Force dual stage Fuel pump

[The Force power]

I found in an old post something applies to me, as my fuel pump is square & I think this is what mine is.
please see below old posting & if someone knows the part# for the repair-kit; please let me know

Force 90 dual stage fuel pump

The pulses from the by-pass port which is fed through the small hole in the by-pass port cover and the hose from the crankcase acting against the diaphragm is what makes the fuel pump work. The one-way check valves keep the fuel flowing in one direction inside the pump and out to the carbs. Looks like the spring and washer (item #7 & #12) on the modified version positions the diaphragm to maybe push more fuel with each pulse.

NOTE: I installed the newer square type Mercury fuel pump on an old 1988 125 HP motor. I got a used by-pass cover and fuel pump from a later model motor on-line. The by-pass cover bolt pattern and size are the same for many of the motors. Just need one that matches up to the correct type of fuel pump. The newer square pumps have a different type of check valve(s) and they are included with the re-build kits. Plus the rebuild kits are cheaper for the Mercury style fuel pumps.

 

[The Force power]

Here's a link to a diagram

this is the original, I have the "up dated" pump

I think I found one, thanks anyway

 

[jerryjerry05]

Both pumps are good.
In 35 years I have only seen 1 check valve in the old style pump go bad.
It was in one of my motors.
I was changing the 5$ diaphragm and the valve fell apart without touching.
But it still worked??

The square pump has plastic valves that can bend when you have a backfire.

Very important, the gasket on the port cover. Once you mess with the cover, replace with a new
gasket and use a sealer/silicone and let it cure before you try to start.

The gasket leaks and can cause a lean condition and backfiring.
One good backfire can blow the rest of the gaskets.
To test: can of starting fluid sprayed around the intake side.
Any changes in the way it run |?? Then it might be sucking air.

 

[The Force power]

Both pumps are good.
In 35 years I have only seen 1 check valve in the old style pump go bad.
It was in one of my motors.
I was changing the 5$ diaphragm and the valve fell apart without touching.
But it still worked??

The square pump has plastic valves that can bend when you have a backfire.

Very important, the gasket on the port cover. Once you mess with the cover, replace with a new
gasket and use a sealer/silicone and let it cure before you try to start.

The gasket leaks and can cause a lean condition and backfiring.
One good backfire can blow the rest of the gaskets.
To test: can of starting fluid sprayed around the intake side.
Any changes in the way it run |?? Then it might be sucking air.

Thank you Jerry

 

[The Force power]

Something odd going on;

My motor is supposedly a 1990 but is equipped with a square fuel pump that was not till 1992 and on.

Anyways........my repair manual is not covering that particular pump (square one) I have the parts now but the You tube videos are conflicting as far as the clear Wafers & rubber Wafers is concern.
(I've seen both being used & only clear ones)

Do I ONLY use the clear Wafers OR Both

 

[jerryjerry05]

The parts diagram shows the 2 pieces go on together.
The pump must have been updated.
Yours is a 90/90 hp.

The ones I rebuilt only had the clear plastic in them????
Find a parts diagram?
Maybe the manual?
I have a Mercury 225 2002 manual and it shows the clear valves.

 

[The Force power]

The parts diagram shows the 2 pieces go on together.
The pump must have been updated.
Yours is a 90/90 hp.

The ones I rebuilt only had the clear plastic in them????
Find a parts diagram?
Maybe the manual?
I have a Mercury 225 2002 manual and it shows the clear valves.

Thanks jerryjerry,

if the pump was updated, I would still have that "bone-shaped" cover-plate and I don't??
all this does not matter much to me if this is a slightly newer motor, but I had bought the repair Manual based on a 1990 B-model

 

[The Force power]

Found it!!
http://boatinfo.no/lib/mercury/manuals/mercury_1965-1989_2-40.html#/0

 

[The Force power]

Now that mine does not have "the bone-shaped" cover-plate, where are the screens(if any) for the re circulation hoses?

 

[Redbarron%%]

The screens are located in the check valve / fittings on the block.

 

[The Force power]

The screens are located in the check valve / fittings on the block.

oh, so it's like the Mercs

thank you

 

[jerryjerry05]

IF??? you have a 1990 B modelor A and C D EFG
They all have the dog bone shaped cylinder drain cover.
The 90 has a screen on one side and a small reed and keeper on the other.
There is 2 different gaskets for the assy.
The screens are available on e-bay
They stopped the dog bone late 92 on some later models.

Post a pic of the stbd. side.
If you have no dog bone then someone's replaced the 90 with a newer block?????

 

[The Force power]

IF??? you have a 1990 B modelor A and C D EFG
They all have the dog bone shaped cylinder drain cover.
The 90 has a screen on one side and a small reed and keeper on the other.
There is 2 different gaskets for the assy.
The screens are available on e-bay
They stopped the dog bone late 92 on some later models.

Post a pic of the stbd. side.
If you have no dog bone then someone's replaced the 90 with a newer block?????

thank you Jerry, I will

I suspect a newer power head maybe; the midsection has 89 stamped in it

 

[The Force power]

I was able to upload the one Power head I have

 

[jerryjerry05]

That is a newer block.
Someplace on the top cyl. near the port cover is a foundry stamp.
There or on the bottom of the intake.
The center # is the year it was made.

 

[The Force power]

That is a newer block.
Someplace on the top cyl. near the port cover is a foundry stamp.
There or on the bottom of the intake.
The center # is the year it was made.

well if that the case, the power head is a 1997

thank you Jerry

 

[The Force power]

I can't see how, but;
Will leaking Re-circulation hoses and/or plugged check-valves affect the fuel pump delivery and ultimately the Carburetors?

 

[jerryjerry05]

.

Explained to me: if the check valves or hoses become blocked the fuel can pool
and get back into the carbs making a rich or too much fuel on different cyl.​

 

[The Force power]

.

Explained to me: if the check valves or hoses become blocked the fuel can pool
and get back into the carbs making a rich or too much fuel on different cyl.​

That I can see happening, thanks Jerry

Behind the square pump is a kind of odd shaped cover-plate with gasket, do you know what's behind it?

I normally would take it off & loo myself but the motor is up at camp (still not running)

 

[jerryjerry05]

That's a port cover.
Should be 3 of them.
It's for the intake of fuel into the cyl.
You remove it you can see the side of the piston and rings through the intake holes.
Unless your running bad, or it's backfiring or coughing leave it alone.

To test the seals, can of stating fluid, start motor and spray the SF around the port covers and intake manifold..
If the spray makes any difference? there might be a bad gasket?

IF you take it off?? make sure the NEW gasket has sealer.
These gaskets usually are good but 1 tiny backfire, cough or stutter can blow the gasket and allow the motor to suck air and make the motor run bad.