Ok, first time poster very new to engine maintenance/repair. Any help is greatly appreciated.
I have two 2006 Mercury 4-Stroke 15hp engines with the same (or at least a very similar) issue that are both giving me fits. I’m hoping someone on here can help me out.
Some background: both engines have been run for at least an hour or two per day, 3-6 days a week, probably since they were brand new - with only a month or two truly “off” throughout the year until recently. They are console controlled and are mounted on boats that are stored outside in Florida. Their primary use is as coaching boats for a rowing team.
Both recently sat unused for a while, for two different reasons:
Engine #1 was not used for 2-3 months due to a steering issue with the helm that made it difficult to operate. It was not needed for those months, so repair of that issue was not a huge priority, and it sat.
Engine #2 backfired (fairly explosively…it blew the cowl lid partly off) and caught fire in May 2016. It had to be doused with a chemical marine fire extinguisher. For various reasons, it sat unused after that until this month.
So, here’s where the issues started:
After correcting the steering issue with Engine #1, I tried to get it back into service on a regular basis. However, it soon started acting up – it would be difficult to start, and when it would start, it would idle well and accelerate well before losing pressure in the bulb on the tank hose and cutting out after less than 5 minutes of the throttle being open. So, I started troubleshooting…replaced some old and worn fuel lines, the old bulb, new fuel, etc…nope. Took the carb apart and found some gunk, which I blasted out with carb cleaner. Issue was less prevalent, but still kept popping up. Checked the spark plugs, and they were very dirty...replaced those, and it ran great that day, minus a slight difficulty shifting from neutral to forward and vice versa (almost like the engine was on the verge of dying during the shift as it got more gas before catching again and accelerating).
The next time I tried to use it, however, it started very rough and was fairly violently shaking when it did catch. The bulb was staying hard this time though, and the shaking smoothed out and it idled well, but it would die every time I tried to shift up into gear or back down from forward to idle without some very, very careful throttlemanagement. If it died, it would be a very major hassle to restart, but I managed to keep it going enough to finish out the day and make it back to the dock.
Engine #2 was a very similar story – I started with the carb because I knew it was still full of extinguisher chemicals. Got all those out and cleaned it thoroughly. Changed out the spark plugs, changed any bad fuel lines, etc. before I tried to run it. It idled a little high when I took it out for a spin, but otherwise ran fine…until it didn’t. Lost fuel pressure in the bulb and petered out. I found a loose screw on the fuel pump that was allowing fuel to leak out and air to leak in…I fixed that, and the bulb stayed hard after that maintenance, just like engine #1. I tweaked the idle back down to where it should be, and the engine ran great for about 20 minutes (minus, again, a slight difficulty shifting from neutral to forward and vice versa). However, it died during one of those shifts. Restarted no problem. Died again a few minutes later. Restarted with some trouble, ran in neutral fine, but then only went forward for about 50 feet before it petered out again. From there, I only managed to restart it once after about 10 minutes, and it promptly died during the shift to forward. Couldn’t restart it again after that. Had to get a tow back to the dock.
Given that both of these engines are 15hp four stroke Mercurys from 2006 with very similar use histories, maintenance schedules, both sat unused for a few months (a little longer in #2’s case) etc., my first thought is obviously that they’re suffering from the same issue or a very similar issue. I just can’t figure out what that issue might be at this point. Is it a bad fuel pump on both engines? Something else entirely? Something as silly as needing new oil?
Again, I’m very new to outboard engine maintenance. Any help would be very much appreciated.
I have two 2006 Mercury 4-Stroke 15hp engines with the same (or at least a very similar) issue that are both giving me fits. I’m hoping someone on here can help me out.
Some background: both engines have been run for at least an hour or two per day, 3-6 days a week, probably since they were brand new - with only a month or two truly “off” throughout the year until recently. They are console controlled and are mounted on boats that are stored outside in Florida. Their primary use is as coaching boats for a rowing team.
Both recently sat unused for a while, for two different reasons:
Engine #1 was not used for 2-3 months due to a steering issue with the helm that made it difficult to operate. It was not needed for those months, so repair of that issue was not a huge priority, and it sat.
Engine #2 backfired (fairly explosively…it blew the cowl lid partly off) and caught fire in May 2016. It had to be doused with a chemical marine fire extinguisher. For various reasons, it sat unused after that until this month.
So, here’s where the issues started:
After correcting the steering issue with Engine #1, I tried to get it back into service on a regular basis. However, it soon started acting up – it would be difficult to start, and when it would start, it would idle well and accelerate well before losing pressure in the bulb on the tank hose and cutting out after less than 5 minutes of the throttle being open. So, I started troubleshooting…replaced some old and worn fuel lines, the old bulb, new fuel, etc…nope. Took the carb apart and found some gunk, which I blasted out with carb cleaner. Issue was less prevalent, but still kept popping up. Checked the spark plugs, and they were very dirty...replaced those, and it ran great that day, minus a slight difficulty shifting from neutral to forward and vice versa (almost like the engine was on the verge of dying during the shift as it got more gas before catching again and accelerating).
The next time I tried to use it, however, it started very rough and was fairly violently shaking when it did catch. The bulb was staying hard this time though, and the shaking smoothed out and it idled well, but it would die every time I tried to shift up into gear or back down from forward to idle without some very, very careful throttlemanagement. If it died, it would be a very major hassle to restart, but I managed to keep it going enough to finish out the day and make it back to the dock.
Engine #2 was a very similar story – I started with the carb because I knew it was still full of extinguisher chemicals. Got all those out and cleaned it thoroughly. Changed out the spark plugs, changed any bad fuel lines, etc. before I tried to run it. It idled a little high when I took it out for a spin, but otherwise ran fine…until it didn’t. Lost fuel pressure in the bulb and petered out. I found a loose screw on the fuel pump that was allowing fuel to leak out and air to leak in…I fixed that, and the bulb stayed hard after that maintenance, just like engine #1. I tweaked the idle back down to where it should be, and the engine ran great for about 20 minutes (minus, again, a slight difficulty shifting from neutral to forward and vice versa). However, it died during one of those shifts. Restarted no problem. Died again a few minutes later. Restarted with some trouble, ran in neutral fine, but then only went forward for about 50 feet before it petered out again. From there, I only managed to restart it once after about 10 minutes, and it promptly died during the shift to forward. Couldn’t restart it again after that. Had to get a tow back to the dock.
Given that both of these engines are 15hp four stroke Mercurys from 2006 with very similar use histories, maintenance schedules, both sat unused for a few months (a little longer in #2’s case) etc., my first thought is obviously that they’re suffering from the same issue or a very similar issue. I just can’t figure out what that issue might be at this point. Is it a bad fuel pump on both engines? Something else entirely? Something as silly as needing new oil?
Again, I’m very new to outboard engine maintenance. Any help would be very much appreciated.
