Starting and maybe restoring old Mercury 402 40hp

[racerone]

Never heard of the concept of heating the fuel on a 2 stroke outboard.-----I know of / have seen fellows running motors fishing in January and February.------Seen them coming into view during a snow squall.------No fuel heaters on these Johnson motors !!----Fuel cooling maybe on a few Mercury models.

 

[The Force power]

Never heard of the concept of heating the fuel on a 2 stroke outboard.-----I know of / have seen fellows running motors fishing in January and February.------Seen them coming into view during a snow squall.------No fuel heaters on these Johnson motors !!----Fuel cooling maybe on a few Mercury models.

1st. we're talking Mercury not Johnson!
2nd. the late 70s 50 hp 4 cylinder or 65 hp 3 cylinder (I'm not sure) had small hoses running through the fuel-pump to pre-heat the fuel
How would it be cooling the fuel if the hot water from the head would run through the fuel-pump?!?
I guess that concept is often misunderstood

 

[racerone]

Talking nonsense you are !!

 

[The Force power]

Talking nonsense you are !!

have you ever been to China?

 

[racerone]

Fuel heating on an outboard is just a pile of nonsense !!-----Some folks just do not the simple things.---Explain why you would want to heat the fuel !!!

 

[The Force power]

Fuel heating on an outboard is just a pile of nonsense !!-----Some folks just do not the simple things.---Explain why you would want to heat the fuel !!!

For better combustion
see page #36

 

[The Force power]

Hmmm, it got quiet
I guess I was not talking nonsense!!!

 

[merc850]

The Merc 400 motor that preceded it had crank breakage problems due to owners over propping them which caused them to run under the rpm range, ie lugging; the fuel pump was water cooled to reduce the possibility of vapor lock and the mercury switch prevented overreving if the motor hit an underwater item that would kick it up. The shocks slowed the motor from rising into the air then cushioned it when reentering.

 

[racerone]

The fuel pump was water cooled.-----There is a huge amount of guessing in outboard motor land.

 

[The Force power]

The fuel pump was water cooled to reduce the possibility of vapor lock

Hi Merc850,

The particular fuel-pump I was Referring to was equipped on an early 70s 65 hp 3 Cylinder Merc. I'll have to take your word for it although I can't see HOW it would cool the fuel as this was connected to the hot side (tell-tail water)

 

[Faztbullet]

The tail tale is cool water as comes off lower transfer cover..

 

[The Force power]

The tail tale is cool water as comes off lower transfer cover..

Okay, I must have it all wrong
I apologies to all

 

[The Force power]

The fuel pump was water cooled.-----There is a huge amount of guessing in outboard motor land.

Yes, I guess I was!

 

[oldcab]

If reverse lock does NOT WORK the motor could tip up and over rev with prop out of the water.------Motor will not start ( no spark ) if operator has " ramp fever " and tries starting before checking if motor is in correct position !-----Find a better project motor.

ic, so makes sense the mercury switch is still a very important safety feature

as mentioned a few times now I do not intend to use this engine but also do not intend to bury it in landfill if it still works

It would be nice to have the serial# of the outboard so we would know exactly what unit we're talking about
(2) it has everything to do with in reverse because when the reverse-lock would not work the motor / LU will pop out of the water
(3) and is routed through the fuel-heater/pump
(4) Yes, you're correct

2) my setup got electric tilt trim, that should be safe
3) checked the fuel lines today, definately already routed correctly as per service manual, but missing the lines to the quick release coupler and check valve

and water definately for cooling fuel and pump

tested compression multiple times today
150/155psi

seems to be no spark or weak, i dont have fuel tank with me so no attempt to start it, will confirm when i test the stator etc when i have a chance, wirings seems shot, will see if it's the wiring or stator itself, will go from there

 

[The Force power]

ic, so makes sense the mercury switch is still a very important safety feature

as mentioned a few times now I do not intend to use this engine but also do not intend to bury it in landfill if it still works


2) my setup got electric tilt trim, that should be safe
3) checked the fuel lines today, definately already routed correctly as per service manual, but missing the lines to the quick release coupler and check valve

and water definately for cooling fuel and pump

tested compression multiple times today
150/155psi

seems to be no spark or weak, i dont have fuel tank with me so no attempt to start it, will confirm when i test the stator etc when i have a chance, wirings seems shot, will see if it's the wiring or stator itself, will go from there

You could check if the Mercury-switch is still good by soldering a new wire on & check for continuity by tilting it (bench-testing is easier)
(2) You can hook a fuel hose with primer bulb directly to that & just drop the other end in a fuel jug (jerry can)
You have not mention the serial# so it hard to pin point the exact engine you have, here is link to diagnose the ignition for what ever version you have

Page 16 - Mercury Mariner outboard ignition troubleshooter

Procedures for testing Mercury Mariner outboard motors.

www.outboardignition.com

 

[oldcab]

You could check if the Mercury-switch is still good by soldering a new wire on & check for continuity by tilting it (bench-testing is easier)
(2) You can hook a fuel hose with primer bulb directly to that & just drop the other end in a fuel jug (jerry can)
You have not mention the serial# so it hard to pin point the exact engine you have, here is link to diagnose the ignition for what ever version you have

Page 16 - Mercury Mariner outboard ignition troubleshooter

Procedures for testing Mercury Mariner outboard motors.

www.outboardignition.com

yup thanks, i'll check the mercury switch last as that's the least important for now, probably easiest way is unscrew it and aligator clip the terminals to a multimeter?

would I need to connect a check valve for the fuel tank or that could be skipped for now?

just tested the stator, red blue wire / within specs
checked the trigger, within specs
one coil is within spec 900 ohms, but the other coil is 5000 ohms which isn't, but the connections inside the coil to the bad one seems charred, although I doubt cleaning it will help

from my understanding I can't check the switch
also I can't find the spec for the yellow/yellow wiring for the stator

but the wires for the stator are shot anyway, to sell this engine to anybody as a working unit I will probably want to have to replace at least the stator, found one local one for about $300

will try to pull the flywheel when I have chance, I've already marked them, will have a close look at the stator to see if I could get right to the windings to solder new wires, never took one apart before, but if I could bandaid fix it, at least I could confirm how much parts I need to get it working if it's worthwhile

oh yea, I'll try to find the serial number too

 

[The Force power]

yup thanks, i'll check the mercury switch last as that's the least important for now, probably easiest way is unscrew it and aligator clip the terminals to a multimeter?

would I need to connect a check valve for the fuel tank or that could be skipped for now?

just tested the stator, red blue wire / within specs
checked the trigger, within specs
one coil is within spec 900 ohms, but the other coil is 5000 ohms which isn't, but the connections inside the coil to the bad one seems charred, although I doubt cleaning it will help

from my understanding I can't check the switch
also I can't find the spec for the yellow/yellow wiring for the stator

but the wires for the stator are shot anyway, to sell this engine to anybody as a working unit I will probably want to have to replace at least the stator, found one local one for about $300

will try to pull the flywheel when I have chance, I've already marked them, will have a close look at the stator to see if I could get right to the windings to solder new wires, never took one apart before, but if I could bandaid fix it, at least I could confirm how much parts I need to get it working if it's worthwhile

oh yea, I'll try to find the serial number too

You can check the switch on the motor while tilted up for continuity strip the wire as close as possible at the switch.
The check-valve in the quick-connect has no other function then to prevent fuel leaking out of the hose WHEN disconnected, so no you don't needed right now.

"from my understanding I can't check the switch"
What switch are you referring to??
The two yellow wires are the charging-circuit, I don't know the reading either you can remove one of the connected to the rectifier (for now)
Mercury wiring on engines of this age are all deteriorated, You WILL have to replace most if not all wires inside the cowl, remove the stator and solder on new sets of wires. (as close as you can get onto the old wires)
Pay close attention to all the wire leading to the switch-box.
REMEMBER...bad wiring/connections lead to bad diagnoses

this project will be a be a labor for love, by the time your done you won't want to sell it.
"

 

[oldcab]

You can check the switch on the motor while tilted up for continuity strip the wire as close as possible at the switch.
The check-valve in the quick-connect has no other function then to prevent fuel leaking out of the hose WHEN disconnected, so no you don't needed right now.

ic

"from my understanding I can't check the switch"
What switch are you referring to??

was referring to the switch box (332-4911A 8)

The two yellow wires are the charging-circuit, I don't know the reading either you can remove one of the connected to the rectifier (for now)

yea i got the values, they range from 0.15-0.2 depending on the output of the alternator, so it's not something I could measure with my meter

Mercury wiring on engines of this age are all deteriorated, You WILL have to replace most if not all wires inside the cowl, remove the stator and solder on new sets of wires. (as close as you can get onto the old wires)

yup, will try to check out the stator tomorrow, but now I'm baffled at lack of spark, as there is only 2 possible reasoning, 1) switch box, 2) ignition leads, as everything else checks out although wires a bit frayed but the right readings at the terminals, will have to see if I could get hold of a spark tester

Pay close attention to all the wire leading to the switch-box.
REMEMBER...bad wiring/connections lead to bad diagnoses

yup i've took photos of everything and traced all wirings and the colours matches the circuit in service manual

this project will be a be a labor for love, by the time your done you won't want to sell it.
"

yea all a bit of fun for me, never worked on a marine engine before, but if I have to start throwing money at it then it won't be worthwhile, looked at the internal and external harness, not cheap, so will see whether I could solder new ones myself otherwise not throwing $1000+ as most likely I will need to recon the carby, and still got the lower unit to play with, just got a bit of spare time while I wait for a 4 stroke so nothing to lose till I start throwing money at it

 

[oldcab]

quick update, I made some new battery cables to ensure a good ground because I tried cranking it last and it won't crank thought the solenoid went bad, but new cables sorted it out, and bonus now there is strong spark 6-8mm easily on both coil

I'm pretty confident the engine will start now with good compression and now spark

looks like the engine already good to begin with, just wanted to go through everything as I didn't want to damage it as I didn't know when it was last started

so if it starts, i'll need a minimum new impeller, new LU oil, try to rewire the stator, and see how much wiring I could fix, so should get this up and running for less than $1,000 for anyone that needs it, even with new stator and external harness, better than sitting in landfill

 

[The Force power]

quick update, I made some new battery cables to ensure a good ground because I tried cranking it last and it won't crank thought the solenoid went bad, but new cables sorted it out, and bonus now there is strong spark 6-8mm easily on both coil

I'm pretty confident the engine will start now with good compression and now spark

looks like the engine already good to begin with, just wanted to go through everything as I didn't want to damage it as I didn't know when it was last started

so if it starts, i'll need a minimum new impeller, new LU oil, try to rewire the stator, and see how much wiring I could fix, so should get this up and running for less than $1,000 for anyone that needs it, even with new stator and external harness, better than sitting in landfill

That good news but check the oil in the LU first before you do anymore work!