Engine won't run. Solinoid Valve?

[Gummy]

Hi,
I have been battling my Volvo MD-6A for couple months now. I got the engine with a new to me boat a couple months ago. The engine would only idle slowly and die after a few seconds. I eventually sent my injectors out for rebuild and found that the timing was a bit off. After replacing injectors and adjusting the timing, the engine started and ran very well. I then found that the water was not circulating so I shut the engine down using the solonoid valve. I ran really well twice for about 2 min. After I finally fixed the water issues(and a couple weeks) I tried to start and it is back to it's old ways.

The system has been bled repeatedly and the fuel appears to be quite clean, I even installed a temporary electric fuel pump.

If I squirt raw diesel in the intake while cranking, the engine runs until I stop squirting then stops.

I pulled the injectors and hooked them up and cranked the engine. They are working very well when out of the engine.

Do you think the solonoid valve could have a part inside that is sticking in the shutoff position? The lever is clearly in the run position. I tapped the outside too to try to shake it loose inside. Didn't work... I think these valves work by adjusting the timing right?

BTW, when I got it the fuel was really ugly and black. I drained the tank, installed a huge Racor filter and changed the fine filter and the fuel pump filter. I mention this to let you know the injector pump probably had dirty fuel in it. Thanks for any insight on this stuff,
Rod

[superdave]

The idea that when you spray fuel into the intake and she runs clearly points out that the engine is not getting fuel. Since you mentioned the black fuel, and the fact that the engine could originally only run for a few moments, it suggests that a filter or something similar is blocking the fuel line somewhere.

It wouldn't surprise me to find that the fuel tank was too polluted to be cleaned by simply draining it; perhaps some gunk is still in there? Check the new filters for clogging. Assuming that the fuel tank was the original culprit, work your way from there to the engine, checking filters/fittings/etc., and perhaps find some way to draw fuel through from the tank to wherever you can take it apart - this may help you find the CURRENT clog. But my bet is that the tank is still spitting gunk into the fuel lines, and this would have you cleaning the filters very often when it really just needs a serious flushing of the fuel tank.

Don't worry, someone who actually knows this engine will probably come along soon. My guesses are based on my experience with car engines... valid stuff, but there are many differences!

Good luck!

-Dave

[superdave]

Hold it - I just realized that diesels can use a solenoid-actuated fuel switch - I thought we were talking about a starter solenoid! Beyond my not knowing how the solenoid operates, I see that you say the injectors work fine out of the engine, and so I think I was on the wrong track there... but truly, squirting the fuel into the intake suggests the engine is not getting fuel somehow.

Sorry to have misled!

-Dave

[Gummy]

Yeah, I am talking about a shutoff valve that is located on my injector pump. I don't have a solinoid on mine but I think it is called a solinoid valve because some engines have a solinoid on the valve so it can be switched remotely. Fuel is flowing all the way through the system as far as I can tell. Thanks for the reply.

[Faster]

If you are absolutely certain that fuel is getting to your injectors then the fuel shutoff valve is open.

Perhaps you have a still - uncorrected fuel quality problem.

[rewell6]

I agree with Faster. Most likely you still have a fuel problem.

Probably several problems all at once. Makes it very frustrating to figure out, so take your time and think. Diesels are actually easy to get/keep running. You need a good battery (or two) and a good starter to spin the engine over fast enough. Second - the glow plug circuit has to be working. Third - fuel

0. If you have even the smallest air leak in the lines it will run like that. Could even be that one of the injectors is leaking internally. Or you are losing prime to the fuel pump. If there is an air leak before the injector pump and it sits for awhile the fuel will drain back to the tank and when you try to run it has just enough to make it cough then dies. I had this problem on a 6.2 GMC, took me a month and a half to figure it out. I had to prime every day.

1. The electric fuel pump could be giving trouble. If the fuel pump has vanes it will not work if even the smallest piece of trash gets caught in one of the vanes. I know - don't ask. ok - stranded on a lake for hours waiting on someone to come by and tow me back. The local marina that was open didn't even have a tow boat service.

2. Algae that was still in the fuel lines clogged the electric fuel pump or the injector pump.

3. Injector pump weak. Could have enough pressure to spray, but not enough to work correctly. It is possible the injector pump does not have enough pressure to open the rebuilt injectors correctly. Depends on how old it is and if it has ever been rebuilt.

4. Timing. I found this site about timing the MD6A
http://www.marineengine.com/discus/m...94/26433.shtml

5. You bled all the fuel out already?

I know a good shop if you need any parts or anything rebuilt. (In-laws)

[Gummy]

Thanks Faster and Rewell. I have 3 batteries, the starter is not super fast but when I use the decompression lever, it spins up fast then I drop it for start. There are no glowplugs on this engine.

I doubt the injectors are leaking internally as I got them back last week from rebuild. I put the temp electric fuel pump on prior to the engine fuel pump to help ensure I am not losing prime to the pump. I believe(obviously I can be wrong at anything) there is fuel throughout, everytime I loosen a line, fuel leaks out(3-4.5 PSI pump).

I would not be suprised if there was algae or something ugly in the injector pump but it pumps enough to make a great spray pattern through the injectors with them out of the engine. It is very old and has not been rebuilt. I have it off now and wonder if I can have it rebuilt reasonably without going to VOlvo($$$). It is a bosch pump. Without a detailed manual or new seals, I don't want to try it myself. I have a diagram of the inside and it looks like trying watchmaking.

Thanks for that article. I like to collect all I can on this engine.

Rod

[trantor12020]

sound like my friend's volvo engine. spent alots of time & money to replace pumps, filters and injector. finally found a leaky fuel hose.

[Boasun]

Check your fuel system. Be sure to include the fuel tank, fuel lines, filters all the way to the engine.
Have had clogged fuel lines, fouled fuel tanks and filters. Algae grows in the stranges places in the fuel system.
Cleaned out one fuel line of what looked like horse hair. It was algae at its worst. also check for leaks and kinking.
And after every thing is working correctly, change all of the engine filters about every 250 hours. Yah the oil also.
keep your fuel tanks full if you can. Less condensation with a full tank. Thus less water in the fuel and a less medium for algae to grow.
Also see if a rag had gotten dropped in the fuel tank. Found those also... Gets caught in the fuel pick up and blocks it. So the engine runs for a short time then is starved for fuel.

[rewell6]

First check your PM. Shop recommendation that I don't know if I can put here

You can have it rebuilt. The shop that rebuilt the injectors should be able to rebuild the pump too. Don't go through a boat place, they will just send it to a diesel rebuilder. If you are even the least concerned about the injectors, you could just have them tested and make sure they are functioning correctly while it is apart. There is a machine for this.

While the pump is off getting rebuilt clean the lines out. Be careful with the metal lines between the pump and injectors, they have to be a certain length / same length as the others. If you could feed a fishing line or something like it through the lines you could tie on a small piece of gun cleaning cloth and pull it through. Clean all the lines from the tank to the injectors. Don't forget to clean out any connectors. Heck with all this work you might as well clean out the tank and check the fuel pickup screen too.

Change the fuel filter again and make sure the whole assembly is clean.

Either make the electric pump permanent or replace the mechanical pump. No need to do this after you put the pump back and have to bleed the system again.

Fix all this right the first time and you won't have to deal with it for a long time. If there is still a problem it will be an air leak in one of the lines.

One more thing. Don't mess with any other part of the engine yet. From your description it seems to be ok. You don't want to create another problem until this fuel issue is corrected.