Problem;
My boat runs great for short periods of time, then bogs/ looses power, then goes back to running well (briefly).
This cycle of running good, power loss, running good again varies greatly, both run good, and wait time to run again.
Sometimes 5 min good run with 2 min wait, sometimes 30 sec good run with min wait, some times several min good run, wait time less than 30 sec. and runs good for 5 mins.
I have read as many related post to both mercury and other motors alike most all of them say fuel, in my case, I do not think its fuel.
Please read over what I have done so far, and give me any suggestions or similar problems that were solved.
Thanks in advance.
BOAT SIDE; 1990 Astro quickfire 16 F/S
1 Replaced fuel in tank.
2 Confirmed tank ventilation open.
2 Checked pickup tube.
3 Replaced fuel filter and water separator.
4 Replaced all fuel lines and clamps with 3/8" I.D.
5 Replaced primer bulb.
Motor Side; 1990 Mercury 90HP ELOPT 3cyl
Prop/motor/boat factory
Compression check WOT cyl-1 135psi, cyl-2 125psi, cyl-3 130psi checked twice. First time cyl-2 only 120psi
1 Replaced all fuel lines and clamps with 3/8" I.D.
2 Replaced fuel filter.
3 Replaced all other tubes hoses and clamps.
4 Rebuilt fuel pump 1st time OEM kit (only comes with plastic disc).
5 Rebuilt fuel pump 2nd time Sierra kit (has plastic disc and rubber valve).
6 Removed cleaned and rebuilt carbs.
7 Set floats to factory specifications.
8 While carbs were off, inspected reeds through intake manifolds.
9 Confirmed main jet and bowl vent orifice size.
10 Adjusted low speed mixture per OEM manual.
11 Timing/Synchronizing/Adjusting per OEM manual.
12 Confirmed good spark on muffs, idle.
13 Muffs @idle, ran on cyl1 only, cyl2 only,and cyl3 only (ran surprisingly well).
14 At lake When motor started to loose power, pumped bulb, was firm, no changes.
15 At lake When motor started to loose power, touched ea coil, not to hot and even.
16 Has new water pump. Also touched heads over ea cyl, not to hot and even.
After all this, It started first attempt, idled in gear @ 700 rpm perfectly.
hole shot was better than ever, WOT at 45 mph @ 5100 rpm for about 15 mins.
Suddenly looses power (as if lack of fuel) tach reads 3000 rpm, pumped primer again, no change.
move throttle from WOT to just under half rpm drop from 3000 to 2900, Seems to be powered correctly for that rpm range.
hold their for a min or two (to get out of the way) drop to neutral, idles good, but not as good as before.
wait 2 mins or so(at idle), then take off again like before, but this time and next several times only get a min or two of good ride time.
I did check coils with my hands, did not seem overly hot.
worth mentioning, about the 4th or 5th time of power loss, waiting, going well again for brief period, something odd happened.
as I took off and after planning off I immediately lost power like all the previous times for about 2 or 3 seconds, but before I touched anything, it jumped right back up and kept going for several more minutes.
Please advise.
My boat runs great for short periods of time, then bogs/ looses power, then goes back to running well (briefly).
This cycle of running good, power loss, running good again varies greatly, both run good, and wait time to run again.
Sometimes 5 min good run with 2 min wait, sometimes 30 sec good run with min wait, some times several min good run, wait time less than 30 sec. and runs good for 5 mins.
I have read as many related post to both mercury and other motors alike most all of them say fuel, in my case, I do not think its fuel.
Please read over what I have done so far, and give me any suggestions or similar problems that were solved.
Thanks in advance.
BOAT SIDE; 1990 Astro quickfire 16 F/S
1 Replaced fuel in tank.
2 Confirmed tank ventilation open.
2 Checked pickup tube.
3 Replaced fuel filter and water separator.
4 Replaced all fuel lines and clamps with 3/8" I.D.
5 Replaced primer bulb.
Motor Side; 1990 Mercury 90HP ELOPT 3cyl
Prop/motor/boat factory
Compression check WOT cyl-1 135psi, cyl-2 125psi, cyl-3 130psi checked twice. First time cyl-2 only 120psi
1 Replaced all fuel lines and clamps with 3/8" I.D.
2 Replaced fuel filter.
3 Replaced all other tubes hoses and clamps.
4 Rebuilt fuel pump 1st time OEM kit (only comes with plastic disc).
5 Rebuilt fuel pump 2nd time Sierra kit (has plastic disc and rubber valve).
6 Removed cleaned and rebuilt carbs.
7 Set floats to factory specifications.
8 While carbs were off, inspected reeds through intake manifolds.
9 Confirmed main jet and bowl vent orifice size.
10 Adjusted low speed mixture per OEM manual.
11 Timing/Synchronizing/Adjusting per OEM manual.
12 Confirmed good spark on muffs, idle.
13 Muffs @idle, ran on cyl1 only, cyl2 only,and cyl3 only (ran surprisingly well).
14 At lake When motor started to loose power, pumped bulb, was firm, no changes.
15 At lake When motor started to loose power, touched ea coil, not to hot and even.
16 Has new water pump. Also touched heads over ea cyl, not to hot and even.
After all this, It started first attempt, idled in gear @ 700 rpm perfectly.
hole shot was better than ever, WOT at 45 mph @ 5100 rpm for about 15 mins.
Suddenly looses power (as if lack of fuel) tach reads 3000 rpm, pumped primer again, no change.
move throttle from WOT to just under half rpm drop from 3000 to 2900, Seems to be powered correctly for that rpm range.
hold their for a min or two (to get out of the way) drop to neutral, idles good, but not as good as before.
wait 2 mins or so(at idle), then take off again like before, but this time and next several times only get a min or two of good ride time.
I did check coils with my hands, did not seem overly hot.
worth mentioning, about the 4th or 5th time of power loss, waiting, going well again for brief period, something odd happened.
as I took off and after planning off I immediately lost power like all the previous times for about 2 or 3 seconds, but before I touched anything, it jumped right back up and kept going for several more minutes.
Please advise.
