MarcelSydney
Seaman
- Joined
- Jul 5, 2021
- Messages
- 53
Hi from Sydney, Australia. Been reading your site a lot as I have just bought which wasn't meant to be a project but has become one. Hoping someone may be able to help me solve.
It is a 1999 Maxum 1800 with a 4.3L V6 Mercruiser. 2 Barrel Mercarb. Serial numbers are OL323311 (engine) and OL509362 (Transom).
Short story:/
1. Man buys boat, looks good. Convinces wife its a great idea and all the work has been done already!
2. Boat runs great for 2 trips. Wife comes around!
3. Man has engine serviced by mechanic. Work on it together. Discover fuel filter is filthy. Full service, oils changed, impellor, sparks etc etc.. Man feeling good, mechanic says its great apart from a very dirty fuel filter.
4. Next trip, boat breaks down with wife's family and kids on board in Sydney Harbour after man forgot to fill it up with fuel. Doh!
5. Get a jerry can, put 20L in, can get it started just, idles, then dies.
Get back to shore eventually, trailer home. Do the following.
1. Pull the fuel filter off. Found to have at least 2/3rd's water and general rubbish probably from bottom of tank.
2. Drain the tank, water in the tank probably 3-4 litres. Wipe tank clean, not too bad. Put on new filter, and a second water separating filter. Fill tank up with 98 octane and a heap of fuel stabiliser. Motor runs, but still same problem.
3. Pull carburettor off, generally pretty filthy. Clean it up and with with new quicksilver carburettor rebuild kit.
4. Painted it, put it on the motor and boat purrrrsss. Take it out for a blast for 40mins. Beautiful. Idles like a champ, easy to dock and get on trailer (i.e smooth acceleration), and top end it roars.
Then on the second trip, it starts hesitating after idle, like it wants to stall. If i rev it up a bit, it'll go, but it is annoying. Progressively gets worse. Still runs well once going and WOT.
So my thoughts are from other threads that maybe accelerator pump or something else??? i don't know. I only know enough mechanical stuff to get out of trouble. Carby tuning seems like a dark art to me and getting it right takes a lot of experience so I reckon I have messed something up. I pulled the spark plugs to have a look if lean or rich. From other sites, i was expecting a lean looking plug, but i think this is a sign of rich (see attached pic)??
The one thing in the back of my mind is that when I put i back together (i left the carby in pieces and sitting for a couple of days before reassembling due to work and painting it). I noticed that the the springy thing (Vacuum Piston i believe) was jammed (it wasn't when pulled apart). I couldn't get this part out when cleaning and the video i watched told me not to in case i damaged it.
So i sprayed it with a bit of oil to try and free it up, it was jammed tight. It eventually worked loose.
From what i read, that seems quite an important part when coming off idle and accelerating so im wondering if i need to pull the carby apart again and try and get that part out and clean it? Its the only thing i can think of.
Any other ideas or help would be appreciated. I just can't figure out why it would work so well, and then not.
Thanks in advance.
marcel.
It is a 1999 Maxum 1800 with a 4.3L V6 Mercruiser. 2 Barrel Mercarb. Serial numbers are OL323311 (engine) and OL509362 (Transom).
Short story:/
1. Man buys boat, looks good. Convinces wife its a great idea and all the work has been done already!
2. Boat runs great for 2 trips. Wife comes around!
3. Man has engine serviced by mechanic. Work on it together. Discover fuel filter is filthy. Full service, oils changed, impellor, sparks etc etc.. Man feeling good, mechanic says its great apart from a very dirty fuel filter.
4. Next trip, boat breaks down with wife's family and kids on board in Sydney Harbour after man forgot to fill it up with fuel. Doh!
5. Get a jerry can, put 20L in, can get it started just, idles, then dies.
Get back to shore eventually, trailer home. Do the following.
1. Pull the fuel filter off. Found to have at least 2/3rd's water and general rubbish probably from bottom of tank.
2. Drain the tank, water in the tank probably 3-4 litres. Wipe tank clean, not too bad. Put on new filter, and a second water separating filter. Fill tank up with 98 octane and a heap of fuel stabiliser. Motor runs, but still same problem.
3. Pull carburettor off, generally pretty filthy. Clean it up and with with new quicksilver carburettor rebuild kit.
4. Painted it, put it on the motor and boat purrrrsss. Take it out for a blast for 40mins. Beautiful. Idles like a champ, easy to dock and get on trailer (i.e smooth acceleration), and top end it roars.
Then on the second trip, it starts hesitating after idle, like it wants to stall. If i rev it up a bit, it'll go, but it is annoying. Progressively gets worse. Still runs well once going and WOT.
So my thoughts are from other threads that maybe accelerator pump or something else??? i don't know. I only know enough mechanical stuff to get out of trouble. Carby tuning seems like a dark art to me and getting it right takes a lot of experience so I reckon I have messed something up. I pulled the spark plugs to have a look if lean or rich. From other sites, i was expecting a lean looking plug, but i think this is a sign of rich (see attached pic)??
The one thing in the back of my mind is that when I put i back together (i left the carby in pieces and sitting for a couple of days before reassembling due to work and painting it). I noticed that the the springy thing (Vacuum Piston i believe) was jammed (it wasn't when pulled apart). I couldn't get this part out when cleaning and the video i watched told me not to in case i damaged it.
So i sprayed it with a bit of oil to try and free it up, it was jammed tight. It eventually worked loose.
From what i read, that seems quite an important part when coming off idle and accelerating so im wondering if i need to pull the carby apart again and try and get that part out and clean it? Its the only thing i can think of.
Any other ideas or help would be appreciated. I just can't figure out why it would work so well, and then not.
Thanks in advance.
marcel.
