Have intermittent fuel supply issues. Changed both filters but occaisionally motor Yanmar 27hp appears to starve for fuel, vibrates violently then stops. Wish to clean tank but access appears minimal / nil. Chemical clean looks logical but worried sediment in tank will remain. Does anyone know if tank has baffles which may restrict full access. Cuttting access size hole in top of tank is last resort I'd like to contemplate. Appreciate any assistance.
2004 Hunter Fuel Tank
- Thread starter lbd
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I'd start with the pick-up tube. Pull it to make sure the screen isn't clogged. Always do the easy stuff first.
What you describe almost certainly sounds like a fuel restriction problem. Do as Don suggests and remove the screen at the bottom of the pickup tube. If its partially clogged you've found the problem. I would find someone to do a fuel polishing of the tank. You could build your own with an electric pump and some filters. Just draining the tank will buy you some time but a good cleaning and some biocide are your best option.
Check your rubber hoses
It could also be a collapsing rubber hose on the suction side. You can check this by feeling all the hoses for softness while the engine is running. If you can easily compress the hose and stall the engine then that hose needs replaced.
Course this raises the issue what is causing the higher vacuum in the hose.
It could also be a collapsing rubber hose on the suction side. You can check this by feeling all the hoses for softness while the engine is running. If you can easily compress the hose and stall the engine then that hose needs replaced.
Course this raises the issue what is causing the higher vacuum in the hose.
Re: Check your rubber hoses
What's the tank made of? Aluminum or poly? Let me tell you about my recent experience with our 30 gal aluminum tank. After a few outings where the engine RPM would suddenly fall off, I suspected a clogged fuel pickup tube. I 'fixed' the problem by disconnecting the fuel line at the primary filter and using my dinghy air pump to blow the line out back to the tank, but I knew this was just treating the symptom and not the problem. This past winter, I removed the fuel level sending unit, pumped out the fuel, and looked inside, where I saw a half inch of yuck on the bottom of the tank. Apparantly the previous owner wasn't much for diesel fuel treatment, and the algaecide I'd been adding since I got the boat had killed everything that had accumulated and formed a sludge layer.
I took the tank out, brought it home, and pressure tested it - it passed. So I ordered an 8" access plate from Seabuilt and cut a 6" hole in my tank to install it. When I looked inside the now empty and clean tank, I discovered that the bottom of the tank was covered with deep pits, some almost deep enough to penetrate the tank completely. So off to the welder's it went to get a new bottom welded in.
Things I learned - the fuel intake dip tube was just a straight piece of PEX tubing cut at a bevel that sat just clear of the bottom. There was no screen or filter on it. I could have removed the diptube by unscrewing the fuel supply elbow at the top of the tank and pulling it straight up, but that wasn't obvious until I had the tank out and opened up.
Apparantly, there's a form of diesel bug that adheres to the tank bottom and walls in small clumps, and it apparantlly exudes some form of chemical that dissolves aluminum and causes pitting.
The final outcome is that I'm actually glad my engine RPM started falling off, because if it hadn't, my first indication of the severe pitting I had in the tank would have been when the tank perforated and drained 15 or 20 gallons of diesel fuel into the bildge, where I'm sure my bildge pump would have then pumped it over the side.
Oh, I just noticed you're from Australia, so that would mean it would be aluminium rather than aluminum, right?
What's the tank made of? Aluminum or poly? Let me tell you about my recent experience with our 30 gal aluminum tank. After a few outings where the engine RPM would suddenly fall off, I suspected a clogged fuel pickup tube. I 'fixed' the problem by disconnecting the fuel line at the primary filter and using my dinghy air pump to blow the line out back to the tank, but I knew this was just treating the symptom and not the problem. This past winter, I removed the fuel level sending unit, pumped out the fuel, and looked inside, where I saw a half inch of yuck on the bottom of the tank. Apparantly the previous owner wasn't much for diesel fuel treatment, and the algaecide I'd been adding since I got the boat had killed everything that had accumulated and formed a sludge layer.
I took the tank out, brought it home, and pressure tested it - it passed. So I ordered an 8" access plate from Seabuilt and cut a 6" hole in my tank to install it. When I looked inside the now empty and clean tank, I discovered that the bottom of the tank was covered with deep pits, some almost deep enough to penetrate the tank completely. So off to the welder's it went to get a new bottom welded in.
Things I learned - the fuel intake dip tube was just a straight piece of PEX tubing cut at a bevel that sat just clear of the bottom. There was no screen or filter on it. I could have removed the diptube by unscrewing the fuel supply elbow at the top of the tank and pulling it straight up, but that wasn't obvious until I had the tank out and opened up.
Apparantly, there's a form of diesel bug that adheres to the tank bottom and walls in small clumps, and it apparantlly exudes some form of chemical that dissolves aluminum and causes pitting.
The final outcome is that I'm actually glad my engine RPM started falling off, because if it hadn't, my first indication of the severe pitting I had in the tank would have been when the tank perforated and drained 15 or 20 gallons of diesel fuel into the bildge, where I'm sure my bildge pump would have then pumped it over the side.
Oh, I just noticed you're from Australia, so that would mean it would be aluminium rather than aluminum, right?
Same Problem
Like you I tried everything from filters to each pipe an union until I found the little gauze filter in the tank.
Here is an extract from my letter to Hunter
.
"Finally I decided to look into the tank itself. There is no way to extract the drop pipe into the tank without cutting a hole into the rear port locker. This was done and replaced with an access hatch (see picture) and the drop pipe removed. I was surprised to find a tiny gauze filter (see picture) at the bottom of the drop pipe. This filter was blocked with a small amount of sludge. I removed the gauze and the engine is now fine
I have received expert advice as follows:
If you send me a direct message I'll send you photos of the mod.
I had exactly the same problem with my 2004 H33 plus the fact that it happened just after starting the motor to go over the Wide Bay Bar and as a result had to get a $600 tow into Tin Can Bay.
Like you I tried everything from filters to each pipe an union until I found the little gauze filter in the tank.
Here is an extract from my letter to Hunter
.
"Finally I decided to look into the tank itself. There is no way to extract the drop pipe into the tank without cutting a hole into the rear port locker. This was done and replaced with an access hatch (see picture) and the drop pipe removed. I was surprised to find a tiny gauze filter (see picture) at the bottom of the drop pipe. This filter was blocked with a small amount of sludge. I removed the gauze and the engine is now fine
I have received expert advice as follows:
- There should be no filter in the fuel system which is incapable of being accessed. (ie without cutting holes in the vessel)
- There should be no filter which is not described in the operational manual
- There is no reason for this filter to exist as the purpose of the primary filter, (as fitted in the engine compartment on the H33) should to be exactly that, “a primary filter" not a secondary one"
If you send me a direct message I'll send you photos of the mod.
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