1965 merc 900 Wont start

[mom987mercury]

Just purchased this motor,was running 402 merc.The 90 hp merc has fire to all 6 plugs,carbs have been cleaned(not adjusted).Fuel is going to and through carbs in to motor.I checked and the rotor button is pointing to #1 cylinder with cylinder at tdc,when i turn over the motor it will only backfire out the exhaust.I am lost...Any info would be great,Thanks....

 

[OBJ]

Re: 1965 merc 900 Wont start

mom....if your backfiring through the exhaust, chances are a couple wires are crossed and the wrong spark is going to the wrong cylinder. Check your wireing to the switch pack and spark plug wires. If unsure, index the flywheel for each cylinder and use a timing light to be sure the cylinders are firing at the right time.

 

[emckelvy]

Re: 1965 merc 900 Wont start

This motor is likely old enough not to have electronic ign. There are 2 firing order patterns on the old points style Inline 6 distributor caps. <br /><br />For this motor you want the pattern that does NOT say "76 cu in". If someone mistakely put the wires in the "76 cu in" slot it would backfire and likely wouldn't run at all.<br /><br />The wires screw into the cap so be careful with them, if you pull rather than unscrew it'll ruin them.<br /><br />At least that's what I remember, haven't messed with one of those ign's since I sold my 100HP back in the 80's!

 

[mom987mercury]

Re: 1965 merc 900 Wont start

I should add that the firing order is written on the cylinder head but the rotor button does have two firing points on it 90 degrees apart.Could this have a link to the problem??

 

[Clams Canino]

Re: 1965 merc 900 Wont start

Assuming the choke is working and being used propery...... and the plug wires are all correct.<br /><br />You have a duel point distributor. The way to set those points is to set one set for 90 degrees of dwell (closure) and then set the second set to open EXACTLY 60 degrees after the 1st set opens - regardless of dwell. <br /><br />You probable know that cap has two buttons, one center and one on the side. If you pull the cap, you can then remove the entire breaker assembly with 4 bolts. Then GENTLY pry the rotor off with 2 screwdrivers near the shaft, prying on the flange WILL break the rotor. After that you can remove the cover and get to the points, clean them and set them as dscribed, make a little degree wheel on cardboard. Also make sure the right set of points is firing the right coil, That will do it too.<br /><br />Set max advance for 34 degrees once it's all together.<br /><br />Set up correctly, you are gonna like this motor a lot.<br /><br />-W

 

[NEECAPRS]

Re: 1965 merc 900 Wont start

Mom: If you need more help setting the points, there was a very detailed thread here last fall. I can help you find it if necessary.<br />There are as many as three sets of cylinder numbers on your distibutor cap. Two would be molded-in. The third would be printed-on numbers, surrounded by square boxes. For your 90 HP, 90 CI, use the outer row of molded-in numbers. They're placed between the cylinder poles.<br />Good luck!!

 

[NEECAPRS]

Re: 1965 merc 900 Wont start

Mom: Just in case you need the point set-up data and I don't see your request, it's now on page 22, Sept. 11, 2003, request from "martyt" about 1965, Merc 1000, Won't start.<br />It's just like Clams says, just a lot more elaborate.

 

[mom987mercury]

Re: 1965 merc 900 Wont start

Yes you are right ,there is alot of numbers on that cap and there is also a 1 on the inside of it indicating that to be number one plug.But this does not match any of the other mumbers.Yes i would appreciate that information on the points setting.I changed the wires since my first post and now it almost wants to start.I guess it must be another set of numbers...Thanks ....Tom.H...

 

[Clams Canino]

Re: 1965 merc 900 Wont start

I just bumped the 65 1000 thread to the front page. Good long explainations there. (same basic motor)<br /><br />-W

 

[mom987mercury]

Re: 1965 merc 900 Wont start

Well,i just dont know anymore,i have tried all the possible wire positions on the distributor cap with no success.Spark is bright blue in all culinders and large.I am begining to think that maybe the distributor has slipped on the flywheel belt and is possibly causing this heart break.I cant seem to find any marks on the fly wheel and only a small hole in the distributor pully.Does anybody have any info on how to set the timing on this old doll??.I am having a hard time trying to find some litterature on this motor and it is totally different from my 402 merc (not to mention three times as high)Thanks...

 

[Clams Canino]

Re: 1965 merc 900 Wont start

Mercury makes a 1965 and prior manual, it covers timing and syncronization of the duel point outboards very well. I have a 1961 Merc 800 with the same setup.<br /><br />You should at least have a spot on the side of the flywheel with some punch mark(s) to indicate the #1 cylinder at top dead center. <br /><br />My manual is packed as we are moving soon. Let me get back to you tomorrow.<br /><br />-W

 

[Clams Canino]

Re: 1965 merc 900 Wont start

Print this linked pic out for openers. Make sure you full size it 1st.<br /> web page <br /><br />-W

 

[emckelvy]

Re: 1965 merc 900 Wont start

Here's some good ign links that "Kirk out East" posted at Old John's Merc board:<br /><br /> http://www.maxrules.com/oldmercs/timing/41.pdf <br /> http://www.maxrules.com/oldmercs/timing/42.pdf <br /> http://www.maxrules.com/oldmercs/timing/43.pdf <br /> http://www.maxrules.com/oldmercs/timing/44.pdf <br /><br />If you look at the diagram in the first page it shows all the different firing order patterns. Missed a few I guess, must have been another senior moment!<br /><br />It's very possible the belt may have been installed out-of-whack, it's pretty easy to get it realigned again IAW the instructions and diagram on the first page.

 

[Clams Canino]

Re: 1965 merc 900 Wont start

Those PDF's are great! Those are from the manual I mentioned.<br /><br />Note that the cover has to be removed from the pulley to check the marks. Also the *outer* ring of numbers on the cap is the correct one for 76 and 89 CI inlines.<br /><br />Also that whole thing with the .222 piston guage sets up a 34 degree advance. Just find TDC and then degree out the flywheel to make a 34 degree advance mark. Time max advance stop accordingly.<br /><br />The whole part with the throttle pickup plate adjustment translates to: "As the advance just approaches TDC the 1st pickup plate should begin to hit the carb cluster. After max advance is reached, the second plate should hit and the rest of the throttle movement opens the carbs.<br /><br />When I set up my 800 it took the better part of a day. I hade to make my own degree wheels to set up the points, draw marks on the fly wheel etc etc. It was worth it though. I ran that thing HARD for a whole summer and never had to take the covers off once.<br /><br />-W

 

[mom987mercury]

Re: 1965 merc 900 Wont start

Thanks guys,I am going to head out now and have another go at it.I printed out those pages on the timing setting and will do a flywheel check.this should'nt take too long .I will post my results shortly.I am greatfull for everyones assistance...Tom...

 

[Clams Canino]

Re: 1965 merc 900 Wont start

Coil #1 is to the rear and coil #2 is up front. The brown wire goes to #2 the white to #1.<br /><br />-W

 

[mom987mercury]

Re: 1965 merc 900 Wont start

Ok great news,it runs,after changing the wires to the set of numbers on the distributor cap in blocks ,adding a large amount of fuel to carbs and using a stronger battery it took right off.have alot of blue smoke and some bursts of black smoke.Carburators may need some adjusting,after all,we just ran a motor that has not run for over five years,just been standing in a shop in the corner forgotten about until i purchased it for $100.00,it sound like a good deal to me.Thanks clams ,and every one else for the helping hand on this one,I needed it,Now off to the carbs.

 

[NEECAPRS]

Re: 1965 merc 900 Wont start

Mom, Sorry I give you the wrong number set earlier. I assume you're talking about the printed numbers in printed blocks. <br />According to my Master Service Manual your motor that uses those numbers should be a 950SS or an 1100SS. I wonder if it's either of those with a later year 900 cowl or a 900 from the late 60's. The manual doesn't speak of a 900 made in 1965 or earlier!!

 

[mom987mercury]

Re: 1965 merc 900 Wont start

Well now i dont know,it could be either of those engines that you mentioned.All i know is what those guy's told me and remember,that engine has been sitting in the back corner of the shop for five years and was there for the previous shop owners,so they really had no knowledge of the motor at all.They just wanted to clear out the old stock.The serial number is 1755391 and the firing order 145236.Please let me know what you come up with...

 

[Clams Canino]

Re: 1965 merc 900 Wont start

Its not an SS. It's the plain vanilla Merc 1000 strangled a bit with small carbs.<br /><br />-W