Rusted fuel filter

[77_starcraft]

1998 7.4mpi/bravo

I install a new fuel filter at the end of every season as part of yearly maintenance. This time there was no water in the filter but visible rust on both sides of the filter (inlet and outlet). I had checked the filter earlier this year in July and it had a very small amount of water, less than 1 oz. I use merc filters.

I cannot understand how the filter rusted, especially all the way at the very top of the element. Water in Ethanol fuel? Shouldn't the water seperating filter prevent this? I have used stabil marine ethanol treatment on every fill up.

I had run the engine on muffs to warm up the oil before changing it, and it runs fine. I installed a new fuel filter and purged the system through the test port, pumped a 1/2 gallon clear contain full of fuel 2 times. I removed the new fuel filter and checked for water, it had none. I know that the system has been contaminated with rust and that the regulator and injectors may clog at some point.

Please advise on how this may have happend, how to prevent again, and some options to flush, test or inspect. Thanks

 

[smokeonthewater]

Re: Rusted fuel filter

maybe it was rusted before installing.... I have pulled brand new oil filter out of the box and found rust in them before

 

[Chris1956]

Re: Rusted fuel filter

Mercruiser oil filters would occasionally rust thru. Obviously the rust came from outside.

 

[Bondo]

Re: Rusted fuel filter

I had checked the filter earlier this year in July and it had a very small amount of water, less than 1 oz. I use merc filters.

Ayuh,.... Did ya put the same filter back on,..??

The filters separate water by gravity,...
It's still good technology, but not 100%,...

Best as I can understand yer rust factor, I'm guessin' condensation durin' times of inactivity is the culprit,...

The filter is on the vacuum side of the fuel pump, 'n a tiny bit of headspace in the filter is not unheard of,...
Any air space can form condensation, 'n any steel in that space is where rust would form,...

 

[77_starcraft]

Re: Rusted fuel filter

The rusted filter was rust free when it was installed a year ago. It had no rust when I inspected in July, and yes I re-installed the same filter back then.

The filter has small rust deposit clumps evenly distributed throughout the visible area of the filter, on both sides of the filter media. Seems like it would have to be completely empty for this to happen. Perhaps I forgot to purge the air out after I emptied it.

 

[dingbat]

Re: Rusted fuel filter

First, understand that raw fuels is dumped on the bottom, unside the filter then "sucked" thru the filter and out the top of the filter. A10 um filter would have removed any particles big enough to be of concern.

You need oxygen, not "air" to generate rust so I don't understand the concern of bleeding the air out of the filter. Filter by nature are self bleeding by operating on the vacuum side of the system.

Are you sure it's rust? Brown Algae and mold are known to grow in fuel. If indeed rust, the accumulation will stick to a magnet

 

[77_starcraft]

Re: Rusted fuel filter

First, understand that raw fuels is dumped on the bottom, unside the filter then "sucked" thru the filter and out the top of the filter. A10 um filter would have removed any particles big enough to be of concern.

You need oxygen, not "air" to generate rust so I don't understand the concern of bleeding the air out of the filter. Filter by nature are self bleeding by operating on the vacuum side of the system.

Are you sure it's rust? Brown Algae and mold are known to grow in fuel. If indeed rust, the accumulation will stick to a magnet

It's definitely rust. What I think happened is I emptied the filter, screwed it back on and forgot to cycle the key a few times to displace the air with fuel. It must have sat full of air long enough to rust before the boat was used again. rust has developed on the outlet side of the filter, and the threaded tube of the filter housing. The first jug of fuel I pumped out of the system had rust particles in it. not good.

 

[GA_Boater]

Re: Rusted fuel filter

Maybe the filter is doing it's job? Is your tank clean? Got any pics?

 

[77_starcraft]

Re: Rusted fuel filter

When I bought the boat 4 years ago the tank had a good quart or 2 of water in it. I ended up pulling the floor and sending unit to remove all the fuel and water. The tank was clean and in good shape.

 

[Fleetwin]

Re: Rusted fuel filter

When I bought the boat 4 years ago the tank had a good quart or 2 of water in it. I ended up pulling the floor and sending unit to remove all the fuel and water. The tank was clean and in good shape.

Four years is a long time and a lot fuel has gone through there since.

Be thankful you had a filter on there at all.

 

[Fun Times]

Re: Rusted fuel filter

Rust has developed on the outlet side of the filter, and the threaded tube of the filter housing.

Truthfully it's not all that unusual to find some surface rust on the top side of a Mercruiser fuel filter when you remove it from the filter base. I've personally seen many filters with a little bit of what I'd call surface rust on it without having any signs of water in the fuel when emptied to check it's contents.

For me, The important thing to know is the condition of the fuel inside the filter as I don't rely on the filter surface rust as a sign of big problems anymore.