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slorole
10-17-2011, 11:37 PM
Hello every one
I have acquired a 1978 mercury 800 80hp that has been setting for about 15 years.
Electrolysis had set in and destroyed most of the wiring so first things first I checked
The compression and its running 130 to 135 all four cylinders, so I began the task of
Replacing the electrical.
Replaced the stator, the trigger and the whole wiring harness, thoroughly cleaned the carb's

Replacing all gaskets, replaced all fuel lines.
Done the Timing Point Adjustment
But when doing the Primary Pickup Synchronizing Timing it look as throw the cam never touches
The carb pin all the way throughout the first cam cycle.
I can get the engine to run but only till itís put in gear and it stallís and dies.
I believe it has to do with the timing but thatís back to the cam issues .
Can the cam be wore that bad are am I missing something.
Bi the way, Iím doing this from the seloc manual.

racerone
10-18-2011, 08:33 AM
First of all that cam does not always have to touch and you had best not move anything on the timing untill you are 110% sure that needs to be adjusted !!----------------Timing on an outboard is fixed and normally does not need adjusting !!!--------------So look for the real issue here and it may be time to revisit carburetor cleaning.------They have to be taken apart for cleaning !!

slorole
10-18-2011, 08:51 AM
They have to be taken apart for cleaning at local shop but I'm taking them apart again now to clean and check float adjustment's.

racerone
10-18-2011, 09:25 AM
Not hard to do yourself , but maybe all it needs is for low speed jets to be opened up.

slorole
10-18-2011, 12:29 PM
well after 3 hr of cleaning, setting the float's. it still has the same issues.
I'm starting to think its set up so long that the reeds cant handle it.

racerone
10-18-2011, 12:51 PM
I don't think it is the reeds , unless one is held open by debris.------------They are quite reliable and operate with changing pressures.----------Try adjusting the low speed jets ----------------If it is idling and stumbles then open them both up 1/8 th turn and try again.---------Do you have spark that will jump a gap of 3/8" on all 4 cylinders ??

slorole
10-18-2011, 01:39 PM
had to go check but yes it has a good blue arc 3/8" on all 4. after setting the jets 1 1/2 from lightly seated. put it in gear and it dies. backed off 1/8 turn
multiple attempts till the point there's no tension on the jet spring still dies.

racerone
10-18-2011, 01:46 PM
You have good compression !---------Good spark !!!!!----------------My bet is a fuel issue.-----------Blockage in the carburetors.

guyjg
10-18-2011, 01:54 PM
Might just be a hard varnish blockage in the engine's fuel line connector since the carbs have been done twice.

slorole
10-18-2011, 02:00 PM
only place I can see that being is under one of the welch caps, would have to order new caps before pulling them.

racerone
10-18-2011, 04:40 PM
Do you by any chance know why it sat unused for 15 years ??----------------Any chance mice or other critters got in the motor somehow ???--------You also MUST install a new waterpump impeller if it sat that long !!

slorole
10-18-2011, 04:58 PM
as of this year the man I got it from is 96 years old, it is mounted on a 1978 15' venture 1550. last time he was going to use it was to take his grand son fishing. but that trip never happened. his grand son ended up in jail and the boat was put in the barn and never used again.
it was covered with dirtdobber nest, but nothing could get internal.
I know I didn't say so but the water pump was 2nd thing changed.

haventaclue
10-18-2011, 05:14 PM
Did you do the fuel pump diaphragms while you were doing the gaskets?

slorole
10-18-2011, 05:37 PM
no, I have a fuel pump kit ordered but I have 2 psi at wot.

slorole
10-22-2011, 10:33 AM
well I rebuilt the fuel pump and still the same old issues.
I went and had a talk to the guy I got the boat from, he stated that he never had any thing replaced on the motor and he bought it new.
so I guess I'm starting from the step one again.

haventaclue
10-22-2011, 12:16 PM
Did you move anything on the timing?If you did,did you set it with the engine running in water and in gear?
Still sounds like a fuel issue.When setting the idle did you have it under load? If you want to check the reeds,pull the carbs,you'll see the petals,very gently push each petal to be sure they aren't sticking.
Crankcase seal, top or bottom or both?

slorole
10-22-2011, 01:54 PM
at this point I got it going into gear and not dieing at about 1100 rpm but I need it under 1000 but any thing under 1100 stalls and dies. that's why I believe
the reeds are weak or sticking.
and yes sir. it's in gear under load in a tank.

haventaclue
10-22-2011, 04:52 PM
Sorry but I had to ask,clutching at straws.:).It's rare for the reeds to go and means splitting the case to inspect.Are the restrictors in place? Worth a look before splitting the crankcase

guyjg
10-22-2011, 06:07 PM
...has been setting for about 15 years. Replacing all gaskets, replaced all fuel lines. How about the connector on the engine?

I still think the fuel connector is plugged. Fuel varnish can get hard as dried paint. Somebody had the same issue and tried changing everything last summer on a boat that sat a few years and a boat shop found the connector on the engine plugged. I sure as hell would rather clean a connector before I crack open a case.

slorole
10-22-2011, 07:50 PM
don't Apologize!! I've had a lot of help from you, and could have missed something and your clutching at straws could be the answer.

slorole
10-22-2011, 07:56 PM
How about the connector on the engine?

I still think the fuel connector is plugged. Fuel varnish can get hard as dried paint. Somebody had the same issue and tried changing everything last summer on a boat that sat a few years and a boat shop found the connector on the engine plugged. I sure as hell would rather clean a connector before I crack open a case. I have made an attempt at cleaning the connectors on both carb's including the fuel line "T" every thing seems to be clear.

slorole
10-22-2011, 08:01 PM
I just came back off the water, as long as I go into gear and give some throttle it will stay running, the hole shot is great.

guyjg
10-22-2011, 08:04 PM
I'm talking about the main fuel female receptacle on the engine that the external fuel tank line w/squeeze bulb attaches w/male probe connector.

slorole
10-22-2011, 08:15 PM
I'm talking about the main fuel female receptacle on the engine that the external fuel tank line w/squeeze bulb attaches w/male probe connector.Ok, that's something I haven't checked. ill give it a shot at day brake.

slorole
10-23-2011, 10:12 AM
(good morning) guyjg I broke down the receptacles on the engine and the tank line clean them, only thing that looked bad was an O-ring on the
engine side so I replaced it, put it back in water tank but it didn't change any thing. but it was worth a shot.

guyjg
10-23-2011, 12:50 PM
...I believe the reeds are weak or sticking. If they are sticking a good spray Seafoam cleaning with engine running may do the trick. Keep the RPMs up to 1500 and spray it into the carbs alternating 10 second sprays in each for a minute or two. Shut it off and let it soak for 30 minutes. Repeat several times. It will smoke alot but won't harm it one bit. It will clean out all the varnish and carbon from the engine. It just may do the trick.

racerone
10-23-2011, 01:19 PM
I doubt that reeds are sticking.-------Never run accross that on any motor.

timebandit
10-23-2011, 01:30 PM
What I would do here is remove the plug wires one at a time (carefully) with the motor idling to see what cylinders are not hitting. Use a plastic pliers and try not to shocked to death.
Timing issues will this problem. The pickup timing needs to be exactly right. You are doing this with the timing gun, right?.

One other thing that will cause problems is the bleed restrictors in the intake ports. They are plastc orfices and thay fall out. This is inside the transfer port side cover. Not the exhaust plate.

slorole
10-23-2011, 03:26 PM
What I would do here is remove the plug wires one at a time (carefully) with the motor idling to see what cylinders are not hitting. Use a plastic pliers and try not to shocked to death.
Timing issues will this problem. The pickup timing needs to be exactly right. You are doing this with the timing gun, right?.Im getting plenty fire over 3/8" on spark tester have new plugs (could be one is week) Ill change them again. I am using a timing light.


One other thing that will cause problems is the bleed restrictors in the intake ports. They are plastc orfices and thay fall out. This is inside the transfer port side cover. Not the exhaust plate.I'll have to look over the book to see what it takes to check this out.

timebandit
10-23-2011, 06:41 PM
Im getting plenty fire over 3/8" on spark tester have new plugs (could be one is week) Ill change them again. I am using a timing light.

I'll have to look over the book to see what it takes to check this out.

I am trying to isolate any powerhead problems with air leaks or worn out cylinders.

slorole
10-23-2011, 07:03 PM
sorry, had a Dr. visit. I understand what your getting at now. I was gonna pull the plug wires as you suggested but at the moment it's raining and that's the last thing I won't to do on wet ground LOL.

racerone
10-23-2011, 07:09 PM
If bleed restricters are missing it is a " huge hole " so to speak to the cylinder below.---------------Use a tooth pick as a probe to see if any are missing.-----------I install 8-32 stainless setscrews ( 0.035" hole ) on rebuilds, never fall out again.

slorole
10-23-2011, 08:42 PM
Let's hope there not gone cause I'm only finding the Transfer Port Cover Gasket and nothing on the bleed restrictors.

slorole
10-23-2011, 09:07 PM
If bleed restricters are missing it is a " huge hole " so to speak to the cylinder below.---------------Use a tooth pick as a probe to see if any are missing.-----------I install 8-32 stainless setscrews ( 0.035" hole ) on rebuilds, never fall out again.I was just reading another post you mentioned this on, so correct me if I'm wrong. are you saying to just plug the bleed restrictor holes?

racerone
10-23-2011, 10:12 PM
NO-I install much better bleed restrictors.

slorole
10-23-2011, 10:37 PM
NO-I install much better bleed restrictors.Ok I understand now I misread your post. I'll see if local dealer has any gaskets tomorrow. Thanks

slorole
10-24-2011, 10:59 AM
no luck finding the gaskets locally. but I'm no stranger to making gaskets but dose anyone know the thickness of the Transfer Port Cover Gasket?

slorole
11-06-2011, 01:15 PM
after wating 2 weeks for gasket to come in, I install 8-32 stainless set screws with 0.035" holes for bleeders but made no difference. still stalls out when put in gear.but just for the record it was 2 out of 3 bleed restrictors gone.

racerone
11-06-2011, 01:52 PM
The additional load of a prop turning in water should slow an idling motor down by 50 -100 RPM.-----------Yours stalls so it is not producing the correct power to keep running.-----------Perhaps it is idling to slow initially.-----------Perhaps the carburetors are not " clean "---------------seen many tales of people on these sites taking carburetors apart 3 / 4 times before they finally " get it right "-----With the motor in nuetral and idling what happens when you turn in ( from 1-1/2 turn out from seated ) the slow speed mixture screws ( one at a time ) and what happens when you turn them out ???

slorole
11-06-2011, 02:04 PM
The additional load of a prop turning in water should slow an idling motor down by 50 -100 RPM.-----------Yours stalls so it is not producing the correct power to keep running.-----------Perhaps it is idling to slow initially.-----------Perhaps the carburetors are not " clean "---------------seen many tales of people on these sites taking carburetors apart 3 / 4 times before they finally " get it right "-----With the motor in nuetral and idling what happens when you turn in ( from 1-1/2 turn out from seated ) the slow speed mixture screws ( one at a time ) and what happens when you turn them out ??? well can't hurt to clean carb's again, I remember a heated solution we used to clean auto carb's long ago just can't remember the name but it worked well, strip the carbs and place it in the vat.

guyjg
11-06-2011, 02:26 PM
Laquer thinner does a number on old gas varnished fuel passages. I use it on all metal carb parts in an clean paint style can. Just use it outdoors since it is very dangerous...it will kill you if inhaled or it ignites.

slorole
11-06-2011, 02:32 PM
Laquer thinner does a number on old gas varnished fuel passages. I use it on all metal carb parts in an clean paint style can. Just use it outdoors since it is very dangerous...it will kill you if inhaled or it ignites.good choise and advice I'll give that a try.

slorole
03-14-2012, 08:21 PM
Well guys after getting over surgery in both shoulders I’m back on my boat again. And after following all the good advice to no avail. I thought I had burned out my water pump when it stopped putting out water. So I pulled the foot to
find milky oil coming from the exhaust tube. Water pump was still good. So ether a blown head gasket or cracked head.
Either way it’s not good.
Just don’t see how it’s still got good compression, 130 to 135 all four cylinders.
But it may be that was what was causing all my problems to begin with.

racerone
03-14-2012, 11:55 PM
There is no " head gasket " on that motor.-------Only a water jacket cover gasket.-------Milky oil in the exhaust is a common occurrance in a 2 stroke motor and very normal.

fastjeff
03-15-2012, 08:59 AM
The distributor Mercs have a complicated advance mechanism. When the throttle is opened, the distributor goes from full retard to max THEN the carbs start opening. If you watch carefully, as you open the throttle, you'll see the distributor STOP at full advance while the mechanism contines to rotate, which opes the carbs.

What happens on motors that have sat around for a long time is that the grease in the mechanism dries out and freezes the mechanism, and when THAT happens, the carbs either don't open at all, or only partially.

So, here's what to do:

1. Make sure this mechanism is free. If not, remove it, dissaemble it, clean out the old grease, and reassemble with new grease. That's the only cure.

2. Study carefully the adjustment stops on the plate in front: Note the Max Spark Advances, and the Max Throttle Stop (carbs fully open). Be sure the carbs don't (or barely) start to open before the distributor reaches FULL spark advance. If not, welcome to Bog City.

3. Time it with a light. The best and safest way to do this it to remove the top carb's throttle cam arm (one screw). That way you can hold her wide open (about 3 grand) and get the timing perfect.

Do all this and she'll run great!

Jeff

haventaclue
03-15-2012, 10:01 AM
I'm thinking it's coil per cyl on a '78.Could be wrong.Back to clutching at straws,Is there by any chance a straight line and three dots on the flywheel? The straight line is the set mark and the three dots the timing mark when cranking.But that's on older 800's.Maybe the timing pointer is out of sync. There is a bit about it in the Seloc manual

fastjeff
03-16-2012, 07:34 AM
You are correct; no distributor on that one. To time it, though, the best way remains removing the top carb's throttle lever (one screw) and holding the throttle open. The flywheel has degrees marked on it for timing. I think 23 ' max is what's called for.

Jeff

slorole
03-16-2012, 04:14 PM
I'm thinking it's coil per cyl on a '78.Could be wrong.Back to clutching at straws,Is there by any chance a straight line and three dots on the flywheel? The straight line is the set mark and the three dots the timing mark when cranking.But that's on older 800's.Maybe the timing pointer is out of sync. There is a bit about it in the Seloc manual
Yes havevtaclue it is coil per cylinder and no there is no 3 dotís only lines and degree markings.
Think I will start from scratch tomorrow and check the Timing marker and go from there.
If I canít find it this timeÖÖÖ. I guess Iíll put it in the shop. (Lord Knows I hate That) may not get it back this summer. LOL.
Let yall know what happens.

fastjeff
03-17-2012, 07:49 AM
Don't give up until you see how she's timed. Do it the way I explained above--easy to do--and that'll be out of the way. If it still runs badly, then you'll need to look at other things.

Jeff

slorole
03-18-2012, 02:08 PM
well after looking very close... it looks as the ring bolts have been removed from the flywheel, now I have figure out it they were put back correct.
Talked to Mr. leon he doesn't recall ever having the motor worked on but broken paint on all the ring bolts tells me it has.

slorole
04-08-2012, 09:12 PM
Well guys this is just an update. I ordered a new powerhead (new old stock) now I’m fishing again and runs great.
For the heck of it I split the old powerhead and found some reeds stuck closed and some had gaps a good 1/16 or better but I’m guessing that was the cause.
Now I think I’ll completely rebuild it while I can still get parts. But I would like to tell everyone who tried to help,,,,,,,Thank you.