150 Mercury XRI no power and hard start

**Se7** · 06-20-2022, 05:40 PM

I would like to suggest something I have seen a number of times in the last 50 years on boats that have been sitting and then brought back to life. The guys have given you a lot of great ideas. If all your diagnostics are correct , you could have a partially plugged exhaust sytem. The engine will idle well, but will have little power, start hard and all 6 cylinders will be hitting with wet looking plugs. Rodents like to crawl thru the prop hub and make a nest of rags, insulation, and or other debris above the carrier and plug the exhaust. (typically mice and or chipmunks). You would think the debris would blow out, but it typically does not. You can pull the prop and get a good light and look up in the exhaust for a restriction. Sometimes you have to pull the GC to be sure. The other tip is the engine will be quieter than normal on a flush device in the driveway. It will not have the cackle or bark we 2 stroke guys love to hear. (when you rev it up) The other scenario from storage is a nest under the hood and the first time you go WOT, the debris is sucked into the reeds and again causes low power, but typically the idle suffers. Know this is off the wall, but have seen it many times on units that have been stored. Hope this helps. if not something to think about. We always used to say you need 4 plus things for an engine to run properly Intake, Compression, Power, Exhaust and a place for the Exhaust to go freely. Thanks Dave IN MN

**Nuckolsn** · 06-23-2022, 10:05 PM

Interesting
it does seem quieter in the water than I remember
if the exhaust is plugged would it still rev out of gear?

**Nuckolsn** · 06-23-2022, 10:10 PM

I have a small update
I have fixed the hard starting issue with a new head temp sensor

Still won’t plane out but I now don’t have to give it throttle to get it started, it starts first bump of the key like it used to.

I have discovered that neither of my rectifiers are working as well, could they be causing my power issue? I always assumed they were only used for charging the battery. Since they need replacement anyway, whether it’s my power problem or not, does anyone have a recommendation on which brand is better?

**Se7** · 06-23-2022, 10:12 PM

Yes it will have good throttle response in neutral, but will be a real pooch in gear on the water.
If you have a flushing device , run it on the trailer in driveway and see it seems to be a bit muffled and does not have that 2 stroke cackle when you flash the throttle (rev it up). Many times you can see the obstruction by just pulling the prop. Worth checking out, costs nothing. Good luck. By the way, think it was mentioned a GC that is starting to tighten up will be very doggy on the water, but they typically will lock up in fairly short order.

**rgsauger** · 06-23-2022, 10:24 PM

Everybody has opinions on the rectifiers. Honestly, I have found that the $25 eBay units seem to work as well as anything. It is a combination rectifier/regulator. There might be better ones out there but I don’t have experience with them.

**rgsauger** · 06-23-2022, 10:25 PM

Do you have a pair of 20 amp rectifier/regulators or do you have a 40 amp combination unit?

**Nuckolsn** · 06-23-2022, 10:26 PM

There are 2 rectifiers on mine

**rgsauger** · 06-23-2022, 10:31 PM

I am pretty sure that they are rated at 20A each. Like I said, I have used the ones off of eBay/Amazon and they have worked for me. I think CDI also offers them. Theirs are probably better quality.

**rgsauger** · 06-23-2022, 10:37 PM

https://www.cdielectronics.com/product/194-5279/

https://www.amazon.com/Perfermance-R...%2C141&sr=8-21

Honestly don’t know if there’s any discernible difference between the two. Others might have thoughts on this

**Nuckolsn** · 06-23-2022, 10:38 PM

10-4
Thanks for links

**OnPad** · 06-23-2022, 10:47 PM

Good catch on the temp sender.

Bad regulators, will cause some issues with the fuel supply (ecu, fuel pump). I might get some flack for this, but it's hard to argue with the price of the ones on ebay. Just make sure you have a good fire extinguisher. Or you could damn near buy a blown up motor, with regulators, for the price of genuine mercury regulators.

**Nuckolsn** · 08-05-2022, 03:33 PM

Just as an update I haven’t really done much else besides changing the rectifiers and every single piece of rubber fuel line as a precautionary measure.
my tach now functions but I have not had time to test on the water.
Just trying to keep the thread alive because I fully intend to post my fix when/if I find it.

**rgsauger** · 08-05-2022, 05:10 PM

If your tach is now working, you're at least heading in the right direction

**Nuckolsn** · 08-17-2022, 12:12 PM

Just as I thought no change
I now know that I can’t get above 1100 rpm’s
I also noticed something that I hadn’t really noticed until today
The motor is extremely quiet in the water, atleast not as loud as I remember
Im going to drop the lower unit and have a look to see if I have an obstruction as the poster at the top of the page suggested
Ill keep you posted