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Jul 31, 2023

‘Strange sticky fuel gummed up my engine’

When Andy Reeves’s otherwise highly reliable engine refused to start, approaching bad weather meant they had to set sail anyway. But solving the riddle about the cause was a harder challenge Having a

When Andy Reeves’s otherwise highly reliable engine refused to start, approaching bad weather meant they had to set sail anyway. But solving the riddle about the cause was a harder challenge

Having a breakdown at sea, and especially in the Bristol Channel, would be extremely scary, with very strong tides, navigational hazards and shipping movements, but we were suddenly confronted with a serious, and uncommon problem.

Jiggers, our 43ft Bruce Roberts Mauritius, is ketch rigged and built in steel, with two 500-litre steel fuel tanks built into the hull. The fuel has always been clean, clear and there’s never been any sludge or bug in the filters. I’ve added bug treatment for preventative maintenance, according to the instructions. Our diesel engine is a Volvo Penta MD22 60hp and we have never had an issue with it. It has always been regularly serviced and doesn’t miss a beat, starting first time every time. I’m pretty certain the fuel we took on board was clean, as our berth at the yacht club has its own fuel pump and nobody else has reported this fuel issue at the club.

We try only to use the engine when really necessary, but we use the engine quite often to help speed things up, and the diesel also gets used by a small generator and a Webasto water boiler for heating and hot water – we get through more diesel this way than for propulsion.

We sail quite often and average around 500 miles a year. In summer 2022 we sailed 841 miles from Cardiff to Guernsey, Jersey, St Malo along the French coast bays, up the River Rance and enjoying Île-de-Bréhat, then clearing customs at Roscoff. We headed back to the UK, stopping at the Isles of Scilly before heading home.

Andy and Lindsay Reeves bought Jiggers 13 years ago

It was on this trip we noticed the engine needed a little bit of throttle to start, but was fine other than that. I planned to do a good service when we got home.

We dropped the anchor at Porthcressa in the Scillies and relaxed for a couple of days on the main island, but when we went to explore further, the engine stalled immediately and wouldn’t start again. We weren’t exactly somewhere convenient, and bad weather was on its way. What were we going to do?

I ran the usual checks: battery voltage – all good; fuel at the injection pump? Yes. It could be a compression issue. Although nervous about navigating our way out of the Scillies without an engine, we decided to sail off our anchor and head straight for home, where we could investigate the issue at our leisure.

A light following breeze was due to build and push us all the way back to Cardiff. With sails set, we lifted the anchor only to find it was stuck down hard and the winch was struggling to lift it. After some extremely hard manual winching the anchor slowly appeared along with a very large, thick, heavy old armoured cable. We managed to work out a way of untangling it, eagerly watched by an audience of onlookers, none of whom offered any assistance.

The injector pump was coated in a sticky yellow substance and fuel wasn’t getting into the engine

While the 166-mile passage back to Cardiff passed without incident, crossing the TSS north of the Scillies without an engine in light winds isn’t an experience any of us would want to repeat. Nor was the prospect of a lee shore on the north Cornish coast very appealing, so we stayed well offshore. We got past Lundy and Ilfracombe in good morning light. The wind picked up and we really gained some speed against the tide in lumpy, wet, wind-over-tide conditions. We passed the Nash lighthouse in time for the evening tide.

Sheltered from the swell in Penarth Bay, we launched our 3.4m RIB off the davits and lowered the 18hp outboard onto it. With the RIB lashed alongside as far aft as possible, our eldest son Jimmy manned the engine, while I helmed Jiggers, and Rory, our youngest son, relayed messages between the two of us.

Lindsay and our daughter Claudia rigged lines and fenders ready for the lock. Barrage control kindly held the lock open for us so we could motor straight in, having lined ourselves up and dodged the low-tide mudbanks. Nervously we made it in through the narrow entrance, with just a little 18hp motor pushing our 43ft, 18-tonne yacht.

Within a few minutes we made it back to the club and were greeted by a few friends back on our pontoon. We quickly got the drinks out and celebrated an amazing family effort, toasting our lovely family boat that got us safely home.

Jiggers is a 43ft cutter-rigged ketch, built in steel to a Bruce Roberts Mauritius design

I initially thought the engine was a compression issue, so I enlisted a friend to help and started to remove the head. We noticed the timing marks didn’t line up on the injection pump pulley andit had slipped a couple of teeth. We removed the head and sent it off to be checked – a valve had bent slightly and required changing.

The polished, repaired cylinder head was returned. All was fitted back, complete with a new water pump, timing belt and idle bearings. The timing marks were set back to the correct position. I turned the ignition, but the engine just wouldn’t fire. The injection pump was working fine, but no fuel was coming out of the injectors. We took the injection pump and injectors to a local specialist to check. They said the pump had seized solid – the governor fulcrum had bent and there was a crack in the shaft of the pump.

The engineer said the pump had a yellow sticky substance internally throughout, which was very difficult to remove but when heated, it seemed to wipe away. Solvent carburettor cleaner and ultrasonic cleaning wouldn’t remove it effectively. Parts for the Volvo Penta MD22 are now becoming hard to find, and the engineers struggled to source certain parts. The issue was now taking more time to resolve.

The anchor came to the surface slowly, snagged on a heavy cable

Our engineer had recently dealt with a narrowboat with the same issue. The owner had been advised to remove and dispose of his fuel before cleaning the tank, as polishing was unlikely to remove the contamination. He had tried to polish it, however, and soon returned with a faulty fuel pump.

Investigating ‘sticky diesel’ on the internet, one article suggested it related to the possible use of fuel treatment additives where boaters on the canal network have been having the same issues. For now, this offers the best explanation.

I instructed my insurance after realising that the injection pump was faulty as I knew this was going to be a costly expense, on top of what had already been spent so far and the prospect of diesel disposal to deal with too. The insurance company was great and instructed a marine surveyor to attend, although he was less than happy that his investigations had been hampered by the work already conducted. I pointed out that we hadn’t planned to claim when we started.

The fuel level sender was also coated in a yellow film substance

On inspection the surveyor said he suspected the tank was painted with a tar-type epoxy, because the tank top had been painted with it, so tar epoxy leaching was suspected. He took a sample of fuel and some gummed-up parts from the fuel filter casing and a redundant part off the injection pump, which I collected from the engineer.

A while later I had a message from the insurance with the surveyor’s report, but this didn’t give the full fuel diagnostic report I was expecting. The insurers advised the policy wouldn’t cover the 800 litres of contaminated fuel as this is classed as consumable, however, they would pay for a new unit. This covered the cost of a reconditioned injection pump.

I pumped out all of the contaminated fuel from one of the tanks and cut extra hatches to gain better access to clean the tanks, which involved lifting the saloon teak floor and cutting hatches in the ply floor below.

The bottom of the tank was covered in a thick black rubbery goo. The tank sides were in remarkably good condition once cleaned, with no signs of paint other than a red oxide base coat which was applied in-build back in 1989, and there was no rust. The goo was not diesel bug, which is very different. I read it could possibly be Asphaltenes, which are formed during the refining process and are around 2 microns, but it clings to other particles and forms a layer over time when the fuel is heated or warm.

New hatches had to be cut to fully clean out the tanks

Whatever it was, I found the best way to remove it was scraping away the bulk and then washing with hot soapy water and a pressure washer. The diesel smelled oddly like paintbrush cleaner or turps.

I noticed bits of nitrile gasket in the bottom of the tank, which felt slippery and slimy to touch, but there was no leaking of the hatch seal. I really didn’t want this issue to happen again, but without knowing the cause, it wasn’t easy to prevent it. Could it have been old diesel? Asphaltenes build-up? Bug treatment? Rubber fuel lines or the tank gasket dissolving? Or even contaminated fuel or the way fuel is now blended with bio-fuel?

We’ve all been told that new fuel now contains elements which can possibly affect engine component seals, but the injection engineer said the pump was perfect other than being gummed-up – the seals were still very good and would have lasted a long time.

The fuel tank was free of rust and diesel bug, but was coated in a yellow goo

I researched fuel blends and found that the bio diesel and ethanol now in our fuel attacks fuel lines, and that nitrile is no longer suitable for diesel tanks, though a brand called Viton is (at three times the price), and is recommended as an inspection hatch gasket.

I was now very cautious about the fuel pipes, and changed all the hoses, including the fuel return, breather and filler pipes.

I have since got the engine up and running, this has taken over six months, missing lots of cruising time and I am seriously out of pocket too! I still have 500 litres of contaminated fuel in the port tank, which has been isolated and sealed off. I will need to dispose of this at great cost and the tank will need the same rectification work.

This problem, whatever it is, urgently needs to be addressed. Fuel companies are adding what they like to fuel, which is damaging our tanks, fuel lines and engines. Diesel was perfect before. It is extremely costly for boat owners, and could potentially have a devastating impact on safety if an engine fails at the worst possible time.

Finally refitted – the reconditioned injector pump

Filter checks – When changing filters look for a yellow honey-coloured staining inside the housing. This could be the first sign of the dreaded ‘sticky diesel’.

Fuel treatments – Fuel treatment additives shouldn’t be used as a preventative as they may react with additives already in the fuel. Instead, polish the fuel with a DIY filtration system to remove suspended water, which causes diesel bug. A simple Racor-type filter and a 12V circulation pump constantly running when rolling in the sea will help clean and remove water.

Fuel hoses – Ensure fuel pipes are ISO rated and up-to-date. They need periodic replacement too. Use Viton or equivalent as a tank gasket, not nitrile.

Storage – Modern diesel does not keep as long as it used to. Being in the damp environment of a boat doesn’t suit fuel either, where atmospheric moisture and condensation can encourage fuel bug growth. Having spare tanks means you can remove as much as possible from one tank before refilling, rather than always topping up and diluting old fuel.

Insurance – Engine problems beyond ‘wear and tear’ may be covered by your insurance. They will want to be involved from the start, however, so check with them before beginning your own investigations.

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