1970's merc 400 outboard troubles... help please

[jligori]

Hey all, long time lurker, first time poster.

I have a early 70's Merc 400 40 horse outboard. Its on an older 14 foot fiberglass boat. I picked it up late last season, and did some of the basics too it.
Totally gutted and rebuilt the carb and went to a high altitude jet (boat spends its life above 6500 ft and its not unusual for it to go up to 9500 ft) tear down was NOS kit, with new gaskets, needles etc.

Definitely ran better after that but still didn't seem 100%. I bought a "tiny tach" for it, engine only revs to about 2200, not the service manual recommended 4800 to 5200. I am thinking I'll try a fuel pump kit next, and maybe new hoses and bulb. Any other ideas to get it rev back up to the 4800 mark? I have heard that stators and switch boxes could be the issue, but i hate to throw expensive parts at them if they aren't going to help. Any ideas?

First thing this season, I tore down the lower unit and put in a new water pump impeller, gaskets, and top housing. Bottom hosing looked worn, but didn't have one on hand and didn't want to wait on ordering one as it didn't look too bad. Got it all put back together, but now the engine won't go into neutral or reverse, its all forward, all the time. Must be I didn't get that shift linkage lined up right, it was a bear too. Any insight how to go about getting it back to "normal" I would like reverse and neutral back...

thanks!

 

[merc850]

This is how I do it in about 60 sec.: Turn the LU shift shaft by hand counter-clockwise until it
stops, then with Vise Grips tight on the bottom of the shaft turn it a
few more degrees CCW until it clicks into a stop, this
should be neutral - check by turning propshaft --
prop should spin freely.
Put control in N grease the driveshaft splines and go ahead and attach LU to driveshaft housing some turning of the flywheel will help the DS splines align.
Do not shift into reverse unless you turn the prop at the same time.

 

[93ultra]

I sometimes take my boat to a lake in the mountains that's at about 6000' and what I do is change the prop size by two sizes down in diameter. It was suggested to me by more than one mechanic so I decided to give it a try and it worked well. Maybe some others here have other ideas but it works for me.

 

[93ultra]

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[jligori]

thanks guys, I will try to get the LU on right this weekend when I have some time. I have the service manual for it, and there were some other tips in there that I missed the first time around. I am already running an 11 pitch prop and have a beat up 10 for a spare.

What about the top end? I got a fuel pump kit ordered and will redo all the fuel lines as well. I have a second switch box that I could try and swap in. I got it from a parts lot and the guy "said it worked". I also found in the manual how i can test the low/high speed in the stator with an ohm meter but I think I need the DVA meter to test the actual switch box itself. If I do jump into a new stator, will one of the universal pullers work, I am having a hard time finding a merc one. And what about any tips for holding the flywheel to break the nut free? I am thinking along the lines of a ratchet strap?

 

[jligori]

Got the lower end off and put back on correctly. Now have forward, reverse and neutral again. Not really sure how/what we did different but all seems good to go now. Putting it in neutral was probably the big trick, thanks Merc850.

Still have an issue with top end, and general rough idle/running. Stator and trigger all test out good, with an ohm meter. I can't test the power pack but like I said the engine does run (and seem to like to run better when its cold). The coil tested fine on the primary side, but I only showed an open circuit on the high voltage discharge side, where the manual says there should be some resistance. Also spark seems weaker that what I would think normal would be, and there was also a fair amount of goo, that had leaked from the coil and hardened on the plug wire and plug boot. So I think its time to try and replace the coil, but as many of you are probably aware, its a no longer available part. I don't really want to buy on off ebay or something and have it work for a while, or be bad upon arrival.

Does anyone know if there is another different coil that I could swap in? OR does anyone rebuild coils? thanks all.