Diesel bleeding -volvo 2030-can't get fuel to come through to the glass filter bowl ?

PaulR

PaulR

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bought a secondhand boat last winter with a volvo 2030 - had noticed that engine revs sometimes fluctuate slightly when on constant throttle setting (slightly unsettling) and saturday evening when increasing revs from 2000rpm cruise it initially responded then faltered and revs fluctuated but when throttled back to 2000 rpm cruise continued to run smoothly- fuel in glass bowl looked fine but we decided prudent to change that first filter and the fine filter on the engine too.

Changed both filters today (having switched fuel off at tank first), no visible problems with drained fuel or any visual residue in the bowl- then fuel back on and went to bleed using lift pump manual pump to pull fuel through- or so we intended - no fuel pulling through (glass bowl remained dry) but fuel flowed back from bleed screw on fine filter housing (not sure why?)

Tried rotating engine in case pump not in best cam position - no fuel pulling through.

Tried using dinghy foot pump to pressurise fuel tank through filler- no fuel pulling through.

In the end gave up and came home - have had a look online (of course) and be grateful for any suggestions.

My theory is that the engine fluctuation most likely a symptom of a restriction in fuel flow - hence my changing filters - have read of sadlers with plastic fuel tanks (as ours has) having a filter hidden away in the pick up pipe in the tank and that crudding up over the years and causing this type of problem (wish we hadn't filled tank to the brim a few weeks ago now!) so might have to try that this weekend - also read of people using outboard type squeezy bulb pumps to pull fuel through the system ,

any good ideas please?

thanks
 
I had similarish symptoms last year with a Yanmar. I was lazy though and used the fuel in the secondary filter to run the engine long enough to get fuel through into the primary filter after changing it. I can top up the secondary each time if I remove it. Don't try this technique if you aren't connected to shorepower.

Anyway, suspicion eventually fell on the copper pipes. I'd been using a lot of white diesel, and the old wives tale that bio-diesel turns to a form of jelly in contact with copper seems to be quite plausible. I used snake oil (Fuel Set and some Marine 16 Complete) which seems to have solved the problem (for now). I also fitted a vacuum gauge between the primary filter and the lift pump (as documented in another thread a week or so ago) which gives a great improvement in monitoring what's going on.
 
Like lpdsn I always change the primary filter first and then run the engine to pull through fuel to fill the glass bowl using what's left in the system. To pull fuel all the way through from the tank could in my experience with a 2030 take a very very long time.

I would be tempted to close all the bleed screws and spin the motor to see if that will draw through the fuel to the glass bowl.
 
The reassembly of the primary filter is critical. It's very easy to not quite seat the components properly, leaving a tiny air leak which will mean you cannot prime the system using the lift pump hand lever. Check the primary filter, ensuring its properly back together and try again.

priming the system with the lift pump takes forever. I fitted a squeeze bulb, like you find on outboard fuel pipesto our 2030. Makes bleeding the system a 30 second job and it's easy to spot if there's a problem with the primary filter.
 
If you have (or have access to) a Pela oil changer they can be very useful for dragging fuel through to obstinate filters, obviously not a cure for blockages also they will overcome minor air leaks and still pull fuel through so any leaks would still be present.
 
I have the outboard type bellows you mention, Mine is for diesel.
Pulls the fuel through in seconds. Much better than spinning with the starter as this could damage the starter if run too much
As well as the fuel in pipe the fuel byepass on the injectors has to be free when running otherwise engine revs will suffer
However, this should not stop you filling the filter.
Your problem is most likely tank crud
 
I have fitted a small solid state electric pump immediately after the primary filter, which is in a different compartment to the engine and the secondary filter. When it's time to bleed the system, just turn it on and then open the various bleed screws (normally just on the secondary filter) until all the air is out of the system. It makes bleeding a quick and painless process. The rest of the time the pump is left switched off, but it could be used as a backup to the lift pump if necessary.

Neil
 
I had great difficulty bleeding the fuel on my 2030 after changing both filters. Firstly as others have said, check that there is no air getting drawn into the filter assembly as it can be tricky to get the O rings correctly seated. When priming the lift pump on the engine for a minute I could hear the pressurised air going back into the diesel tank (had to listen very carefully to hear it and realise what it was). There was a bit of a technique to it and once mastered it only took a matter of seconds to bleed the whole system through. With all bleed screws closed I primed the lift pump around 4-5 full strokes and then opened the bleed screw next to the lift pump for a second or so and you should hear a loud hiss of air escaping. Close the bleed screw and repeat another 4-5 strokes (or maybe a few more depending on your fuel line run, establish how many strokes it takes before you hear the pressure going back to the tank). After each period of strokes make sure you open the engine bleed screw for a second or so to allow the air to escape. I think it took around 20 strokes in total and 4 opening/closing of the bleed screw before diesel ran through the bleed screw clearly with no air.
 
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