Diesel engine losing revs

[coastalexplorer]

In regard to the exhaust elbow, The original part was clogged with carbon and the water jacket clogged with corrosion, It was also slightly cracked. During the process of trying to clean it the cast iron crumbled. Since the new exhaust elbow part from Volvo was so expensive I invested additional money into having it ceramic coated in the water jacket and the exhaust gas passages. My engine is fresh water cooled,

[SteveInMD]

If you have a dirty fuel tank it might take many fuel filter changes before it is cleaned up. Doing a fuel polish is a good idea but you still might go through 6 or 8 sets of filters before it clears up completely. Change both the primary and secondary (on engine) filters at the same time.

[Feluka]

Thanks again for all the responses. I took off all openings on the fuel tank. There is no screen on the intake. Both intake and return are 1/4 " copper pipe in the tank. I accessed the largest opening - the fuel capacity gauge - and attached a clean new cloth to some tongs and sloshed that through the diesel in the tank, scraping the bottom as much as I could. The cloth was really pretty clean when it came out. I was expecting particles or smear to be visible. I also disassembled the primary filter so I could change all gaskets. I changed the primary filter.

I checked the hoses and clamps I could access.

The engine will idle for about 5 to 10 minutes. Then it will run at about 1200 or 1500 for 20 minutes or so before stalling. Each time it stalls I have to set the revs a bit higher in order to restart it. I do not have to prime the engine each time. When running at over 2000 rpm it doesn't stall but will lose revs then pick up again.

I will try to get some of the Archoill additive tomorrow. Someone at the marina here wondered about the injectors.

[Steve Bean]

Fuel tank vent clear?

[SteveInMD]

It sounds to me like to have an air leak. You have fairly classic symptoms. Go connection by connection and make sure all are good.

Also, change your secondary filter. The stuff the clogs up secondary filters is really small. Without a vacuum gauge it can be hard to tell when it's clogged.

[Feluka]

Yes, I am thinking this is an air leak problem too. A mechanic at the marina I am currently at came by and thought the same thing based on the symptoms. He thought the problem was that the lift pump is no longer totally sealed or doing its job. I have ordered a new one and also a new hose that runs from it to the primary filter, as this is quite brittle.

I should have them on Tuesday and will replace them then. Hopefully that does the trick because if it doesn't I am stuck.

[SteveInMD]

I almost posted a suggestion about a new lift pump. If you have a hole in the pump diaphragm, it is basically an air leak.

[sailormed]

I had similar problems, after a full day at a rodeo mooring my fuel had the color of tar. Primary filter changed, secondary filter changed, still no or insufficient fuel flow.
Diesel mechanic called to the rescue identified severe clogging in the 90° bends in the Racor filter housing in the dirty unfiltered fuel lines. Now I know for next time 😡


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[DeepFrz]

Originally Posted by sailormed

I had similar problems, after a full day at a rodeo mooring my fuel had the color of tar. Primary filter changed, secondary filter changed, still no or insufficient fuel flow.
Diesel mechanic called to the rescue identified severe clogging in the 90° bends in the Racor filter housing in the dirty unfiltered fuel lines. Now I know for next time 😡


Envoyé de mon iPad à l'aide de Cruisers Sailing Forum

Keep your fuel and tank clean and there shouldn't be a "next time".

[Feluka]

I'm not sure if anyone is still reading this but I have just returned home and wanted to let those who offered suggestions know what happened.
I installed the new lift pump but that didn't solve the problem. I also had a piece of hose with banjo fitting etc. made up. This runs from the primary fuel filter to the left pump. That didn't fix it, either.
The mechanic at the marina still thought that air was getting in, as did some of you, so went from the tank to the primary filter, replacing or checking everything. I checked the connectors and the fuel pickup for leaks - none. I pulled out the 16 feet of fuel hose and replaced that and I think that was probably it as the engine hasn't stalled since. I motored the length of the Erie Canal with no problems.
Thanks for all the help

Peter

[Badsanta]

Thanks for the update. Good to know

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[daviddiscenza]

Would some please explain the term "polish the fuel".

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[barnakiel]

You run it thru a special set of filters. Often this is done over long time to the same tank, or thru many filters but just once - to a separate tank then back to the original one.

To filter. To clean. To remove water, dirt, growth, etc.

Example:
http://www.powerandmotoryacht.com/si...burn_a575w.jpg

b.

[daviddiscenza]

Thanks, barnakiel.

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