1998 21 CONQUEST Fuel Capacity

A conversation among Whalers
hallmant
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1998 21 CONQUEST Fuel Capacity

Postby hallmant » Mon Sep 27, 2021 8:37 pm

I recently purchased a 1998 21 CONQUEST. The previous owner said the fuel capacity was 96-gallons [based on what is described only with this arithmetic] 55+41.

Recently I added fuel. I was only able to add 46-gallons. The [fuel tank level] indicator showed full.

When I look at the access port for the fuel tank, I only see one plastic tank. [A placard indicates a capacity of] 55-gallons [for that one tank].

Q1: on a 1998 21 CONQUEST Is there a valve I might be missing?

jimh
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Re: 1998 21 CONQUEST Fuel Capacity

Postby jimh » Tue Sep 28, 2021 9:01 am

When you began to add fuel to the fuel tank on your 1998 21 CONQUEST, what was your basis for assuming that when the pump cut off at 46-gallons there was something wrong?

What was your method for determining how much fuel was already in the fuel tank?

jimh
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Re: 1998 21 CONQUEST Fuel Capacity

Postby jimh » Tue Sep 28, 2021 9:17 am

I don't understand your statement of "55+41". Where does that come from?

For a 21-foot boat to have a fuel capacity of almost 100-gallons seems very unusual. However, I do see several references to the 21 CONQUEST having a fuel tank with 92-gallon capacity in some prior discussions. Here is a link to some specifications listed by Boston Whaler:

http://web.archive.org/web/199802060420 ... st.21.html

There is a similar old discussion at:

https://continuouswave.com/ubb/Forum8/HTML/002199.html

If you only see one fuel tank, and that tank has a capacity sticker that says 55-gallons, the most reasonable inference is the boat's fuel capacity is 55-gallons.

Perhaps the fuel capacity was originally 92-gallons when the boat was being sold with older two-stroke-power-cycle engines whose fuel consumption was rather high. When the boat was later sold with a modern two-stroke-direct-injection engine (like the OptiMax), perhaps Boston Whaler reduced the fuel tank capacity to 55-gallons. The basis for that would be an expectation that the modern engine would get almost double the MPG than the older engine so less fuel capacity would be needed. Also, the modern engine would weigh more, so perhaps a reduction in weight carried as fuel was deemed necessary to keep the boat in proper trim.

Mambo Minnow
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Re: 1998 21 CONQUEST Fuel Capacity

Postby Mambo Minnow » Fri Jan 14, 2022 7:18 pm

I have a 1999 Conquest 21 with an Optimax 200hp direct injection two stroke engine. The boat still came with the 92 gallon fuel tank.