78 black max 175hp

[Curtisjames91]

I ran the motor today and it ran great until right before we headed back towards the boat ramp the motor kept bogging down and would die then I would have to choke it while giving it fuel to get it to start and it would bog down again I notice that it wasn't shooting water out of the tell tale but it was coming out of the exhaust ports we did idle the boat a lot today any ideas on what's going on? It ran fine all day then started bogging down anytime you give it fuel im lost

 

[jimmbo]

Welcome to iboats

Ok How long have you owned this motor? If so, was it winterized properly? You know... Stabilizer in the fuel... When was the water pump impeller changed? Tell tales often plug up and fishing some weed eater line can clear it out. Does the engine have a water pressure gauge? If not, why not?

It does sound like a lean condition, dirt/gum/jellylike guck in the fuel can clog up a carb, and that engine has 3 2bbl carbs

 

[Curtisjames91]

Thank you! We just bought the boat and the motor was on it. I have no experience with outboards just some limited experience with Diesel engines. I've not seen a water pressure gauge on the motor when we bought the boat it was hooked to muffs and water was coming out of the exhaust holes the motor started fine and ran fine so we assumed all was well

 

[racerone]

So you heard it run on a hose / muffs and all sounded fine ??-----Start the trouble shooting with a compression test.

 

[Curtisjames91]

Yep then we took it to the lake and it ran great bought the boat then took it out again now it starts this compression is 115 in all cylinders but one and it's 110

 

[Curtisjames91]

All the plugs look great as well little fuel oil mix on em could this be a fuel delivery issue? Where exactly is the fuel pump and I'm replacing the water pump assembly as well

 

[Teamster]

I have an old Merc 150,

I have an intermittent electrical issue with the ignition and sometimes it seems to drop the fire to a cylinder or two,...
I haven't been able to trouble shoot it yet,..

But, your issues sound kind of like mine,...

 

[Curtisjames91]

I doesn't seem to miss or drop a cylinder but I've been wrong before. I pulled lower unit off and checked out the water pump the rubber sleeve in the housing was smashed down and blocking some flow but when I pulled it out peices of it broke off and the rest was pretty brittle the new kit should be here this week. I'm sure I'm wrong on this but I'm hoping that once we get the water pump issue fixed the motor will run good. I still haven't located the fuel pump but still need to really look as well. Any input is appreciated

 

[racerone]

You asked for input.-----So do a compression test, based on the fact that the motor may have overheated.

 

[jimmbo]

Follow the fuel line from where it enters the cowl, it will go to the fuel pump.

 

[Curtisjames91]

Found the fuel pump replaced the water pump and did a compression check the compression came back the same as before 115 in all cylinders but one at 110 I'm getting water in the heads and it idles fine but no water coming out of the tell tale what's the deal? I've ran water through it backwards and it comes out so it's not clogged but it won't pee?

 

[Curtisjames91]

Anyone have any tips on why this thing won't produce water from the tell tale?

 

[Teamster]

Anyone have any tips on why this thing won't produce water from the tell tale?

I've had spiders and even wasps get in the tell tale and try to nest,....

Maybe try a pushing a small wire up and see if it is clogged.

 

[Curtisjames91]

I'm going to try some weed eater string when I get home. But I sprayed water through the tell tale hole and it came out of the mid but not the water tube is this normal?

 

[Curtisjames91]

Tried to run the weed eater string in as far as I could and didnt knock anything loose or out. sprayed some more water through and ran the motor again still not peeing I'm lost what the heck is wrong with this thing

 

[jimmbo]

Disconnect the telltale hose at block, this a long shot, but hoses can rot on the inside and develop internal check valves. In addition, if the impeller was self destructing, pieces of it may have gotten into block/heads

 

[Dukedog]

if it over heated enough ta bog it down it would be junk on compression by now.. there is a 3/4 pipe plug on top of tha motor.. pull it out and start on tha hose for a few seconds.. should get water flow there.. if so tha pump is probably good.. when it starts ta bog/die pump tha primer bulb ata rapid rate.. if motor picks up ya gotta fuel delivery problem.. probably tha pump......

 

[Curtisjames91]

Disconnect the telltale hose at block, this a long shot, but hoses can rot on the inside and develop internal check valves. In addition, if the impeller was self destructing, pieces of it may have gotten into block/heads

I did that and replaced the fitting and hose. The old impeller was whole and in good condition just the rubber piece that is in the cap under the plastic tube was brittle but whole as well so I went ahead and replaced it. It started to dribble a little last night but still nothing like I've seen on other motors.

 

[Faztbullet]

If I remember correctly the 78 model tattle tale comes off adapter plate ad not the t-stats so could be some debris in adapter stopping flow..

 

[Curtisjames91]

If I remember correctly the 78 model tattle tale comes off adapter plate ad not the t-stats so could be some debris in adapter stopping flow..

Ok thanks any recommendations on how to get the debris out? Or am I looking at disassembling the motor?