Fuel level question-need your thoughts

mytrojan · Post by **mytrojan** » Mon Aug 31, 2009 10:28 am

I have noticed (about a month now) that I seem to be burning fuel quicker in my port engine than in my starboard engine. I though at first I may have been running the throttle higher on the port. But it definitely seems I am burning fuel quicker in the port. The starboard level stays the same. I don't think it was just balancing between tanks- it doesn't seem to go from starboard to port (as the port level goes down- I can run 1/2+ on starboard and 1/4 on port). I do not smell gas nor do I see any discharge from the cooling water. In fact the engines are running great. Just wondering if anyone has an idea on this and what I should check.

FYI-Two years ago I replaced the fuel pump on the starboard engine when it started running rough. also- Every fall I change the gas filters. Not using E10 at this time.

fpawn1 · Post by **fpawn1** » Mon Aug 31, 2009 10:45 am

do you have the valve open --mine is located at the water/fuel filters--that the engines are using both tanks instead of each engine only using its own tank.

FDG

jddens · Post by **jddens** » Mon Aug 31, 2009 11:11 am

I have my F30 set up so each engine draws from it's own tank......and my Starboard engine uses more fuel than my port engine. About 10% more. I haven't bothered to check into it because it's not causing me any issues. I always start looking for gas a about 1/2 tank and top off.

k9th · Post by **k9th** » Mon Aug 31, 2009 11:27 am

I suspect that your crossover valve is open. I had the exact same thing happen when I first purchased my boat and was making my maiden voyage back to its new home port. When I closed it the real problem was truly identified.

I found that the reason it was open in the first place is that the former owner opened it instead of making sure the fuel delivery system was clean and functioning properly. Shortly after closing the valve the one engine started acting as if it were starved for fuel. I cleaned the anti-siphon valve and the entire system, replaced the fuel filters, and the problem went away.

According to what I have read, there should always be one valve closed.

ready123 · Post by **ready123** » Mon Aug 31, 2009 1:34 pm

jddens wrote:I have my F30 set up so each engine draws from it's own tank......and my Starboard engine uses more fuel than my port engine. About 10% more.

Mine does that too but then the genny runs off that tank and is the cause for the extra consumption.
A recent trip with no genny use, both tanks took the same amount of fuel... so I know my engine burn is the same as it should be with both being in equal tune (same age distributors, wires and spark plugs).

prowlersfish · Post by **prowlersfish** » Mon Aug 31, 2009 9:10 pm

Its not uncommon for fuel use to be different from side to side . as no two engines are exactly the same and . also if you use the gear box to reverse the prop the drag/power loss in the gear would be different then the other gear as long as its not a big difference it is normal

How much fuel difference is there from side to side when you fill it up?

Are both tach correct ?

obeejr · Post by **obeejr** » Mon Aug 31, 2009 9:18 pm

Don't rely on the fuel gauge to conclude that port and starboard engines are burning fuel at a different rate- gauges are notoriously inaccurate.

prowlersfish · Post by **prowlersfish** » Mon Aug 31, 2009 9:21 pm

obeejr wrote:Don't rely on the fuel gauge to conclude that port and starboard engines are burning fuel at a different rate- gauges are notoriously inaccurate.

you got that right ! you can only tell by filling up

guglielmo6160 · Post by **guglielmo6160** » Tue Sep 01, 2009 6:15 am

I had very similar issues , and as alot of the guys here know, it took me a little time to finally narrow it down to a clogged pickup tube in my foward tank. but I did notice that if your crossover valve is open that may happen as well.
I resolved alot of issues using electric pumps, and cleanning up all the fuel lines etc. Alot will disagree with electric pumps, but if done correctly they work great, no more priming issues, etc, and very easy replacement if there is an on water failure of the pump in the future.
but check those pickup tubes if you have original tanks

prowlersfish · Post by **prowlersfish** » Tue Sep 01, 2009 6:23 am

as long as they are marine pumps (CG aproved) and installed to CG spec elc fuel pumps are fine .

mytrojan · Post by **mytrojan** » Tue Sep 01, 2009 2:24 pm

Prowerfish paul- I noticed this variance over the last 2 months. Have not touched valves etc. I'm thinking something may be clogged. Again (knock on wood) no issues, but it has me a bit nervous. Last weekend I put 40 gal in the port and have not touched the starboard. Now they read the same 3/4- and I am seeing how many hours of running until apx 1/4 difference.

prowlersfish · Post by **prowlersfish** » Tue Sep 01, 2009 4:40 pm

Unless you fill both tanks you can't tell what you burned ,forget the gage

mytrojan · Post by **mytrojan** » Wed Sep 02, 2009 8:47 am

One question: if the cross over valve is open why would fuel transfer one way? wouldn't it tend to equalize to the same level in both tanks? why would one tank level be dropping and the other stay the same?

k9th · Post by **k9th** » Wed Sep 02, 2009 9:21 am

Because fluid will always take the path of least resistance and there will hardly ever be equal resistance in two separate fuel paths - at least that is my experience.