Confounding Diesel Problem - Looking for Ideas

[Boracay]

There is a reference in the Westerbeke FAQ to a situation where the engine temperature creeps up. Is it possible that your problem is temperature related?

There is a reference to a similar problem here.

If there has been a problem with biomass then replacing all fuel lines and cleaning the tanks may be a good idea.

[DeepFrz]

I agree with you on the filters. As long as the pressure gauge is in the operating range it will not cause this problem. Did you say that you had checked the pickup tube? If not then I agree with previous posters that there may be a screen that is mostly clogged or as Boracay points out, a partially clogged fuel line.

[MarkJ]

Originally Posted by SoonerSailor

There was a lot of biomass in the fuel at that time, .

Do you use a fuel treatment that includes water absorbing properties?

I've heard some of those products when they convert the water they make a goop that sits in the bottom of the Racor but can't be seen because its clear.

I'd still be cleaning and scrubbing all the simple stuff first. I know when something goes wrong on my boat its normally the boring drudgery work that needs to be done, not the purchase of a shiny new bit of kit.

[S/V Antares]

fit a clear hose between the racor and the lift pump. Ifair is the issue you will see bubbles. If you do .... fit it between the racor and the tank to see where it comes from.

2 micron is too small. use a 10 micron on the racor and the engine filter will cover the small stuff. Remember that there is a filter in the bottom of the pump (westerbeke round pumps)

[cwyckham]

I believe you said you knew it wasn't in the tank because you can switch tanks and have the same problem. But aren't both tanks built by the same people in the same era? Could they both have clogged filters on the pickup?

[Marqus]

The OP stated that the problem ONLY arises after the engine has run problem-free for 1 to 3 hours. He initially suspected biomass in the fuel tanks, but then eliminated that as a cause.

So, if filter micron rating is the problem, why would it suddenly become a problem after the engine has run faultlessly for 1 - 3 hours, and not before (a fuel tank can be stirred up in less than an hour).

Furthermore, if filter clogging is the problem, why would the vacuum gauge on the Racor not give a commensurate indication?

Not just being sceptical here - I'd like to understand, given the above info, how filter choice can be the cause of his very specific combination of symptoms.

[SoonerSailor]

My thoughts parallel those of Marqus. I also feel I have eliminated tank pickup problems (like a clogging screen) because the Racor pressure gauge does not reflect a developing drop in pressure. I've tested this by closing off the fuel supply between tank and filter block, and the Racor gauge starts moving out of the black while the engine continues to run fine for a bit longer. And of course switching to the other tank makes not one whit of difference.

If the engine begins to stumble or quit after running for a few hours (note that engine temperature gauge stays in its normal position), I can shut it down and wait an hour or two, after which it seems to run fine for another hour or three.

If right after the engine starts having trouble, I kill it and run the engine fuel pump for a 10 to 15 seconds then try to restart it, it continues to have the problem. Again, if it sits for an hour or so, I can restart it and everything is fine for a while.

The Racor 500 filters glasses are not collecting water - though they did after we first got the boat and before the first fuel polishing which included a tank cleaning. They are still collecting some sludge in the settling bowls, but not water.

We used Biobor after the first polishing, but the next mechanic said don't use biocide - use Startron with every fill. The next mechanic swore by Service Pro or something like that. Everyone seems to have a different opinion! I know Westerbeke suggests both a biocide and a cetane booster.
Chip

[doug86]

Originally Posted by SoonerSailor

If the engine begins to stumble or quit after running for a few hours (note that engine temperature gauge stays in its normal position), I can shut it down and wait an hour or two, after which it seems to run fine for another hour or three.

If right after the engine starts having trouble, I kill it and run the engine fuel pump for a 10 to 15 seconds then try to restart it, it continues to have the problem. Again, if it sits for an hour or so, I can restart it and everything is fine for a while.

Those are the classic symptoms of a clogged pickup tube. I know you say the racor gauge shows no restriction, but I would pull the tubes just to eliminate those once and for all.

Other thoughts: some clog at the output of the Racor, or something fouling at the mechanical lift pump. The circumstances you describe are a fuel starvation problem. I don't think it's caused by air in the system.

Only way to isolate this is to hook up a 6 gal outboard tank with fresh fuel right to the main injector pump and see what happens, then continue connecting it further and further upstream (towards the tanks) until the problem reappears.

[Cheechako]

Are you sure your temp gauge is working properly? Sounds a lot like an exhaust restriction...? If I remember right you have check for venting and no restriction...? If not, when it dies, open the fill cap and see if there is a vacuum...

[Jesse]

Doug86 has a solution to the problem that is both simple and elegant. If it doesn't locate the problem it should eliminate the fuel system as the source. Jesse

[Capitain Mike]

Originally Posted by Tempest245

IF The 10 micron fix works...I said it first....

If it doesn't...it was Mike's advice...

Doesn't really matter who said what as long as he can fix the problem. You can have all the credit.

[doug86]

Originally Posted by SoonerSailor

If right after the engine starts having trouble, I kill it and run the engine fuel pump for a 10 to 15 seconds then try to restart it

WAIT! An electric fuel pump? They have a screen on the bottom. I bet that is clogged. Very common problem.

[Capitain Mike]

Originally Posted by doug86

WAIT! An electric fuel pump? They have a screen on the bottom. I bet that is clogged. Very common problem.

borrow a pump and try it with the borrowed pump. may have an intermittent electrical fault. If not put an inlet and an outlet on the pump and into a bucket of diesel then run it for the required length of time see if you can recreate the fault.

[Capitain Mike]

Originally Posted by doug86

WAIT! An electric fuel pump? They have a screen on the bottom. I bet that is clogged. Very common problem.

"When one is willing to go without, then one is free to go." - doug86
"If you love your boat and love your wife and you could only have one of them which would be your choice?"

[SkiprJohn]

If it starts and runs for awhile I don't believe it could be air in the fuel lines. I'd eliminate that. If it starts and runs until you start bouncing around in the ocean then I'd think the fuel pickup line in your tank is sucking up something stirred up from the bottom of your tanks that blocks your pickup tube but I don't think that's it either since you are getting good readings from your gauges at the filter.
Can't wait to find the real answer!!!!
kind regards,