1993 135 Black Max Twins stalling

[kramerpage]

Last year they ran great. This year I have an increasing problem with the engines stalling.
Scenario 1... port is forward and starboard is in reverse to enter slip at idle

Scenario 2 both at idle and may run for 10 minutes fine and all the sudden on drops out and wont restart unless you activate enrichment button for 2 seconds.

Primer bulbs pump up rock hard but loose pressure in a few minutes of idle. I dont believe they are supposed to stay hard are they? I cant remember.

Anyway the marina put a new fuel pump rebuilt kit (mercury) on each motor this spring in addition to the usual new plugs and carb adjustments.

They tested the boat twice and say they cant duplicate the symptoms. Im thinking the fuel pump rebuild or air is the issue.
Where do I start? Thanks for any insight. Im headed up to the boat tonight to look at this issue Friday morning. I have a paper manual also.

Oh. One last thing sometimes when bringing the engines rpm up to take off on plane one will die like after 1800 rpm and I have to stop and restart and kinda feather back up. WOT is fine 5000-5200rpm 4000 is fine 3300 is fine which is planing rpm. Thanks for any advice. I am not a marine mechanic lol

 

[Chris1956]

Sounds like dirty carbs. Those motors are 25+ years old.

 

[kramerpage]

That is certainly possible Chris. I'm sure they need it right. Lol

I'm gonna bypass the anti siphon valve on each line inside the 200 gal tank and install 12 inch clear fuel line before the primer bulb in the am. I have guest coming at 5 pm to fish.

The carbs are a lot of work to soak and clean. I would need to do those I'm my garage 200 miles away and then bring them back up and mount them. I couldn't imagine what my Marina would charge.

I should have rebuilt carbs over winter like I wanted marina said not to since they ran so good last year.

 

[kramerpage]

Update
I removed anti-siphon valves from fuel tank. Problem continues. Check water separator filters and no water. Made a 1 to1 solution of seafoam and connected directly to each motor. Ran at idle for 10 minutes and let soak for an hour. connected main lines back up and test drove. Problem continues...Marinas Mercury mechanic was on vacation for a week...

 

[kramerpage]

I forgot I have a spare powerhead in the shed. I ordered 6 gasket kits 8107492, 3 floats 810738 thinking they cant all be bad, and 6 valve seat kits 811690. That way i can rebuild a set of 3 in the shed and take em up to the lake and install them. I got a gallon can of gunk cleaner to soak parts in. Its hell getting old and forgetting stuff...

 

[kramerpage]

I took the carbs off my spare power head. I see they are numbered 123 3 on bottom 1 on top.

my question is what's the difference between them? I'm guessing I rebuild them one at a time due to the differences.

 

[Chris1956]

The carbs usually have slightly different main jets in them, however, the main difference is that the fuel enrichener drains fuel from the top carb into the two lower ones when the choke is engaged. Also, there is an air valve for warm up, on the block. The output of that may be unique to a carb or two.

 

[kramerpage]

That is the only difference that I noticed also Chris. thanks for responding.
I had an issue with a progression fuel jet that would not come out. I heated it with a heat gun and got it out but the screwdriver channel is stripped going counterclockwise. Can I deburr the channel and reinstall it since I will be going clockwise. The orfice is fine?

 

[kramerpage]

Well I bought the gasket kit 8107492, the float 810738 and the valve seal kit 811690

My question is can I use the old bowl needle clip since it did not come with the 811690 kit?
Why would the sell a kit that has the seat, the gasket and the needle but no clip??? Unbelievable...
I cannot even find it on mercurys website catalog. Thanks for any insight. Guess Im not going to the lake