1978 70 Hp Evinrude reoccuring issue

[randyray41]

Had my boat in shop 3 times in last month. 70 hp Evinrude model # 70873C. My issue is it will idle, but it has no pulling power. It won't get over 2k rpm while in gear but in neutral it will rev up fine.
So far, my boat mechanic has replaced all fuel lines,as well as bulb, and I put in a new 9 gallon fuel tank. Fuel pump rebuilt as well as cleaned all 3 carbs. Spark check is fine. yet same thing happens over and over. Boat has 125, 124, 125 compression. The first time it was a piece of trash in bottom jet, after it was cleaned boat run great for two days then same issue, back to shop it went. thats when he cleaned the other 2 carbs. Picked boat up and last Sunday back to water. It ran for about 300 yards, I idled down to go back to dock and same crap again, would not go. Will run about 2k rpm. Loaded it up and back to shop it went.
It will crank right up, but it will not go. Now he is saying it may be stator? Something about low speed and high speed part of stator since i'm not a mechanic, I don't know.
Anyone have any thoughts on what may be the issue?

 

[jakedaawg]

I dont recall a two speed tlstaor on those. That was a merc thing. But thats before my time and i could be wrong.

Do a spark check with timer base fully advanced.

Clean carbs again and verify that all fuel lines were replaced. Including from the cowl to the pump and pump to carbs. Your getting stuff from somewhere.

Do a fuel sample into clear jar. New fuel does not = good fuel.

 

[fireman57]

sounds like you keep picking up junk from your tank. Do you have a fuel filter?

 

[oldboat1]

^^sounds like you are feeding some contamination from the tank.

 

[randyray41]

all lines from carb to tank have been replaced. Boat is at shop. I was curious about stator.. Seems to me like if stator was issue it would malfunction in neutral as well. Fuel is non-ethanol and inline filter is brand new. fuel was tested last time in shop and was good. Now this is new fuel along with new tank. I believe its fuel issue, just trying to keep mechanic honest!

 

[fireman57]

try running it with a known good 6 gallon portable tank and see what happens AFTER you clean the carbs again.

 

[fireman57]

also have someone pump the primer bulb when this happens to override the fuel pump. tiny pieces on rebuilding these things

 

[randyray41]

Tank is brand new right out of box. I replaced the old tank thinking same thing. Pumping bulb has no effect on motor.

 

[fireman57]

Still sounds like carb issue. It runs good and dies after they clean them.

 

[randyray41]

Motor won't die. It will idle, it just won't push boat.Will run just enough to create a wake. Boat won't come out of hole. Will only do 2000 rpm in gear. In neutral it will rev past 2k rpm, always heard not to rev to much in neutral.

 

[F_R]

Has anybody investigated the possibility of it getting water into a cylinder (s)?

 

[fireman57]

Just out of curiosity did you try bumping the primer solenoid when it wouldn't go any faster?

 

[randyray41]

I don't think so but compression is great on all 3 cylinders. Wouldn't I have a reduction in compression if water was getting into cylinders?

 

[fireman57]

water doesn't burn. Compression will stay the same until you get too much water in there and no lubrication.

 

[randyray41]

I don't know what a primer solenoid is. If its the choke, no I didn't. My mechanic asked me that question

 

[fireman57]

If it picks up and runs when you hit the "choke" then you have junk in you high speed or mid range jet. If I remember you just have high and low on those carbs but it's been a while.

 

[randyray41]

Where would water be coming from should that be issue? head gasket?

 

[fireman57]

Head gasket or the side water jackets. Have changed two of the water jacket sides. Pain in the butt but fixed it. First determine if you are in fact getting water in the cylinder(s).

 

[interalian]

Revving in neutral is no load, so I would expect it to rev higher. When you're trying to come on plane, the motor is working a lot harder and needs a lot more fuel. BTW, revving too high with no load can grenade your motor.

 

[racerone]

Answer this question.--Does spark jump a gap of 7/16" or more on each lead, yes or no ?