Mercury 1988 200hp blackmax Carb issue

**rock** · 04-07-2022, 07:13 AM

That doesn't matter.

Rock

**FUJIMO** · 04-07-2022, 09:05 AM

...the fuel/water separator is sufficient, but its up to you if you want to add another small inline filter on the motor...

**rgsauger** · 04-07-2022, 11:03 AM

My pump feeds #2 carb on port side. Then there is a T-fitting on starb side that feeds #1 and #3 bowls. Make sure to use a 5/16" filter (not 1/4") in your fuel line so that the ID of the fitting is large enough.

Glad you got your problem resolved!

**gflick** · 04-10-2022, 03:17 PM

So I took it out to the lake today and issue persists. Motor bogging down when I give it some throttle. Can’t seem to get past 1.5k rpms without bogging down. It did manage to get up to 5k rpms twice in the couple of test runs I did and ran great while it was there. I’ve had this issue since I’ve bought the motor. Decided to clean out the carbs and replace all old fuel line and spark plugs.

Also noticed today after I slowed down from the only top end run I could manage that the water pump outlet was pure steam... is this normal? When the motors cool there’s a steady stream of hot water. After a running the engine for a bit it was pure steam coming out. Decided to shut it off and call it a day after seeing that to avoid possible damage.

anyone have any ideas what could be causing these things? I bought the boat a month ago

**rgsauger** · 04-10-2022, 10:56 PM

Do you know when the water pump was last changed? Might be worth yanking the thermostats and making sure that they are clean and functioning. You can put them in a pot of water on the stove with a grease or meat thermometer and watch them open at a given temp.

Do do you know if this motor has pretty much been left alone or if it has had a few things replaced over the years? If the former, then it would be a good idea to replace BOTH switchboxes. Sierra made in Germany. About $300 for pair. Also ohm out your trigger and stator per the book.

**gflick** · 04-10-2022, 11:06 PM

Originally Posted by rgsauger

Do you know when the water pump was last changed? Might be worth yanking the thermostats and making sure that they are clean and functioning. You can put them in a pot of water on the stove with a grease or meat thermometer and watch them open at a given temp.

Do do you know if this motor has pretty much been left alone or if it has had a few things replaced over the years? If the former, then it would be a good idea to replace BOTH switchboxes. Sierra made in Germany. About $300 for pair. Also ohm out your trigger and stator per the book.

Two previous owners as far as I’m aware. Guy I bought it off of said he hadn’t had anything rebuilt. Just usual maintenance. I can tell there’s been carb work done to it before by a mechanic of some sort. I’d imagine if there was carb work that was paid to be done there may have been other stuff.

plan to remove the lower unit for gear oil and I’ll inspect impeller then as well. Maybe other stuff while I have it off? I’ll also check out thermostat. Do I need to take off the cylinder head for that? Or alternate method.

Will check stator and trigger with multimeter as well. Could these be potential causes for a bog down though?

I appreciate the input sauger!

**gflick** · 04-10-2022, 11:15 PM

Oh also what switchbox are you referring to? Sorry I’m brand new to the outboard world. Learning as I go

**rgsauger** · 04-11-2022, 11:51 AM

Definitely plan on replacing your water pump - don't just "check". It's not hard when you have the lower dropped. "sierra" brand is fine

The downlow bog can be from a stator that's going out. There is a low side and a high side to it. Your motor is 34 years old so not unreasonable for it to crap out. Mine just did last year. You can find good used ones here and there for not much $.

The switchboxes control the distribution of spark to each coil and spark plug. There are a pair of them stacked on the Starb side of the motor. If these are stock, then it's 100% time to replace them. when they go, they either start dropping one or more cylinders OR they can double-fire one or more plugs. The latter is NOT good and bad times are waiting just around the bend. $300 for pair.

thermostats are on top of heads with hoses going to them. two bolts. No need to yank a head.

Since your compression is good, then your motor is most probably sound. It just needs a little love and updating to be a great motor.

REALLY plan to yank the oiler and go to premixing. If (when) the oil pump gear strips (and it will), then you're SOL real darn quickly. Yank the black boxes. Get it down to simple and reliable and enjoy for years to come.

**Merc 2.5** · 04-11-2022, 05:10 PM

To change gear oil you do NOT have to drop lower , but for pump yes

**gflick** · 05-28-2022, 11:23 PM

Originally Posted by rgsauger

Definitely plan on replacing your water pump - don't just "check". It's not hard when you have the lower dropped. "sierra" brand is fine

The downlow bog can be from a stator that's going out. There is a low side and a high side to it. Your motor is 34 years old so not unreasonable for it to crap out. Mine just did last year. You can find good used ones here and there for not much $.

The switchboxes control the distribution of spark to each coil and spark plug. There are a pair of them stacked on the Starb side of the motor. If these are stock, then it's 100% time to replace them. when they go, they either start dropping one or more cylinders OR they can double-fire one or more plugs. The latter is NOT good and bad times are waiting just around the bend. $300 for pair.

thermostats are on top of heads with hoses going to them. two bolts. No need to yank a head.

Since your compression is good, then your motor is most probably sound. It just needs a little love and updating to be a great motor.

REALLY plan to yank the oiler and go to premixing. If (when) the oil pump gear strips (and it will), then you're SOL real darn quickly. Yank the black boxes. Get it down to simple and reliable and enjoy for years to come.

Just got back into working on the boat today. Last months been busy. Changed out the water pump ( Impeller) and changed gear oil. I also tested my thermo stats in some boiling water on the stove and they both never opened. So i think i found the culprit to my overheat issue.

Next issue is the bog down... Im thinking it could be stator like you said. Is there anyway to test this with a multimeter? Im looking into changing out switchboxes as well as they look to be stock. Appreciate all the help!

**waveskimmer** · 05-29-2022, 10:10 AM

Yes it can be tested with a multimeter, but you'll either need to make or buy a dva adapter.

You'll need this too: https://www.cdielectronics.com/wp-co...g-Guide_RS.pdf

**gflick** · 05-30-2022, 01:58 PM

Just purchased new sierra stator and some switchboxes off amazon. Coudn't find sierra or quicksilver switch boxes on amazon so i went with some china crap that had good reviews. I really want to remove the oil injection system but cant seem to find a proper kit for my engine. Any advice?

**rgsauger** · 05-31-2022, 12:15 AM

I’m gonna BEG you to run the good Sierra stuff from Germany instead of chinky crap. Good reviews mean chit if they start double firing and melt your motor. I’ll look for ya.