Volvo MD1 won't run under load.

Yes, it's a 42 year old engine! I'm a sailor not a mechanic. My son-in-law tried to help me out by cleaning out the cooling water passages, testing the thermostat, repairing and remounting the thermostat housing - all because I was convinced that it was overheating. I started the engine and ran it at varying throttle positions in neutral for about 15 minutes. So it's not overheating.
Yesterday, I went out for a sail and when the wind died I started the engine to go back to my mooring. As soon as I put it into gear I could hear the rpms begin to slow. I advanced the throttle but within 3 minutes it died. I sailed (very slowly) for a few minutes, restarted the engine but it quit again within a minute or so. Tiptoed up to the mooring eventually.
We have the original user manual, service manual and parts catalog that came with the boat & engine.
Where do I start to diagnose the problem(s)?
Thanks in advance for looking at my post and considering it.
Maureen

Sounds like a fuel supply problem. Change fuel filter and bleed system according to manual.

Thank you Glen. I will do that tomorrow.
I've been reviewing everything I've done since the engine last ran well. I winterized it in the Fall of 2011 as I usually did, removing as much fuel from the system as I could. The 5 gal. cylindrical tank is mounted high under the aft deck with a shutoff as it exits the tank. From there it went to a CAV twin simple sedimenter/water separator unit and from there to the Volvo fuel filter and then to the fuel injector pump. That twin setup is essentially 2 sedimenters in series on one head. The fuel plumbing lines are all copper. In the spring of 2012 I found that one of the glass bowls on the sedimenter unit had cracked and would no longer hold fuel. No replacements to be found anywhere! I chose not to bypass the broken one because I didn't know how to make the connections!
I found a source on the internet www.abcprecision.com that made an adapter for old CAV filter heads to allow them to accept a screw on filter. By the time I ordered it and dry fitted it, it was late in the season so I decided not to launch until 2013.
This year I fitted it according to instructions, and had a difficult time getting it tight enough to not leak. I think it still has a very slight leak between the adapter and the CAV head. It ran fine on land and at the dock but when I put it in gear it runs for a varying amount of time, minutes or seconds, then quits.
As I went over everything I could find in my engine documentation and diesel fuel system booklets I occurred to me that I have added another

layer

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of pleated paper filtration between the fuel tank and the pump; maybe that is choking the flow down too much? Not sure of how to test for that. Maybe I can take out the engine mounted filter, reconnect and see if that makes a difference, before I replace it with a new one. I will also look more closely at how the metal fuel line connections are made. Maybe I can bypass that broken unit entirely. Or????
Here's an old drawing of my boat and a picture of the open circular hatch in the aft deck. The fuel tank is mounted to the port under side of it.
View attachment 7437View attachment 7438

One way to determine an air leak or fuel starvation is to run the fuel return line into a separate container. Check for a good flow. Also check to see if bubbles are coming out of the fuel line by putting the return line under the surface of the container. Bubbles indicate an air leak in the system. It's process of elimination now. Bypass the CAV system with a temporary line, and do the same with the Volvo filters. If you find the filter base is leaking, I recommend the NAPA 4764 base with a fuel/water separator filter. NAPA parts are good quality and easy to aquire. Keep us posted.

Thanks, I will try all of your suggestions. Just finding the named items in the compartment is a job. Have to lie on my side on the quarter berth beside the engine to see it, juggle a light source and select tools. No room to sit up or turn around. Have to wriggle out to get something. Lots of Fun
Someone digitally scanned the original operators book(which I do have) - http://l-36.com/manuals/CAV-Diesel-Fuel-Filter.pdf. The information on original pages 24-25 shows my type of filter and the maintenance for it. First owner of my boat annotated it with the appropriate part#s!
What the illustration doesn't show is the twin setup with one long mounting plate holding 2 of the sedimenters. Note that neither of these have a filter element. Setup worked fine until one of the glass bowls broke. Mine are mounted on the partial bulkhead behind the engine, between it and the rear storage compartment. They can also be seen but not worked on by hanging upside down in that rear compartment which I no longer do!
I also received from the original owner the shop manual and parts manual for the engine but it is also on line - http://boatinfo.no/lib/volvo/manuals/md1-d1-md2-d2.html#/0. In some ways the on line version is more helpful because I can blow up the illustrations.

Onward!

And they say mechanics charge too much.

And the saga goes on...

I realized that I've added an additional filter into a gravity fed fuel system which is probably starving the engine when load is added. Two people suggested adding a small electric fuel pump so I've replace some of the old copper fuel lines with rubber and added a Facit pump. But I don't know how to wire it in! The instructions suggest wiring it into the oil pressure light so it only runs when the engine does. My oil pressure warning light doesn't work! the wire from the sensor on the engine has disappeared and I can't understand the wiring diagram on pg. 20 of the manual to figure out how to fix that either. I need step by step instructions, no abbreviations or symbols.

Any guidance?View attachment 7535

Maureen

I strongly suggest fixing the Oil pressure sensor or switch. With that said, first, using the same size or larger wire that is attached to the pump run the positive (red) wire into a power source that turns on and off with the key. Make sure the place that you hook the positive (red) wire, has a fuse in between that point and the battery. If you would like to tie an oil pressure switch into the circuit , run the ground wire (Black) to a pressure switch that is plumbed into the oil circuit. Be sure not to use Teflon tape on the pipe connection, this will interfere with the ground. I will post a part number for an oil pressure switch that you will be able to use. Hope this helps.