1978 Evinrude 70HP- Trouble starting/idling/bogging under load

evinrude2323

Seaman
Joined
Nov 11, 2024
Messages
52
Slide rubber boot back to expose the metal connecter.-----Turn key to on.----Touch metal connecter to ground.----Horn should sound.----And no need to open throttle to do a compression test on that simple motor.
I’m starting to think it was a combo of the previous owner closing the choke flaps, pouring too much oil in his gas mix, then dumping an entire bottle of seafoam in as well to clean the carbs. I’ve since got it attached to a new gas tank and it’s been great since I opened the carbs. And again the alarm works just tested it!
 

ct1762@gmail.com

Master Chief Petty Officer
Joined
Jan 17, 2019
Messages
859
The alarm sensor, which is just an automatic switch that grounds the horn located up at the box or dash when your motor reaches 145 to 150 degrees, is located with the right arrow. Pull apart the black rubber cover on the wire or stick something long and skinny that's metal in it and ground it to anything on the motor with the key on.

If it doesn't chime out then you must "hot wire" the small horn (buzzer) that's in the control box or under the dash to test that it's working.

Assuming you have a white control box with a rather large red plug back at the motor?
the alarm should sound around 196-210f with the solid tan temp wire. the later blue striped ones are closed around 240f. if it closed at 140-150f, you'd be driving around with a constant alarm!
 

evinrude2323

Seaman
Joined
Nov 11, 2024
Messages
52
the alarm should sound around 196-210f with the solid tan temp wire. the later blue striped ones are closed around 240f. if it closed at 140-150f, you'd be driving around with a constant alarm!
lol that would not be ideal!!! You guys are awesome I appreciate all the help from everyone. Making my life easier.
 

evinrude2323

Seaman
Joined
Nov 11, 2024
Messages
52
I also scored a 1993 Honda 7.5 kicker when I picked the boat up. It was said to run but for some reason it won’t get any fuel into the carb. I have taken off fuel line and I’m trying to track where flow gets stopped. Took the fuel pump off and the diaphragm was a little worn out. But even when I am pumping it with a brand new bulb I can’t get fuel to enter the carb. I’m going to pick up new fuel line and a new inline filter today. Already cleaned this carb but I’ll pull it again just to make sure. Starts when I give it a squirt of starter fluid then dies. I pulled lines off fuel pump and turned it over and I had gas moving out of it so I don’t think it’s the pumps fault. Probably a leak or something in these old lines.
 

tphoyt

Lieutenant
Joined
Jun 10, 2010
Messages
1,259
Sounds like you may have a good motor. Run it good and hard before you pull the head and check compression again. Rings may be a bit sticky form sitting around.
 

saltchuckmatt

Commander
Joined
Jul 19, 2019
Messages
2,642
Your temp wire and horn are working.....but you don't know if your temp sender is.

It's probably fine but buy a cheap IR gun at harbor freight and shoot the top of the head after warm up. Poor man's method is to put your hand on top of the head....should be hot but not scalding.

IR gun shouldn't read much more than 150 or so. Not sure what the other guy says but he's not talking head temp.

After you take it out and clear it out, remove the plugs and clean them and run some carbon guard through it.

Buy top of the line oil and mix carefully.

There is another forum for your Honda.
 

ct1762@gmail.com

Master Chief Petty Officer
Joined
Jan 17, 2019
Messages
859
Your temp wire and horn are working.....but you don't know if your temp sender is.

It's probably fine but buy a cheap IR gun at harbor freight and shoot the top of the head after warm up. Poor man's method is to put your hand on top of the head....should be hot but not scalding.

IR gun shouldn't read much more than 150 or so. Not sure what the other guy says but he's not talking head temp.

After you take it out and clear it out, remove the plugs and clean them and run some carbon guard through it.

Buy top of the line oil and mix carefully.

There is another forum for your Honda.
not sure if i am the other guy, but i was saying the temp sender wont close until 190-210f on this motor. head temp should be 125-152.5f at the top of the head at 900rpm yes.
 

evinrude2323

Seaman
Joined
Nov 11, 2024
Messages
52
Hi everyone,

I purchased a trim unit as I don’t have one in my boat. It came off a 115/120hp evinrude. I thought it would fit and it looks like it will but it’s just barely too large to slide ito place. Is this going to work out for me? I am trying to think if it could work. No worries if it won’t but it’s so close and the hydraulics all want to line up.
 

ct1762@gmail.com

Master Chief Petty Officer
Joined
Jan 17, 2019
Messages
859
Hi everyone,

I purchased a trim unit as I don’t have one in my boat. It came off a 115/120hp evinrude. I thought it would fit and it looks like it will but it’s just barely too large to slide ito place. Is this going to work out for me? I am trying to think if it could work. No worries if it won’t but it’s so close and the hydraulics all want to line up.
there are 2 main units: early model and 1991-up fastrak. 115hp and 120hp were made for many years and completely different motors, but 1991-up took fastrak and 1978-1990 had the older style. does your trim unit have 1 big pin at the bottom, or 3 bolts each side? yours is the 3 bolt one
 

evinrude2323

Seaman
Joined
Nov 11, 2024
Messages
52
there are 2 main units: early model and 1991-up fastrak. 115hp and 120hp were made for many years and completely different motors, but 1991-up took fastrak and 1978-1990 had the older style. does your trim unit have 1 big pin at the bottom, or 3 bolts each side? yours is the 3 bolt one
Here’s some photos: it’s the width of it that I’m having trouble fitting into the cavity by the transom. Not sure if I have to remove some parts first to get it in or what.
 

Attachments

  • IMG_6004.jpeg
    IMG_6004.jpeg
    1.8 MB · Views: 3
  • IMG_6005.jpeg
    IMG_6005.jpeg
    1.8 MB · Views: 3
  • IMG_6006.jpeg
    IMG_6006.jpeg
    2.1 MB · Views: 3
  • IMG_6008.jpeg
    IMG_6008.jpeg
    2 MB · Views: 3

evinrude2323

Seaman
Joined
Nov 11, 2024
Messages
52
Guy said late 70s early 80’s. It’s a tight squeeze but I damn near can fit it. I wonder if I have to move engine out of the way to install it to transom rack then drop motor back on top.
 

tphoyt

Lieutenant
Joined
Jun 10, 2010
Messages
1,259
If it is in fact the correct unit you will also have the transom bracket bolts that go through the transom to deal with. If your lucky they we have a bit of wiggle room but if not you will have to deal with that as well. With the tilt tube nuts lose and the transom bracket bolts removed you may gain enough space to get it in there. If it’s the correct unit.
 
Top