Hi everyone. This may be long, but I want to give you the most info in hopes of increased chances of a better diagnosis.
Here's what I've got; 1984 SportCraft with original (1984) Merc 488r (aka 170) 3.7L with Alpha I Gen I.
Bought the boat about a month ago, and the previous owner hadn't used it in about a year +/-.
When I first got it in the water, it idled fine, but it would stall when given some throttle. At first, anything above idle would cause it to die within 30 seconds. It would also be a little tough to restart. Got her home (slowly), and the next day went and started her up. No problem starting and idling. In neutral, I could give it all the throttle I wanted without any problem. Tried taking her out on a test run, and sure enough, she would bog and die if I didn't pull back to idle quick enough. Pumping the throttle seemed to help occasionally, but it would still die.
First thing I did was visually make sure there was fuel. There was about a half a tank (40 gals.). Checked the FWS for water, and that was ok as well. I then checked the filters, and subsequently replaced the FWS filter, fuel pump filter, and the fuel filter at the carb. The carb filter was pretty much clogged. Changing the filters helped dramatically, and I was able to run it for a while (don't know how long exactly), but she would eventually bog and die.
At some point around here I also ran about 2 cans of carb cleaner through her.
Next step was condition of the fuel. I confirmed no water in the tank, and the fuel looked and smelled ok, but I went ahead and hooked up to a topside gas tank (6.5g tank, had 5 gals in it). Ran the entire 5 gallons without a hesitation, until I ran out of gas. I hooked back up to the regular tank and got back to the dock without incident. I do not recall if I stayed at around idle speed or if I opened it up after I hooked back up, as it was a fairly short distance.
With this info, I then emptied the tank, and refilled (only 1/4 tank) with non-ethanol fuel from the marina.
That brings us to yesterday. I was going to change plugs, cap, rotor, points, and condenser, but when I opened the cap, the points weren't gapped correctly, so I gapped to 0.022", and closed her back up. Wanted to see if that may have been it.
Left the dock, ran for about 2 hours, mostly at 3/4 throttle, sometimes WOT, but slow only in the minimum wake zones. Temp stayed in the proper range (140-170) (I think that's the range I want to be in), and everything sounded good. WOT rpm's should be 4400-4800, but I have a 19" prop, and I'm only getting 4100. I will be changing the prop if there aren't any other problems that could be causing the low WOT, but have to get her running first.
Anyway, about 2 hours into the run yesterday, she started to bog again, and while she didn't die as quickly after the bog as she had before, (ie, she died slowly once she bogged) she would die unless I dropped rpm's down to 1100-1400+/-.
So today I went ahead with yesterday's original plan, and changed plugs, cap, rotor, points, and condenser. Basic tune-up. I did not change the wires, as they look good. Actually, the stuff I changed looked like they didn't need to be changed, but now they are emergency spares. Plugs were tan to brown, and no unusual wear or fouling was noticed.
One thing I noticed that definitely shouldn't have been. I removed the distributor plate (I have no idea what it's really called). It's the base plate that you screw the points and condenser onto. When I did that, there was brownish/rusty water in there. Not a ton, but I know water shouldn't be there. I cleaned it out with a rag, and got the water out (mechanic at West Marine thinks it's from basic condensation/humidity).
After I put everything back together, she started right up, and purred. Sounded a little smoother then she had before. It started raining really hard just as I was spraying what was left of the 2nd can of carb cleaner from the other day through her, and I'm wondering if a couple drops of rain water got in the carb. She died about 15 minutes after the carb cleaning.
I tried to restart her, but she wouldn't go. Almost sounded like she was out of gas (there is gas). It was raining cats and dogs and this point, and after about 10 minutes of trying to restart, I gave up and went home to dry off.
So at this point, after reading about every thread on this and another forum related to this problem, I'm thinking either coil, accelerator pump(s), or fuel pump. The line that runs from the fuel pump to the carb for if/when the fuel pump diaphragm fails/leaks is aged, and I can't see if there is any fuel in it, but I don't think there is.
What is the next step? This is going to drive me crazy....
Thanks in advance for your thoughts!
Here's what I've got; 1984 SportCraft with original (1984) Merc 488r (aka 170) 3.7L with Alpha I Gen I.
Bought the boat about a month ago, and the previous owner hadn't used it in about a year +/-.
When I first got it in the water, it idled fine, but it would stall when given some throttle. At first, anything above idle would cause it to die within 30 seconds. It would also be a little tough to restart. Got her home (slowly), and the next day went and started her up. No problem starting and idling. In neutral, I could give it all the throttle I wanted without any problem. Tried taking her out on a test run, and sure enough, she would bog and die if I didn't pull back to idle quick enough. Pumping the throttle seemed to help occasionally, but it would still die.
First thing I did was visually make sure there was fuel. There was about a half a tank (40 gals.). Checked the FWS for water, and that was ok as well. I then checked the filters, and subsequently replaced the FWS filter, fuel pump filter, and the fuel filter at the carb. The carb filter was pretty much clogged. Changing the filters helped dramatically, and I was able to run it for a while (don't know how long exactly), but she would eventually bog and die.
At some point around here I also ran about 2 cans of carb cleaner through her.
Next step was condition of the fuel. I confirmed no water in the tank, and the fuel looked and smelled ok, but I went ahead and hooked up to a topside gas tank (6.5g tank, had 5 gals in it). Ran the entire 5 gallons without a hesitation, until I ran out of gas. I hooked back up to the regular tank and got back to the dock without incident. I do not recall if I stayed at around idle speed or if I opened it up after I hooked back up, as it was a fairly short distance.
With this info, I then emptied the tank, and refilled (only 1/4 tank) with non-ethanol fuel from the marina.
That brings us to yesterday. I was going to change plugs, cap, rotor, points, and condenser, but when I opened the cap, the points weren't gapped correctly, so I gapped to 0.022", and closed her back up. Wanted to see if that may have been it.
Left the dock, ran for about 2 hours, mostly at 3/4 throttle, sometimes WOT, but slow only in the minimum wake zones. Temp stayed in the proper range (140-170) (I think that's the range I want to be in), and everything sounded good. WOT rpm's should be 4400-4800, but I have a 19" prop, and I'm only getting 4100. I will be changing the prop if there aren't any other problems that could be causing the low WOT, but have to get her running first.
Anyway, about 2 hours into the run yesterday, she started to bog again, and while she didn't die as quickly after the bog as she had before, (ie, she died slowly once she bogged) she would die unless I dropped rpm's down to 1100-1400+/-.
So today I went ahead with yesterday's original plan, and changed plugs, cap, rotor, points, and condenser. Basic tune-up. I did not change the wires, as they look good. Actually, the stuff I changed looked like they didn't need to be changed, but now they are emergency spares. Plugs were tan to brown, and no unusual wear or fouling was noticed.
One thing I noticed that definitely shouldn't have been. I removed the distributor plate (I have no idea what it's really called). It's the base plate that you screw the points and condenser onto. When I did that, there was brownish/rusty water in there. Not a ton, but I know water shouldn't be there. I cleaned it out with a rag, and got the water out (mechanic at West Marine thinks it's from basic condensation/humidity).
After I put everything back together, she started right up, and purred. Sounded a little smoother then she had before. It started raining really hard just as I was spraying what was left of the 2nd can of carb cleaner from the other day through her, and I'm wondering if a couple drops of rain water got in the carb. She died about 15 minutes after the carb cleaning.
I tried to restart her, but she wouldn't go. Almost sounded like she was out of gas (there is gas). It was raining cats and dogs and this point, and after about 10 minutes of trying to restart, I gave up and went home to dry off.
So at this point, after reading about every thread on this and another forum related to this problem, I'm thinking either coil, accelerator pump(s), or fuel pump. The line that runs from the fuel pump to the carb for if/when the fuel pump diaphragm fails/leaks is aged, and I can't see if there is any fuel in it, but I don't think there is.
What is the next step? This is going to drive me crazy....
Thanks in advance for your thoughts!