1995 4.3lx idles fine, runs out of water, dies in water

bmxnick7

Cadet
Joined
Jul 7, 2013
Messages
7
I recently purchased a new boat. its a 1995 chaparral 1830 sst. after doing some research. the motor is a 4.3 with a 4 barrel weber carb. previous owner replaced the complete long block approx 3 years ago and says it has very minimal use. boat ran fine at idle on hose. I asked for a water test he said boat was not insured or reg. so against my better judgment I purchased the boat. so on way home I put approx 15 gal of fresh gas in it. took boat out and guess what It doesn't run right big surprise. idles fine and would go to approx 2600rpm at wot. backfiring out of carb. so next day changed water/fuel separator. took out next day no change. did some snooping in water on carb and secondary's were not opening. so removed second butterflies and rod and they became free moving. installed carb back on boat. took some advice from a friend and checked timing. there was no scale attached to timing cover. there was a notch. and a line on balancer. assuming this is zero degrees. according to my gun which has an advance/retard scale on it the timing was 40deg advanced. rotated distributor to set this to 8deg advance boat seemed to run 100 times better on hose. took boat out idled out of the no wake and opened her up. ran up to approx 4300 rpm. then started to sputter. then would not except and throttle at all. unless in neutral. idled all the way back to the trailer. I am at a loss at this point. the plugs cap rotor wires are all brand new. I am kind of at a loss at thing point. I am going to be rebuilding the carb who knows what inside looks like if secondary were seized. any help is appreciated. thanks in advance
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Re: 1995 4.3lx idles fine, runs out of water, dies in water

I recently purchased a new boat. its a 1995 chaparral 1830 sst. after doing some research. the motor is a 4.3 with a 4 barrel weber carb. previous owner replaced the complete long block approx 3 years ago and says it has very minimal use. boat ran fine at idle on hose. I asked for a water test he said boat was not insured or reg. so against my better judgment I purchased the boat. so on way home I put approx 15 gal of fresh gas in it. took boat out and guess what It doesn't run right big surprise. idles fine and would go to approx 2600rpm at wot. backfiring out of carb. so next day changed water/fuel separator. took out next day no change. did some snooping in water on carb and secondary's were not opening. so removed second butterflies and rod and they became free moving. installed carb back on boat. took some advice from a friend and checked timing. there was no scale attached to timing cover. there was a notch. and a line on balancer. assuming this is zero degrees. according to my gun which has an advance/retard scale on it the timing was 40deg advanced. rotated distributor to set this to 8deg advance boat seemed to run 100 times better on hose. took boat out idled out of the no wake and opened her up. ran up to approx 4300 rpm. then started to sputter. then would not except and throttle at all. unless in neutral. idled all the way back to the trailer. I am at a loss at this point. the plugs cap rotor wires are all brand new. I am kind of at a loss at thing point. I am going to be rebuilding the carb who knows what inside looks like if secondary were seized. any help is appreciated. thanks in advance

Ayuh,.... Welcome Aboard,... It sounds like a fuel delivery issue, so rebuildin' the carb is a Good start,...

Check the contents of the fuel filter for crud, 'n water too,...
 

bmxnick7

Cadet
Joined
Jul 7, 2013
Messages
7
Re: 1995 4.3lx idles fine, runs out of water, dies in water

Ayuh,.... Welcome Aboard,... It sounds like a fuel delivery issue, so rebuildin' the carb is a Good start,...

Check the contents of the fuel filter for crud, 'n water too,...

pulled carb apart and inside is very clean. none of the passage ways seem clogged or anything like that. so that part beats me. there was also no filter in the carb itself. I emptied water/fuel separator nothing but gas in that. checked my vent to the tank that's ok. checked my anti siphon valve that's ok. I did notice when I was check fuel pressure that my oil pressure gauge was reading zero. I am pretty positive this worked before. I did read some where that no oil pressure would cause the fuel pump to not work. but would this cause it to not work at idle as well.
 

1ruralmailman

Seaman
Joined
Aug 25, 2010
Messages
59
Re: 1995 4.3lx idles fine, runs out of water, dies in water

pulled carb apart and inside is very clean. none of the passage ways seem clogged or anything like that. so that part beats me. there was also no filter in the carb itself. I emptied water/fuel separator nothing but gas in that. checked my vent to the tank that's ok. checked my anti siphon valve that's ok. I did notice when I was check fuel pressure that my oil pressure gauge was reading zero. I am pretty positive this worked before. I did read some where that no oil pressure would cause the fuel pump to not work. but would this cause it to not work at idle as well.

I believe that the oil pressure switch will cut the fuel pump if it is not working.there is a thread on testing it on here somewhere.good luck.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 1995 4.3lx idles fine, runs out of water, dies in water

If you didn't have oil pressure, the fuel pump would shut off completely. Then it wouldn't idle either. You do need to verify your oil pressure. Have you checked the oil level? If it's over full, you will have aerated oil which would cause the oil pressure to drop and the lifters to go soft causing running problems.
 

bmxnick7

Cadet
Joined
Jul 7, 2013
Messages
7
Re: 1995 4.3lx idles fine, runs out of water, dies in water

rebuilt carb. still no dice. decided to recheck my timing and now It is retarded. so I reset it to 8deg. while just watching the timing light I was able to watch the timing move. like the distributor was being moved. but it was bolted solid. so I am going to look in to the distributor tomarrow.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: 1995 4.3lx idles fine, runs out of water, dies in water

What kind of distributor and ignition system is on it?
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: 1995 4.3lx idles fine, runs out of water, dies in water

Did you follow the Merc specified procedure for timing adjustment?
 

bmxnick7

Cadet
Joined
Jul 7, 2013
Messages
7
Re: 1995 4.3lx idles fine, runs out of water, dies in water

Being thunderbolt 4 isn't it just point and shoot.
 
Top