iron ranger
Cadet
- Joined
- Jul 21, 2017
- Messages
- 7
Looking for suggestions here...
1984 sea ray 24' Sundancer with mercruiser 228 (305), quadrajet carb, thunderbolt IV ignition.
We had gone through the carb recently and adjusted the float level as it was a tad low. Test ran the rig and it was great. Throttled up great and up to around 30mph or so.
This past weekend we took her out for a fishing trip to Isle Royale on Lake Superior. We had 4 people on board as well as about 30 gallons of extra fuel. We started to make the crossing to the island and could not get up on plane. She would get to around 3000 rpm and pretty much hold there.
Went back to the marina to check out a few things such as fuel restriction in the anti siphon valve and that checked out fine. While we were messing with it, I also checked to see if she would throttle up to normal rpm in neutral. She would get up to the 5000 neighborhood just fine in neutral. We figured try leaving some weight at the dock and try it. Left two guys and a couple coolers and tried t out. I was able to get to about 3800 rpm and 22mph. We chalked it up to the extra fuel weight and went on our way since the weather was ok for a slow crossing. The crossing normally takes about 40 minutes and this time took 2 1/2 hours or so and burnt up about 3/4 tank of fuel that normally will use maybe 1/4.
While out there trolling, she was getting a bit hot so we pulled the thermostat (less than ideal but not much option). She would run at an ok temp then.
During the return crossing on Sunday we were able to get her up to around 3800 to 4000 and 22 mph or so but every once in a while she would start to lose power a bit and then gain again. This happened several times during the return crossing. Made it in about an hour with the spontaneous slow downs.
My thought is two things changed before returning.
1- thermostat removed and running cooler.
2- less weight as we used up the extra fuel.
Another thought I had, and I doubt it could be the issue but wondering if it could cause the lack of gaining rpm under load. I know there's a lead off the wiring harness by the ignition module or distributor that is intended to use as a ground to set base timing. Ok, so IF in theory somehow this lead got moved around and was making ground on the intake, etc, could this ground out cause the ignition not to advance the timing while under load and maybe at times would move so it wasn't making ground and then would allow it to advance, hence the fact that my return trip I was able to get up to around 4000 rpm?
Maybe 2 years ago we put in a new distributor, coil, ignition module, plugs, and wires but I am leaning toward the ignition module acting up since I have heard of guys having trouble with them and holding ice on them to temporarily clear the issue. Kind of matches the fact that we ran cooler on the return trip.
Any other thoughts or maybe ways I can try to confirm the ignition module is the problem? Also is there any good way to be sure the secondaries are opening at the right time on the quadrajet? That's also a thought I had since it seems like it should get a bit more power out of the hole to get up on plane.
Thanks for any input you guys might have. We have been fighting miscellaneous issues with this boat since we got it 5 years ago. Started that they swapped the block after freezing it and used an automotive delco distributor so that is why we had to change out everything to brand new thunderbolt components.
I know this is a long post, but I wanted to include as much info as I could right now.
Thanks for reading and any input you may have.
1984 sea ray 24' Sundancer with mercruiser 228 (305), quadrajet carb, thunderbolt IV ignition.
We had gone through the carb recently and adjusted the float level as it was a tad low. Test ran the rig and it was great. Throttled up great and up to around 30mph or so.
This past weekend we took her out for a fishing trip to Isle Royale on Lake Superior. We had 4 people on board as well as about 30 gallons of extra fuel. We started to make the crossing to the island and could not get up on plane. She would get to around 3000 rpm and pretty much hold there.
Went back to the marina to check out a few things such as fuel restriction in the anti siphon valve and that checked out fine. While we were messing with it, I also checked to see if she would throttle up to normal rpm in neutral. She would get up to the 5000 neighborhood just fine in neutral. We figured try leaving some weight at the dock and try it. Left two guys and a couple coolers and tried t out. I was able to get to about 3800 rpm and 22mph. We chalked it up to the extra fuel weight and went on our way since the weather was ok for a slow crossing. The crossing normally takes about 40 minutes and this time took 2 1/2 hours or so and burnt up about 3/4 tank of fuel that normally will use maybe 1/4.
While out there trolling, she was getting a bit hot so we pulled the thermostat (less than ideal but not much option). She would run at an ok temp then.
During the return crossing on Sunday we were able to get her up to around 3800 to 4000 and 22 mph or so but every once in a while she would start to lose power a bit and then gain again. This happened several times during the return crossing. Made it in about an hour with the spontaneous slow downs.
My thought is two things changed before returning.
1- thermostat removed and running cooler.
2- less weight as we used up the extra fuel.
Another thought I had, and I doubt it could be the issue but wondering if it could cause the lack of gaining rpm under load. I know there's a lead off the wiring harness by the ignition module or distributor that is intended to use as a ground to set base timing. Ok, so IF in theory somehow this lead got moved around and was making ground on the intake, etc, could this ground out cause the ignition not to advance the timing while under load and maybe at times would move so it wasn't making ground and then would allow it to advance, hence the fact that my return trip I was able to get up to around 4000 rpm?
Maybe 2 years ago we put in a new distributor, coil, ignition module, plugs, and wires but I am leaning toward the ignition module acting up since I have heard of guys having trouble with them and holding ice on them to temporarily clear the issue. Kind of matches the fact that we ran cooler on the return trip.
Any other thoughts or maybe ways I can try to confirm the ignition module is the problem? Also is there any good way to be sure the secondaries are opening at the right time on the quadrajet? That's also a thought I had since it seems like it should get a bit more power out of the hole to get up on plane.
Thanks for any input you guys might have. We have been fighting miscellaneous issues with this boat since we got it 5 years ago. Started that they swapped the block after freezing it and used an automotive delco distributor so that is why we had to change out everything to brand new thunderbolt components.
I know this is a long post, but I wanted to include as much info as I could right now.
Thanks for reading and any input you may have.
