Johnson 75 hp Slow to pick up power

F

fromtheriviera

Cadet
Joined
May 27, 2009
Messages
23
Re: Johnson 75 hp Slow to pick up power

Tachometer: I think I would rather mount a permanent lowest budget tachometer because I live in france want to avoid shipping charges from US or UK. I have located the 3 pin wires ready to adapt. .

Can you recommend a standard low budget US model / make that would suit my motor then I will try to see if I can buy locally in a marine merchant. Thanks chinewalker for your comments I will keep in mind that the motor is rare. That all the more reason I would like to invest a bit in it to keep it running for a few more years then.

Water impeller change: I guess this means having it serviced then ? I have changed the lower unit oil but was hoping to avoid servicing the engine this year. In south of france everything is 400% more expensive and the mechanics are not friendly in the least. I will ask for a quote.

Solenoid Primer: Will leave it like this as don't use the boat in winter and here the temperature is prety mild all year round.

Missing housing:
I am looking for second hand exhaust housing as my motor did not have these parts when I bought it.

http://www.boats.net/parts/search/BRP/JOHNSON/1988/J75ECCA 1988/MIDSECTION/parts.html

44 0206006
COVER, Exhaust housing, rear
45 0330373
COVER, Exhaust housing, front
46 0320211
EXHAUST HOUSING, Outer
50 0314024
SEAL, Outer housing
 
jtexas

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: Johnson 75 hp Slow to pick up power

Teleflex Marine would probably be the preferred economy model of tachometer, it's what I use. You can spend more, but I always try to avoid it.

Water pump service is a routine do-it-yourself procedure:
1. remove prop
2. disconnect shift linkage under the bottom carb -- it's a 7/16" hex-head screw accessible from the port side.
3. remove the trim tab (scribe a mark across the edge so you can get it back like it was).
4. remove the retaining bolt up in the trim tab cavity.
5. remove the other retaining bolt from the bottom side of the antiventilation plate.
6. remove the four retaining bolts from the perimeter, just above the antiventilation plate.
7. pull the lower unit off.
8. the shift rod height is adjusted by screwing it in or out, so don't twist it, else it won't fit when you put it back.
9. Four hex-head screws hold the water pump housing down.
10. Slide the old impeller off the drive shaft.
11. Slide the new one on. Slip the woodruff key in place just before the impeller covers the keyway.
12. Put a new housing gasket in place.
13. Grease the inside of the housing (trailer axle grease is fine), and shove it down onto the impeller while turning the driveshaft clockwise with your hand. Don't use any kind of tool on the driveshaft splines -- that is an expensive precision machined part.

On reassembly:
* put molly lube on the drive shaft splines (but not on top, there's not enough clearance).
* the rubber o-ring just below the drive shaft splines -- don't forget that.
* put omc gasket sealant (or your favorite anti-sieze) on the retaining bolts -- or else corrosion will freeze them in place.
* use 3m #847 or permatex #2 on the joint between midsection & lower unit. www.ishopmarine.com has 847 -- permatex is messier and harder clean next time around. Optionally, you can just leave it bare -- it does not have to hold water.
 
F

fromtheriviera

Cadet
Joined
May 27, 2009
Messages
23
Re: Johnson 75 hp Slow to pick up power

http://picasaweb.google.com/106298816060283696541/20100812?authkey=Gv1sRgCJ-FtfKom5mgAw#

Hello, see above link, I have made the carb throttle alignment settings you recommended. Have not tunred the motor on yet to hear the difference as my neighbours are a bit of a pain. I understand what this will do so expect good results.

Teleflex White Premier Pro Instrument - Tachometer (7000 rpm) looks nice. Is 7000 enough then based on what you said that I should be at 6000 or less at WOT ?

Let me know about the spark plug question. Are they factory set if I get the correct model or do I have to still set them at 0.75mm ? I will check when I have my spark check tool.
 
F

fromtheriviera

Cadet
Joined
May 27, 2009
Messages
23
Re: Johnson 75 hp Slow to pick up power

Hello,
I checked the overtemp warning horn and the circuit is ok as I checked it with a tester , but my warning horn was not connected to the correct wire on my dashboard and is alos dead. Makes a tinny noise that I would not be able to hear if overheating. So will buy a new one today.

So whats left.
Thachometer, Water pump, spark plug gap, Seafoam cylinder cleaner. (I need to find a french equivalent as seafoam does not exist here.) If I understand correctly I can ask for a marine motor treatment to de-carbonise ?

A question about dropping the lower unit. Do I have to take the carbs off before I can get to the hex screw on the port side below the lower carburator ?

Will advise when I have more news.
 
jtexas

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: Johnson 75 hp Slow to pick up power

That horn does sound kind of whiney, like a spoiled child.......

7k on the tach will be plenty.

Check the spark plug gap before installing.

Shift rod disconnect: carb removal not necessary. Disconnecting the fuel supply hose from the fuel pump and shifting it out of the way will allow better access if needed. It's a good opportunity to clean the screen filter on the front of the pump. Short socket extension will help. A bit of grease inside the socket will keep it from falling. Try not to drop the lockwasher but if you do, don't bother trying to retrieve it (not worth the trouble -- don't ask me how I know).

A lot of engine cleaners on the market are ok for automobiles and other four stroke engines, but I wouldn't run them in my outboard. Look specifically for something compatible with 2-stroke motors. Seafoam is about 1/2 pale oil, about 10% isopropyl alcohol and the rest naphtha. BRP Engine Tuner, Mercury Marine Quickleen, Yamaha Ring Free are all suitable, or something similar.
 
F

fromtheriviera

Cadet
Joined
May 27, 2009
Messages
23
Re: Johnson 75 hp Slow to pick up power

Thanks for these other names. I sent a mail to customersupport at seafoam and they conformed that can't buy the stuff in France.

I will see if I can find any of these other 2 stroke products or similar here.
Will take a few days break from the boat scene as it been raining so thanks for all your advice so far and will be in touch as soon as I have bought all the parts and start mounting them. Then will take the boat out to sea and will video the results.

Really appreciate your help ! And won't start the water impeller change until I have all the new parts like housing gasket , gasket sealant etc... I just hope I don't damage anything when I do this as I have never tried.

Speak to you soon .
 
jtexas

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: Johnson 75 hp Slow to pick up power

yes, I made a mistake...the correct tachometer setting is 6p.

sorry about the confusion.
 
jtexas

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: Johnson 75 hp Slow to pick up power

yes, I was mistaken before -- 6p is the correct setting, not 12p.

The alternator has 12 poles, and sends 6 pulses to the tachometer. I got confused about poles and pulses....sorry bout that.

?70 sounds about right.
 
F

fromtheriviera

Cadet
Joined
May 27, 2009
Messages
23
Re: Johnson 75 hp Slow to pick up power

Great , thanks. You always bring good news.

During the night I realised what is causing extra weight. I forgot to mention that I have a 4 hp emergency motor at the rear left of the boat in the up position. It does not drag in the water but is most probably extra weight I could get rid of. I will see if I can fix it behind the front seats until the day I need to use it.
 
F

fromtheriviera

Cadet
Joined
May 27, 2009
Messages
23
Re: Johnson 75 hp Slow to pick up power

This weekend I have bought an old J75ELCRD 1984 for 200 ? . It had a piston problem and did not start anymore so I bought it for spare parts to put on my other engine.

I have managed to take off the elecrical components.
Carbs, Starter , solenoid, petrol pump/filter and I an now trying to take the
base off to see how easy it is to change a waterpump myself next time.

It had a prop that looks like 13 5/8 x 17 . Difficult to read as someone painted it. I have removed it to try on my other engine as soon as I get my boat back from servicing the water pump.
I will mount it with the tachometer and will see the RPM at WOT. Will report on outcome soon.

Anyway , back to the taking off the base.

1. remove prop DONE
2. disconnect shift linkage under the bottom carb -- it's a 7/16" hex-head screw accessible from the port side. DONE

Will continue tomorrow.

3. remove the trim tab (scribe a mark across the edge so you can get it back like it was). NOT DONE YET
4. remove the retaining bolt up in the trim tab cavity. NOT DONE YET
5. remove the other retaining bolt from the bottom side of the antiventilation plate. NOT DONE YET
6. remove the four retaining bolts from the perimeter, just above the antiventilation plate. DONE
 
F

fromtheriviera

Cadet
Joined
May 27, 2009
Messages
23
Re: Johnson 75 hp Slow to pick up power

I have managed to get the base off and I can now access the water pump.

Will report on Propeller progress when i get my boat back from the mecanic.

I will try the 13 3/8 x 19 and report on the RPM.

Will start a new thread concerning the other engine i Just bought cause I want to remove the hydrolic power trim to see if I can put them on this engine then I want to start rebuilding the brocken piston on E75ELCRD.

Would appreciate any advise you can give me on that thread .

http://forums.iboats.com/showthread.php?p=2910345#post2910345
 
You must log in or register to reply here.
Top