Bleeding Problem (Part 2)

[Jim@sea]

In hindsight when I bought the boat last year I should have put a new engine in and I would have been sailing today instead of being threatened with divorce as every night when I go home I smell of diesel as my wife hates the smell.

When I bought the boat I took a chance on the engine, I went on a sea trial and for 5 minutes the engine sounded great, then it stopped and we had to be towed back.
After fitting a new lift pump, primary and secondary filters complete, new on/off valves, I go to the boat, bleed the engine, connect a hose pipe and it starts. Now runs on tickover for about an hour, then starts to (if it was a petrol engine I would say misfire) then it stops.
It still sound great when it is running.

Could it be the injector pump,
Unfortunately as the Thornycroft 154 (BMC 2.52 Diesel) is in a deep bilge area I cant get the Injector Pump out without taking the engine out which will cost a fortune as where the boat is there are no mechanics.

I have read that if you have an injector pump which may have muck in it or the springs sticking by putting Automatic Gearbox Oil in the pump for 24 hours can clean it.
Is this what I should do or what do you suggest,
Any advice gratefully received.

 

[macnorton]

If it runs ok when it has been bled its not the pump but a fuel supply issue, rig up a gallon of fresh direct to the lift pump and see what happens..

 

[BobnLesley]

If it runs ok when it has been bled its not the pump but a fuel supply issue, rig up a gallon of fresh direct to the lift pump and see what happens..[/QUOTE

I'd agree with that; good advice, take it.

 

[Mrnotming]

Sounds like the suction side of the lift pump is availing itself of some air via porosity in a line or a union.these lift pumps sometimes have a gauze filter,though things are bad if that is choked.The diaphragm in the lift pump may have failed?if the diesel tank level is above the engine it might be an idea to bypass it temporarily? But perhaps the tanks are deep like the engine?In which case the OP's suggestion of a new small fuel supply (of fresh fuel) will tell a lot?
Whilst bleeding a fuel system,some maintain that positive pressure via the filler cap can be a great help,(Swmbo blowing into the orifice,not!)
Or leave the filler cap in place and arrange gentle pressure through the overspill pipe?
Hope it gets solved,do tell us what the problem was?

 

[Caer Urfa]

Sounds like the suction side of the lift pump is availing itself of some air via porosity in a line or a union.these lift pumps sometimes have a gauze filter,though things are bad if that is choked.The diaphragm in the lift pump may have failed?if the diesel tank level is above the engine it might be an idea to bypass it temporarily? But perhaps the tanks are deep like the engine?In which case the OP's suggestion of a new small fuel supply (of fresh fuel) will tell a lot?
Whilst bleeding a fuel system,some maintain that positive pressure via the filler cap can be a great help,(Swmbo blowing into the orifice,not!)
Or leave the filler cap in place and arrange gentle pressure through the overspill pipe?
Hope it gets solved,do tell us what the problem was?

I also agree with Paul and have been horrified when I have seen the filter inside the lift pump which the BMC 2.52 Diesel usually has, my guess is it has never been touched as not everyone knows there is a filter inside.

Good place to start otherwise agree with others and it is a fuel supply problem.

Mike

 

[johnphilip]

Just something I heard today

Buying filters in French Marine today I commented on their display of broken pistons, big ends etc.
The one that caught my eye was a totally blocked exhaust / water injection elbow. I marvelled that the engine had run at all but apparently it had run, on tick over, but as soon as you opened the throttle it died with symptoms exactly like fuel starvation. Unable to clear the cylinders of exhaust gas the engine faltered and died.
Any chance this is the issue here? I admit I know nothing about your particular brand.

 

[Jim@sea]

I also agree with Paul and have been horrified when I have seen the filter inside the lift pump which the BMC 2.52 Diesel usually has, my guess is it has never been touched as not everyone knows there is a filter inside.
Mike

Thank you for the previous photos of your fuel on/off valves and I have changed my single one to two like your set up.
The lift pump is new and I have replaced the rubber fuel tubing.
I have ordered a 12v Electric Fuel Pump which (hopefully) will by by-passing the filters and connecting it directly to the injector pump may reveal if the injector pump is faulty. When I bleed the injectors the last two seem to have less diesel coming out, but that could be a symptom of shortage of fuel.
Mind you, when I bought new CAV type Fuel Filters I wish I had bought these RACOR ones as even though the CAV copies are new they still want to seep diesel and with one the only way I could stop it seeping was to put two rubber rings in instead of one.

 

[paddywackcocker]

Some had a gauze in the inlet banjo at the fuel injection pump, worth checking.
If you are to use a electric feed pump to test, I would make sure it is low presure (2-4psi) otherwise leek off May not cope and you could overwhelm the injection pump seal and end up with deisel in the sump.

 

[Laundryman]

If it runs ok when it has been bled its not the pump but a fuel supply issue, rig up a gallon of fresh direct to the lift pump and see what happens..[/QUOTE

I'd agree with that; good advice, take it.

I don't disagree with this test method but be aware that the gallon of fresh diesel will only last about 5 mins because the rest will be dumped back into the main tank via the fuel return pipe. My guess from your comments re filters is that your problem lies there. Re do the filter and put an outboard type squeezy bulb in the line to help bleed. It makes the bleeding process so easy and will show up any leaks. Good luck. Alan

 

[vyv_cox]

If it runs ok when it has been bled its not the pump but a fuel supply issue, rig up a gallon of fresh direct to the lift pump and see what happens..[/QUOTE

I'd agree with that; good advice, take it.

I have to say that you were given the same advice in Part 1, by me and several others.

If I understand your last post correctly you are going to connect up your possibly suspect fuel supply in the tank, via a 12 volt pump, bypassing the filters, to the injector pump. I suggest that this is not a sensible move. I fully agree with your misgivings about the CAV filters but suggest you buy the spin-on substitute ones from ASAP and run your test fuel supply through one of them.

 

[Graham_Wright]

My similar problem came down to air ingress. Diagnosis was the solution. My previous post relates to installing a Tee on the outlet of the final filter with a transparent cylinder pointing upwards off the Tee and capped at the top. As an aid it has been brilliant. Each time, after a period of non running, when I look at the cylinder, it is empty. Running the fuel pump (an electric one on top of the tank) the cylinder fills, the air is expelled and the engine starts and runs sweetly. I still have to find the leak but at least I know it is upstream from the filter and I can move the Tee progressively down the fuel line until the leak is found. I guess a piece of transparent pipe would do the same thing but I don't like plastic hoses in the fuel line.

 

[Jim@sea]

If I understand your last post correctly you are going to connect up your possibly suspect fuel supply in the tank, via a 12 volt pump, bypassing the filters.
(not any more after reading the previous warnings)
I fully agree with your misgivings about the CAV filters but suggest you buy the spin-on substitute ones from ASAP and run your test fuel supply through one of them.

I need to go back to basics. The only reason I have not had the tanks out for cleaning and inspection is that they are in a really awkward place.
Just emptying the tanks and seeing if any **** comes out is probably not good enough. I have had large inspection hatches cut into the sides of the wheelhouse so one can actually get two hands in to grab the fuel filler hose although I suppose a boatyard would just hacksaw through it.

While I am waiting for the boatyard to take the tanks out. The first thing I am going to do is empty the diesel tank (again) with the 12v pump send 5 gallons of fresh diesel backwards through the pipework to perhaps clear, or dislodge any **** which might be blocking the pipework in the tank then empty it running it through a spare filter and seeing if any debris has been collected.
( But at some time the tanks will have to come out for internal inspection and cleaning, if I was setting off on a long sea journey I would have to do it for peace of mind the tanks are in a really awkward place and I am going to have the boatyard do it)
Then with the new 12v pump connected to a fresh supply, bypassing the mechanical lift pump and primary filter connect to the main filter and start the engine.
As I said I can run the engine for over an hour, yesterday I ran it for about an hour at around 2000 revs, the moment I throttled back, to tick over, it stopped. Whereas the day before it ran for about an hour and a half, at tick over, and the moment I throttled up, it stopped.

 

[Jim@sea]

Some had a gauze in the inlet banjo at the fuel injection pump, worth checking.
If you are to use a electric feed pump to test, I would make sure it is low presure (2-4psi) otherwise leek off May not cope and you could overwhelm the injection pump seal and end up with deisel in the sump.

I may have to get a mechanic to lift the engine up out of the engine bay as there is no room to get a spanner on the inlet banjo on the pump.
Mind you if I do that I can get a 1/4" shim made which will extend the propshaft further out through the hull so there is room to fit a rope cutter)
And if I can get the pump off I will send it off for a service.

 

[Taffy]

Hi,

In my case I found that the air bleed screw on the diesel filter housing had been opened and tightened so many times that the thread was worn and let in air. It was only apparent after a longer time of running. I put some PTFE tape on the screw thread and made it air tight - problem fixed. I will replace the whole fiilter housing as a long term repair.

Just an idea before you go ripping bigger systems apart.