Indicators of clogged fuel filter

Sundance · May 06, 2007, 04:15:50 PM

I put my boat in the water this weekend and was going to transport it about 12 miles back to the marina, with 4'-6' waves and 25k+ winds, I made it about 2 miles dead into the wind and waves before I turned back because the engine was "acting up." There was a sudden drop in rpm's and then after that with almost full throttle was only doing about 2,000 rpms, but would occasionally fluctuate back up, then back down. Eventually as I was back at dock I let the boat idle, then the rpms dipped way down and the engine stopped. It started back up after a few minutes, but the same problems persisted. The diesel in the boat is old, I suspected that the seas churned up the tank, therefore I assume it is a clogged fuel filter giving me these problems. Is this correct, or would the engine have just quit on me outright? I do not want to remove the tank for cleaning, especially since there is almost 12 gallons of fuel in it (what would I do with all this fuel?), but should I expect to keep relacing filters most of the season till I can burn through the tank? I have never replaced a fuel filter, but will read up on the other posts, but I want to make sure this is the correct diagnosis. Any help?

Jim Price · May 06, 2007, 05:55:06 PM

Very high probability it was fuel sediment stirred up by the weather and when you change out your primary filter, it will probably be clogged with micro stuff. That will be good as the filter is doing its job of catching the trash in the fuel. You may also have a clogged screen on the pickup tube in the fuel tank. You will need to check both these areas first as either one will cause fuel starvation. If you have the screen on the pickup tube, get rid of it. Let the big primary filter do the job of trapping things - much easier to clean / change than messing with the fuel pickup tube inside the tank.

Much information on fuel systems and tank cleaning on the board. You can learn more than you ever wanted to know!!!

Ron Hill · May 06, 2007, 05:58:57 PM

Jeff : You sound like the classic case of neglected maintenance. You'll need to change both the Racor and the engine filters. Then pump out the old fuel (articles written on how to do this), pull the tank and clean it or have it cleaned.
BTW, you should store the boat over winter with a FULL tank of fuel!!!!
If you don't clean the tank you can expect "more of the same". If you have a filter screen on the fuel pickup tube - remove it!
Don't know what else to tell you, but read all of the posts and mainsheet tech notes on this same topic !!

Gary · May 07, 2007, 03:50:08 AM

Jeff,

Highly recommend what has been suggested as well as...clean that tank! You will be amazed at what accumulates there. Not mentioned is to also clean the fuel pump filter. On the electric pumps there is a bottom cap that inscrews then reach up into the pump and feel for a small plastic lip and pull/unscrew the micro screen filter. Clean and reinsert.

We have pumped filtered diesel into containers and added it to our heating oil tank as a way to recycle fuel when doing a tank cleaning...it is very similar to heating oil and we have had no problems doing that. We gathed the fuel from the output side of the fuel pump. We also purchased a Racor funnel with a built in filter to use as an additional filter before adding the fuel to the heating oil tank in our home.

Sundance · May 07, 2007, 04:38:42 AM

Sounds like my suspicions were correct and based other items the PO neglected I'm sure this is no exception. Thanks for the input.

Stu Jackson · May 07, 2007, 11:07:59 AM

Jeff

Suggest you go to http://c34.org/bbs/index.php?topic=3362.0 and access the Knowledgebase. Either do a CTRL-F search on fuel, or look under the engine & maintenance headings, or both.

To be able to read the references from there that are in Tech Notes Online, you can join the C34 IA and gain access (unless you are already a member although our database didn't get a hit on your boat name - what's your hull #?).

In addition to earlier responses, don't forget the proper piping from the tank to the Racor to the electric fuel pump. As installed by the factory, it's backwards, so the screen in the fuel pump that was mentioned becomes critical, when it should not. Here's a handy reference to an earlier thread: http://c34.org/bbs/index.php?topic=2515.0

Sundance · May 14, 2007, 04:18:15 AM

I removed and cleaned my tank. What a difference. I couldn't get the fuel out of the tank by using the fuel pump, but used a section of hose and a drill pump and removed all but about 1 gallon of diesel. The hardest and most time consuming part was trying to get the hoses off the tank, they were pretty stuck on after 18 years. I figure it may have been cleaned before since I could not find the screen on the fuel pick up. All said and done it only took me about 4 hours. Totally worth it.

Gary · May 14, 2007, 12:03:16 PM

Jeff,

Great!! Glad to hear all went well. The hardest part is getting the hoses off! You're filters will come out much cleaner now...not to mention that the engine and tank will now take rough seas without a fuel failure. It is a good feeling to know what is happening in the fuel system.

Thanks for letting us know the results.

Gary