21v Fuel Pump Issues?

[mdk681]

Hi guys,

On our last trip out to surf this season, while under way my '99 21v died. It would crank but wouldn't even sputter, which led me to believe it was a fuel issue. Motor is the 350 MAG MPI. I crawled back by the motor in the locker and had a buddy click the key to the on position, and the normal buzz of the fuel pump appeared to be quite weak and sputter. Luckily my Dad was around and towed us back to the dock with the pontoon.

I tried to start the boat the next day to get it on the trailer and the same thing, weak fuel pump noise and would not fire. Took the boat to the shop where my trusted friend and owner said that the boat fired right up when he was trying to troubleshoot. Fuel rail pressure tested out as normal. He went ahead with the winterization, oil change, and fuel filter change as normal.

Is this a common issue when a fuel pump is starting to die? We are planning to look into it more in the spring, but my mechanic said that the fuel pump change is a fairly big job, and could possibly require removing one of the motor mounts and re-aligning the motor due to lack if access to the pump. He did not spend much time looking at it, and what it would take to get the pump out and replaced, that was just his first guess.

Any insight on this, or other items to look at? After searching around for a while it appears this is a fairly common issue with our 18ish year old boats. Should I just replace the pump regardless in the spring? Are the aftermarket pumps out there any good, or should I be using OEM Mercruiser parts?

Thanks in advance for the help,

[boatwakes]

Common issue on the mercruiser and symptoms are in line with what Ive seen during diagnosis. The job is not a big job. It's a pain in the *** but it's not a big job. The fuel pump is mounted to the motor mount on the starboard side of the engine but the mount doesn't have to be removed to change it. You will also want to purchase a new fuel pressure regulator kit and the brass adapter and crush washer that goes into the regulator, they break all the time if you try to remove them. It's another $150 but peace of mind. Stay with Mercruiser OEM parts on this one. Sierra makes an aftermarket pump but you need to buy the fuel pump kit from Mercruiser which includes all the necessary components the Sierra kit does not have. Use your serial number to purchase as there are 3 different style high pressure fuel connection fittings Mercruiser used on those pumps. It's a job you can tackle if you want, I did a DIY write up on it several years ago for the site. Good luck!

[mdk681]

Common issue on the mercruiser and symptoms are in line with what Ive seen during diagnosis. The job is not a big job. It's a pain in the *** but it's not a big job. The fuel pump is mounted to the motor mount on the starboard side of the engine but the mount doesn't have to be removed to change it. You will also want to purchase a new fuel pressure regulator kit and the brass adapter and crush washer that goes into the regulator, they break all the time if you try to remove them. It's another $150 but peace of mind. Stay with Mercruiser OEM parts on this one. Sierra makes an aftermarket pump but you need to buy the fuel pump kit from Mercruiser which includes all the necessary components the Sierra kit does not have. Use your serial number to purchase as there are 3 different style high pressure fuel connection fittings Mercruiser used on those pumps. It's a job you can tackle if you want, I did a DIY write up on it several years ago for the site. Good luck!

Thanks for the insight boatwakes. I was hoping that it wasn't as big of a job as he made is sound like. I have been searching for your DIY post for a while and can't seem to find it. Any idea where it is located, or do you have a link?

[mikemcclain8]

Something else to check

Hi guys,

On our last trip out to surf this season, while under way my '99 21v died. It would crank but wouldn't even sputter, which led me to believe it was a fuel issue. Motor is the 350 MAG MPI. I crawled back by the motor in the locker and had a buddy click the key to the on position, and the normal buzz of the fuel pump appeared to be quite weak and sputter. Luckily my Dad was around and towed us back to the dock with the pontoon.

I tried to start the boat the next day to get it on the trailer and the same thing, weak fuel pump noise and would not fire. Took the boat to the shop where my trusted friend and owner said that the boat fired right up when he was trying to troubleshoot. Fuel rail pressure tested out as normal. He went ahead with the winterization, oil change, and fuel filter change as normal.

Is this a common issue when a fuel pump is starting to die? We are planning to look into it more in the spring, but my mechanic said that the fuel pump change is a fairly big job, and could possibly require removing one of the motor mounts and re-aligning the motor due to lack if access to the pump. He did not spend much time looking at it, and what it would take to get the pump out and replaced, that was just his first guess.

Any insight on this, or other items to look at? After searching around for a while it appears this is a fairly common issue with our 18ish year old boats. Should I just replace the pump regardless in the spring? Are the aftermarket pumps out there any good, or should I be using OEM Mercruiser parts?




Thanks in advance for the help,

Probably not the cause, but in my 2005 22i there is a fuse box on top of the engine. I had intermittent trouble starting for a while and then finally nothing but cranking with no firing. I checked a lot of different things and couldn't find the culprit. Finally, I turned the key to accessory to listen and heard a faint clicking under the engine cover. Opened the box and had a melted fuse. Switched it out and all has been good since then. Just something else to check. The attached photo is not exact but similar to what I saw under the plastic cover.

tige fuse.jpg

[mdk681]

Interesting. My mechanic said that he traced voltage all the way to the pump so he believed that was not the issue. I will make sure we double check that in the spring though; always good to have a list of items to check.