

[Coriolisbc]

Thanks for the posts Dave, I am going to copy, print and keep aboard the boat in case it is my turn next.

 

[tsatch]

Is your fuel pump ahead of the primary filter? i.e., between the primary filter and the fuel tank?

Also, sometimes when you change thew primary filter the seal isn't made and air can get introduced. One of our skippers had a tiny ding in the primary filter element and had the same problem. Assure that the can and the seals are OK.

Or, you're getting air in somewhere.

Do you have an electric fuel pump?

 

[tsatch]

I have a 1987 30 ft Catalina with M25 Universal diesel with electric fuel pump installed between the fuel tank and water separater/primary fuel filter.
Are you aware of the screen filter installed within the fuel pump? If your pump is the same as mine you will note a large hex nut located on the bottom of the pump with facilites removal of the bottom part of the pump. When the bottom is removed you can remove the small filter with your finger. Don't be surprised if it's difficult to remove as it may be so full of crap that it doesn't look like a filter any more - I know mine was. After removal clean it with water and a tooth brush, it cleans up well. If you choose to buy a new one as a spare it will cost approx. $40.00 including rubber gasket. (Universal Part No. 300128/Westerbeke No. 35920). You can view this part in Torresen Marine Inc. exploded diagrams.
I haven't seen this part mentioned in any of the other suggestions. This filter is considered to be the filter that nobody knows about.
Good Luck.

 

[jrowan]

I hate to admit it, but most times that I've had an engine cut out & die on me on the water, it was usually after some "preventative maintenance." I do change my oil & fluids regularly & I am religious about winterizing all plumbing systems on my boat. But when it comes to the fuel system, I try to keep the tank topped off with clean fuel, and I don't fix it it if ain't broke!

 

[Nelsonhow]

Did you check that the tank vent is not clogged?

 

[Stu Jackson]

I have a 1987 30 ft Catalina with M25 Universal diesel with electric fuel pump installed between the fuel tank and water separater/primary fuel filter.
Are you aware of the screen filter installed within the fuel pump? If your pump is the same as mine you will note a large hex nut located on the bottom of the pump with facilites removal of the bottom part of the pump.

I haven't seen this part mentioned in any of the other suggestions. This filter is considered to be the filter that nobody knows about.
Good Luck.

For many,. many yerars we have been suggesting that the fuel pump be placed AFTER the primary filter to avoid clogging this little filter.

You may be interested in this "Critical Upgrades" topic, with much information about your engine:

http://c34.org/bbs/index.php/topic,5078.0.html

...unless I've posted it here earlier...:naughty: