3988 actual fuel capacity-gctid817877

[scubadiver#3988]

I drove the boat from Morro Bay, Ca to Monterey, Ca. According to the GPS 116 miles. This is the 3rd trip taken of some distance. The most I have filled either tank is 96.3 gallons. Last trip the port tank accepted 96.3 and the starboard 90.8 (gen runs off port). I am beginning to question the capacity of the 3988 tanks or my gauges. After each trip the gauges read below E.

Bayliner lists 150 gallons per tank. I measured the port tank (56L x 31h x 16w) and calculated 124 gallons. Either Bayliner is wrong or my fuel senders are wrong.

Has anyone ever filled the tanks of a 3988 with more than 124 gallons?

Before my next fill up, I was considering pumping the balance of one tank to the other. Is this a wise decision? or am I asking for trouble?

It would let me know actually how much the tank holds.

[smitty477]

On top of each tank is a tag about 2" by 3" that tells you the volume, dimensions and tank thickness.

Sometimes it is difficult to access this tag so maybe you can use a cell phone to take a picture to read it.

The gages read a resistance value off of a variable resistor mounted at the attachment of two arms that for a "V" when they are working to show depth/volume.

Often they are 'set' off incorrectly and show less volume than exists - this is safer that the other way around. Also they tend to wear and not read too well or 'skip' from 1/4 or so to empty when they get old and well used.

When installing a new gage you can 'set' the new sender so that it reads whatever you want at mid height or at low height but be careful you know what you are setting it for as you do not want to run out of fuel.

I set them based upon depth before they get 'wet' with fuel so that they read 'empty' with about 1/8th tank left - my choice only not necessarily the best one for you.

[smitty477]

BTW- I am not familiar with the 3988 tanks but many of the other Bayliners have tanks that are not a rectangle.

So one side or more may have a deeper end than you have access to or have the ability to measure.

[smitty477]

" I measured the port tank (56L x 31h x 16w) and calculated 124 gallons. Either Bayliner is wrong or my fuel senders are wrong.

Has anyone ever filled the tanks of a 3988 with more than 124 gallons?"

Again FYI only - When I figure these dimensions I get 120 gallons.

56 X 31 x 16 / 231 = 120 gallons

[The_Other_Gary]

I had a fuel truck in last week. my gauges showed 10% port and 15% starboard.

I took 222 gallons and only filled to 90% to avoid spillage.

I have the accu-gage system and recently removed the probes to set the empty reading then filled to set the full reading.

Seems pretty much correct as 77.5 % of 298 gal is 230 gal.

[Uncle_Bob]

"gen runs off port" are you sure? Mine runs off stbd. You can check the old fashioned way and pull the sender and use a yardstick to see how deep the tank is and how much fuel is there. Then compare to the gauge.

[The_Other_Gary]

The manifold under the center deck hatch in the salon allows switching any tank to any engine including the genny. and also allows redirecting the return lines.

Measuring the fuel sender travel against the known depth of the tank is also a good idea.

[Uncle_Bob]

My 2001 doesn't have the manifold but does have shut-offs and a fuel transfer pump.

[The_Other_Gary]

"Uncle Bob" post=817913 wrote:
My 2001 doesn't have the manifold but does have shut-offs and a fuel transfer pump.

That's too bad that they deleted the manifold for your model year.

In my opinion it is the best for fuel management, ballast management and by adjusting the return line settings you have three engines that can transfer fuel instead of relying on a single pump that will let you down right when you need it.

[kev_rm]

ok sorry you are basing your estimate of capacity off the gauges? Use a stick

[Uncle_Bob]

I don't miss the manifold. Had 'em, never used. Do use the transfer pump. BTW, I witnessed the results of a manifold switched to both engines to one tank last week. Skipper forgot and filled the club with diesel through the vent. Lucky he wasn't caught for a big fine.

[Grafty]

I owned a 3988 for over two years and never found the gauges to be accurate or to be dependably inaccurate. Knowing how much fuel I have is a big deal. I ended up using a fuel stick calibrated for each tank. The 3988 has good access to add a port in the top of the tank to drop a calibrated stick into the tank from inside the salon. At the rear end of each tank there is a sending unit location. I removed the sending units and drilled a hole next to the sending unit access hole large enough to put in a fitting (AN bulkhead fitting) that had a backing nut inside the tank and a removable cap. I was able to use about a 3/8" wooden dowel rod with graduated markings. Access to this area is thru the carpeted small hatch on the starboard side and a corresponding hatch under the couch on the port side. I found that 1" on the stick represented almost exactly 5 gallons. After some experimentation under actual filling conditions, I was able to predict the amount of fuel I took on to within 5 gallons using the sticks. Poor mans flow scans

[Uncle_Bob]

Thanks are labeled 148 gal each.