Expanding fuel tanks

[njh]

Hi all.
Is this common as i have a tank that now appears to touching a pully...long story.

[shrew]

No. I would not expect a pulley to be rubbing against anything. Did it expand or simply move?

[mmwjr]

I agree with shrew, a pulley should only touch at its mounting point and definitely not the gas tank.

[njh]

Originally Posted by mmwjr

I agree with shrew, a pulley should only touch at its mounting point and definitely not the gas tank.

Of Course, it shouldn't...it wont once again when i figure out what's happened. Glad I fitted the guard...

[mmwjr]

Originally Posted by njh

Of Course, it shouldn't...it wont once again when i figure out what's happened. Glad I fitted the guard...

Never heard of this happening before. Is this a plastic or metal tank?

[Phillbo]

What pully are we talking about?

[njh]

Hi all...
So its the "Maxum fun" thread project boat.

I fitted a v8 where a v6 was..realised the tank was going to foul the rawwater impellor/pump pulley so had to remove the stern bulkhead/end of the ski locker to slide the tank forward, clear the pully and then glass all back together. I thought secured it solidly but it appears its shifted so I have to redo. No major drama and glad it's here on the drive but really curious as to how it shifted 2 inches sternward having not made it to the water and there is a very large peice of wood as a temporary tank stay you cant see. I could not move the tank back by leverage or brute force and ignorance!
Very, Very bizarre!

There are some pictures on the link below to see what im talking about...

https://photos.app.goo.gl/H2VLhDb9Y4QyRyFF6

[mmwjr]

Engine mounted raw water pump? So you are using a Bravo drive? Just asking as this boat would have come with an Alpha. You may have already told us but this thread has gone on for awhile and I lost track.

[njh]

Hi...
Originally 4.3 V6, I bought a bare boat. fitted 5.0 MPi.

I have now cut out the forward bulkhead, and i shall re-site the tank and put a bulkhead between the tank and engine and then replace the ski locker rear bulkhead.

I'm not weak but i could not shift the tank last night so i can only think that I have "walked" the tank sternwards working in the boat...

[mmwjr]

Originally Posted by njh

Hi...
Originally 4.3 V6, I bought a bare boat. fitted 5.0 MPi.

I have now cut out the forward bulkhead, and i shall re-site the tank and put a bulkhead between the tank and engine and then replace the ski locker rear bulkhead.

I'm not weak but i could not shift the tank last night so i can only think that I have "walked" the tank sternwards working in the boat...

Understand but you haven’t answered my question as to which drive (leg) you have; Alpha or Bravo?

[jparsons121]

If you have run the engine, the vibration would walk it aft little by little.

[njh]

Hi...Alpha leg.

Nope it won't start. Taken my nice new floor out today and reseated ond secured. New bulkheads to be fitted this week.

[mmwjr]

Originally Posted by njh

Hi...Alpha leg.

Nope it won't start. Taken my nice new floor out today and reseated ond secured. New bulkheads to be fitted this week.

The Alpha has a raw water pump in its mid body and you engine has a Bravo raw water pump. This is an issue as you can’t have the two in series.

[njh]

Originally Posted by mmwjr

The Alpha has a raw water pump in its mid body and you engine has a Bravo raw water pump. This is an issue as you can’t have the two in series.

I am aware but thanks for pointing it out...

[shrew]

Originally Posted by njh

Of Course, it shouldn't...it wont once again when i figure out what's happened. Glad I fitted the guard...

No offense, but you did get the answer to the question asked. If you wanted a different answer, maybe a different question would have been in order.

[njh]

Errmmm...i think somethings gone astray here.

I'm perfectly happy with the replies so far...all very helpful. Not sure what your point is unless you missed the comma?

To clarify the fuel tank seems to have simply found it's way backwards aided and abetted by me climbing in and out as well as not being secured well enough. I am amazed how it managed to move.
On investigation Fuel Tank Growth is common amongst Motorcycles, making older tanks very difficult to refit where ethanol is used. Aprilla engineers apparently can tell how old the bike is by the gap between the headstock and the tank!

Thanks for your replies

[njh]

Another update for this thread is that I have now taken the floor out, moved the tank further foward another five inches and sealed it back in and have done a much better job of the glasswork than I origionally did as it was the first major fibreglassing I ever attempted.

There is a thought to fit a through hull water intake for this engine as pointed out I can't have both water inputs which I knew but thanks for not letting it slip by unoticed.

As a thought why won't two pumps work...one before the other?

If the leg pump was brand new and the engine pump was left to run at less than 100per cent would it not just allow fluid to be delivered and then be assited to the engine circulation pump?

Cheers, Nick.

[mmwjr]

The flow rate of the legs pump is less than that of the engine raw water pump. The engine one would be starved.