1990 70 Evinrude stalls after 1 hour full throttle

[catman977]

I have a strange problem with my 1990 70 hp Evinrude model E70TLESB, I've rebuilt all 3 carbs,
I've replaced all 3 Coils and Power Pack. When I put it on the river, it Idles good and gets up on plane good, and runs up river at full throttle, for about a hour, then it starts to miss, or blubber like its dropping a cylinder. I barely make it back up on the trailer. I have it on a 20' Pontoon, which makes it hard to trouble shoot on the water. Can these new Coils, or even the Power Pac malfunction after their warm? Can the Timer Base assembly, under the flywheel cause this problem? I know a lot about motors , but there's a lot of variables on a 2 cycle. Can anyone steer me on what to replace next? Thanks to all

 

[racerone]

Why are you replacing parts hoping to be the blind squirrel who will find a nut ??----Test run with another fuel tank and hose, borrow a set-up.-----Does the tell tale hose come of the side of the block or the top ?----Have you replaced the water pump along with the latest repair kit ?

 

[catman977]

Why are you replacing parts hoping to be the blind squirrel who will find a nut ??----Test run with another fuel tank and hose, borrow a set-up.-----Does the tell tale hose come of the side of the block or the top ?----Have you replaced the water pump along with the latest repair kit ?

Yes I did drop the lower unit, and replaced the water Pump also the plastic screen for the pump intake. The tank is an 18 gallon moller and transparent, I have a transparent in line fuel filter, between the squeeze Bulb and engine . I had a friend this time out, that held the wheel, while I troubleshot everything, the filter was at 3/4 fuel and pumping the bulb didn't help. It has to be a Thermal problem, or it wouldn't run so good the first hour would it ? This 70 came new with this Sun Dancer Pontoon, and I've tried to refurbish everything, with new parts on the motor. I want to take friends and family out and feel safe with them on the river. The Fuel Line and the filter have been changed, and I've had the Tank off and flushed, and new fuel each time out. But with todays Fuel it only last a coup[le of week, unless you use supplements. The hose for the Tank comes off the top, via a tube down to the bottom of the tank. I'd love for it to be that simple.
Thanks for the input.

 

[catman977]

Hi racerone I've been giving thought what you said about the fuel tank, I hope your right. I'll check the tank Vent today, we have those black wasps here in Missouri that love to pack clay or mud into any small hole, I guess to lay eggs.?? It would make since, that no vent the tank would create a vacuum if the cap is tight. I may adopt the new avatar you gave me " Blind squirrel" Lol

 

[racerone]

Does the tell tale ( pisser hose ) come of the side of the engine block or off the top of the engine block ?

 

[catman977]

Do you mean the hose that Pees the water pump for visual? I don't recall anything else. Yes it starts out of the water manifold, on the Port side of the motor, and exits the starboard lower side. It also Tees to a Gage on the Helm. What's that got to do with my Stall problem? I'm in the process of tearing down the cover over the fuel tank, which is mounted under the live well. It's not easy to get to. I'm in this restoration too deep to give up. I will replace the hose for the vent, and make sure the chrome vent port is clear. I will probably put some kind of screen or guard, to keep the critters out during storage. I love your input. I have 5 Evinrude's and going to fix them up and get rid of them. 30-48-50-70-90. I also have two 440 Chrysler Magnum Marine engines, (one built for reverse rotation.) Both have Borg Warner velvet Drives. Also for sale.
Thanks for your help.

 

[racerone]

Well there was a service bulletin that came out in 1994 to move the tell tale to the top of the block.----To me it means that no one who cares has looked at this motor over 25 years.----Post your compression test numbers.----There were lots of issues with #2 cylinder scoring the piston.

 

[Crosbyman]

What's that got to do with my Stall problem? .....

when you don't **** things get ugly real fast .

 

[ct1762@gmail.com]

racer is asking because the indicator elbow MUST NOT be on the bottom of the exhaust housing. it must be re-located to the top of the block (new updated water pump kit has all the parts you need save anaerobic sealant and a drill bit/grease). that way it "burps" the air out so water can completely fill the block and cylinder head. the service bulletin specifically warns against pontoon boat installations, as the wake is very turbulent and creates less pressure for the pump. make sure it's not overheating!

 

[ct1762@gmail.com]

What's that got to do with my Stall problem? .....

when you don't **** things get ugly real fast .

if it's overheating, it will stall and be hard to start again. that is if no damage was done.

 

[catman977]

if it's overheating, it will stall and be hard to start again. that is if no damage was done.

Hi this is the blind Squirrel again, I pulled the Live Well off the top of the fuel tank, hoping I would find a plugged tank vent. Everything was clear. I replaced the hose with a new hose, I haven't started the motor yet, until I hear from you.
Yes the hose for the water tell all, comes off the bottom of the water manifold. Is the kit still available? If it's just a matter of moving the elbow to the top, I can probably do it tomorrow. I have pipe taps to rethread. Is there any specific place they want it, or as high as possible?
Some History of this motor, when I bought the pontoon from the original owner, He said it originally was a VRO, which malfunctioned, and he had the power head rebuilt. I know this is true, because I had a bad head gasket, and water was getting in one of the cylinders. I pulled the head off and noticed all the Pistons were .020 over. I've ran it on Table Rock for a few hours, off and on. This overheating problem, is new to me, I will gladly change output port for the Tell Tale Tomorrow. Probably the last good day before cold sets in. I will do a Compression Test also and post my findings. the last one I did, all Cylinders were 120 each. Thanks for all your input (Blind Squirrel out lol)

 

[ct1762@gmail.com]

Hi this is the blind Squirrel again, I pulled the Live Well off the top of the fuel tank, hoping I would find a plugged tank vent. Everything was clear. I replaced the hose with a new hose, I haven't started the motor yet, until I hear from you.
Yes the hose for the water tell all, comes off the bottom of the water manifold. Is the kit still available? If it's just a matter of moving the elbow to the top, I can probably do it tomorrow. I have pipe taps to rethread. Is there any specific place they want it, or as high as possible?
Some History of this motor, when I bought the pontoon from the original owner, He said it originally was a VRO, which malfunctioned, and he had the power head rebuilt. I know this is true, because I had a bad head gasket, and water was getting in one of the cylinders. I pulled the head off and noticed all the Pistons were .020 over. I've ran it on Table Rock for a few hours, off and on. This overheating problem, is new to me, I will gladly change output port for the Tell Tale Tomorrow. Probably the last good day before cold sets in. I will do a Compression Test also and post my findings. the last one I did, all Cylinders were 120 each. Thanks for all your input (Blind Squirrel out lol)

 

[catman977]

Ok guys today I relocated the Tell Tale water output from the lower Port side of the engine, to the top of the Block, as the 1994 Bulletin, I did a Compression Test to see if any Piston or Cylinder walls had been damaged. All Cylinders tested 120+ each Cylinder even. I haven't ran a Test on the flush hose yet, tomorrow. I read some other forum, that the Thermostat spring must be changed, with a stronger one. Is that true, and is it a special part number?
Thanks to all, I'm hoping this solves the Stall problem. racerone hope this is the Nut I was searching for Lol, This motor was probably passed over for this OMC change, because the prior owner had it on a 3 acre lake, and it had an easy life until I got it, and made it work pushing against a 7mph current, up the Missouri River. I doubt if he ever took it any place for service. When I got it I used it on short trips to a 40' deep fishing hole on the river about 2 miles from the ramp. Lately that ramp was unusable, because of all the high water and flooding. So I had to go 16 miles downstream, to a State well taken care of ramp, then full throttle to the big fishing hole, back up river. This is the most running it's had since I've owned it, except a similar run on Table Rock in Branson Mo. This time I had a head gasket leaking, which I replaced when I came home. Keep the good Info coming! Thanks again.

 

[racerone]

I do not believe a motor has to work any " harder " in a current of 7 mph than on a calm lake.

 

[ct1762@gmail.com]

the upgraded t stat spring is in the new kit, along with the indicator elbow. i've had a few i changed the spring to a stiffer one, and others I didn't. don't see the difference as long as it unseats at high speed to bypass the tstat and doesnt over-cool at idle i see no issues.

 

[catman977]

racerone it's the hour running at full throttle that I meant, and I get less speed according to my sonar GPS, going up river than down, so something is working harder to get there. I'll try running with out the stiffer spring in the thermostat and watch the temperature close for a bit. Thanks

 

[racerone]

Your speed over the bottom changes.----That is due to the water moving.----Motor still works the same !

 

[catman977]

Try Rowing a boat up the Missouri River Then Turn around, which one requires less work?

 

[catman977]

I did get my Motor tested for the new Tell Tale Pee move worked great. My motor ran like Crap tho. I Swapped the Power Pac and the original, fired all three Cylinders. Here's a picture of the new Bad Power Pac. and the Refurbished 70 Made In the USA. It don't like Chinese made parts.!!

 

[catman977]

racerone is there a good source for another Power pac, that I can buy and be good?