Fuel Problem?

[Dom22]

I have recently bought a sealine 22 sport and have been having a few problems with my Mercruiser 3.6 Diesel.

I have been suffering from loss of power at high revs - the revs initial come up for a few seconds, then die right down until I throttle back. At low revs, the engine is fine. On changing the fuel filters, I found a thin, black liquid in the primary fuel filter. The mercruiser agent thought that it might be diesel bug, but was not sure.
With the new filters, the problem still remains the same, but the filters are now clean (i.e. no black liquid).

The problems seem to have arisen after I filled the tank up with fuel and added 'fuel doctor' as a precautionary measure (I have just bought the boat, and the dealer said using a fuel additive is sensible). Since then, the engine is smoky at start up and takes several turns of the key.

I am considering having the fuel tank cleaned by Expresslube.
Any thoughts/ideas would be gratefully received.

Dominic.

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[Freebee]

well it could be fuel bugs, but if the filters are now clean and not blocked and the problem persists, are there any inspection hatches on the tanks so that you can get a look or sample the inside, I would also think about bleeding the system again and check the whole system for loose or bad connections allowing air to be sucked in instead of fuel.

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[DavidJ]

Sounds a bit like fuel starvation. With a diesel the pump gives more than the engine needs and the excess goes back to the tank. The pump you have is probably mechanical and I believe the diaphram can become punctured.


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[Solitaire]

B4 you get fuel tank drained and cleaned, go and buy a 500ml bottle of Soltron. Loads of other forum members will swear by the stuff. I converted from petrol to diesel and had problems with residue/muck in the tank. Was told about Soltron and no problems since. Another forumite did not change his filters for 18 months and they were clean. I was also on a course last week where a guy had problems with his tank - busted weld - but engineeer said he'd not seen a cleaner tank. The guy had been using Soltron for 3 years.

Try it first!

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[tcm]

I had a silimar problem, cept it eventually stopped the engine at all revs, not just high revs.

There may be a prelimnary filter in the tank, and loads of gunk there. You could easily have clean filters if this is the setup. No harm in getting expresslube to get the stuf out, clean it put it back imho. Make sure that they get the content of the tank mixed up first, then praps add soltron to whatever goes back in.

I hear that you shd get a firm quote from expresslube in the uk first.

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[hlb]

There is a silly little filter on some V**splutter** fuel pumps, volslutter engineers just chuck them away as being less use than chocolate tea pots. For what ever reason, you have fuel starvasion. I've had it on and off all bloody year on one engine!!

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Haydn

 

[martynwhiteley]

Just another thought on the same line as fuel starvation.....

When I installed the new 1.7 Diesel in the last boat, it starved of fuel on my maiden voyage. but only at high revs.

All the system was new, and I'd even filled up with road diesel to ensure the conditions for the trail were 'perfect'.

I was at a loss and beginning to blame a fault with the new engine, until an experienced diesel mechanic I talked to said, "what size pipe did you use for the return line?" (whilst taking another puff on his pipe)

"10mm" I replied, "just like the feed, I only needed to use 8mm, but just to be sure".

"There's yer problem" he said, "the return line's too big, throttle down the valve on the return line, and it'll be alright".

Sure enough, I did what he said and it never missed another beat. Apparently if the return line is too 'large', the fuel takes the path of least resistance and starves the cylinders.



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[omega2]

You also mention smoke, what colour? and when? could be something as simple as a loose clip on the air intake side or split in rubber hose connecting same, can be a sod to find but go for the simple fixes first, it will save you money.

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[Dom22]

Thanks everyone for the responses. The smoke is grey in colour, and only at first start up. Beofre the problems, there was only a small amount of smoke at first start-up.

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