Before tearing apart carbs...71 merc 800 not starting

[rtpassini]

a lot of you have tried helping me but still no go.
good spark, good compression, but just wont fire over. tried squirting fuel into carbs, but didnt do anything.

a shop told me the carbs are just probably really gunked up and i should take them apart.

do any of you think this could be it? ive never done carb work before...so if i can avoid it, i would like to. also, i read about the sheared flywheel key. how do i check this?

 

[Moody Blue]

Re: Before tearing apart carbs...71 merc 800 not starting

Have you performed a complete sync and link? A very good tutorial in the FAQ section. That would be my next approach.

Verify the TDC of #1 cyl corresponds with the flywheel TDC timing mark AND the TDC mark on the distributor gear.

Ideally you should use a dial gauge but can get by with a vernier caliper. If you don't have either of those, you can be pretty close by just using a pencil and inserting it into the cyl. SLOWLY turn the flywheel till the piston reaches TDC. The piston will push the pencil out as it travels up the cyl. Motion will be barely detectable during the last few degrees of rotation so be very aware. Try it several times to get a feel for the actual TDC.

Now that you have determined TDC of the piston as accurately as possible, check that the timing marks on the flywheel (3 small white dots on the edge of the flywheel) align with the TDC mark on the timing decal. Also check that the distrib timing gear is aligned with the TDC mark on the distrib housing. All three must align at TDC (piston, flywheel, distrib timing gear).

Also, are you absolutely certain that the plug wires are installed correctly and not crossed between the distrib and plugs? Strange that it will not fire if you squirt fuel directly into the carb throats. Make sure you open the throttle plates before squirting in the fuel.

 

[rtpassini]

Re: Before tearing apart carbs...71 merc 800 not starting

i havent opened the throttle plates to squirt them in. ill try that tomorrow.

im not 100 percent sure the wires are correct. but i would think it would at least sputter a litle bit.

also, wheres the distributor timing gear/mark? (just so im not looking forever)

ill be trying all this stuff out tomorrow hopefully.
moody, you have been one of my go to guys with this stupid motor. i really appreciate it.

 

[rtpassini]

Re: Before tearing apart carbs...71 merc 800 not starting

i checked the timing and its on point.

tried squirting fuel into the carbs a few times sputtered once but then stopped even though i was holding the key. kept trying, but the battery was dieing.

when i went WOT to spray the gas in, gas starting dripping out of the carb...normal?

THEN i was doing stuff with the wires and pulled them off the cap, well, the wires ripped out and i couldnt get them back in. im pissed.

if anyone has this motor, could you label your plugs and the spots on the dizzy so im 100 percent sure i have them right. although now i have to order a new cap and wires....

 

[Chris1956]

Re: Before tearing apart carbs...71 merc 800 not starting

The dissy wires screw into the cap. You can buy replacemmnts for about $6 ea. at oldmercs.com

Set the top cylinder to TDC with a screwdriver. Observe the timing mark on teh flywheel and cowl support. it should read about TDC. Remove the cover on the dissy pully (5/16 bolt). The cast arrow should point at the dots on the flywheel. If this all checks, the motor should start. Spray iboth throats with 50::1 fuel, and close the chhoke shutters and it should run for 5 sec. if so, clean the carbs and rebuild with new gaskets and inlet needle and seat.
Pick up a service manual.

 

[rtpassini]

Re: Before tearing apart carbs...71 merc 800 not starting

they other guy thats always helping me! thanks!

the arrow does point at the flywheel and everything checks out.

like i said, i sprayed both in, shut the choke plates, with the warm up lever up. it didnt really do anything except one time, it sputtered for 1 second and then didnt do anything. but now i have to buy new dizzy wire screws like you said. is that what i need? heres a pic.

also, i have a manual, but its not very helpful (probably because its not the FACTORY service manual)

 

[Moody Blue]

Re: Before tearing apart carbs...71 merc 800 not starting

Ouch, too bad about the plug wires. You don't want to buy a new cap if you don't have to. Will run you $140 for new.

You should be able to use a pair of needle nose pliers and unscrew the plug wire ends from the cap. If careful, you may be able to crimp them back onto the plug wires.

One of your problems may be the battery. I recall in one of your ealrlier posts that you were having troubles with the battery. The ignition system NEEDs 12V to operate properly. You should be able to crank that motor over for a LONG time before the battery dies. I used my battery alot while playing around installing and setting up the power trim and for performing the sync and link procedure. I still had lots of juice left to crank the motor over repeatedly.

I've got photos of the distrib showing plug #'s that I'll post tomorrow.

 

[rtpassini]

Re: Before tearing apart carbs...71 merc 800 not starting

i was actually just out there trying to recrimp those things. hopefully i have them fixed.

i got the battery charging right now so itll be ready to go for tomorrow.

thank for the pictures. ill try reporting back on what happens.