1975 evinrude 70hp runs great but doesn't go...

[Forsaken]

hi, this is my first post here so don't be too mean...lol. anyways, i just bought a 1976 winner with a 1975 70 horse evinrude that runs great, well... kinda. first time i took it out it ran great for about 3 hours then on the way back to the ramp, it just lost everything... i thought i got some moisture in the coil or something but, its firing fine on all cylinders with no shaking, missing anything... so i did the old silicone trick on the coils to keep moisture out. then yesterday, i took it to the lake and it did it from the start. if your sitting in the water dead still and put it in gear then go straight to WOT it takes off like a bat outta hell then just...blah. it just looses all power but, i can tap the auto choke on the remote a couple times and it will start speeding up. everytime i tap the switch, it revs up a little more just for a second. if i keep tapping it, i can get it almost up to full speed. my thoughts are that maybe the fuel filter is clogged or the carbs have something wrong with them... if you can help, please do it, it is much appreciated!...

 

[TD_Maker]

Re: 1975 evinrude 70hp runs great but doesn't go...

When the engine dies, check for a collasped primer bulb. Just for the hell of it, replace the entire fuel line assembly including primer bulb. It is cheap, and it could solve your problem. Also, make sure your fuel tank is well vented.

If that does not work, work your way up to the fuel pump. Clean the screen and recheck. Next, I would look for a leaky fuel pump diaphram. The entire fuel pump assembly can be rebuilt pretty in expensively.

 

[Quick-man]

Re: 1975 evinrude 70hp runs great but doesn't go...

I have an 83 75hp it had the same issue it was dirty carbs. You just bought the boat, how long was it sitting? Check the easy things first but by you priming and the engine comes to life signals a carb issue. I think it is time to rebuild. You need to disassemble and clean all carbs, you should soak them in carb cleaner and take out all orifices, follow the bath with a can of carb cleaner then compressed air if you have it. If your carbs are not clean you can be running lean and that will score your cylinders.

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

it was sitting since last summer, there is from what i can tell an inspection plate on the front of the carbs. i will pull it off and check it out in there tomorrow when i get a chance. thanks for the advice, i will get back to everyone here when i get finished with this ,"list", of stuff to do...lol.

 

[jtexas]

Re: 1975 evinrude 70hp runs great but doesn't go...

forsaken your '76 has traditional choke plates, different from quick-man's '83 primer system, but the indication is pretty much the same. There's your answer -->

I have an 83 75hp it had the same issue it was dirty carbs. You just bought the boat, how long was it sitting? Check the easy things first but by you priming and the engine comes to life signals a carb issue. I think it is time to rebuild. You need to disassemble and clean all carbs, you should soak them in carb cleaner and take out all orifices, follow the bath with a can of carb cleaner then compressed air if you have it. If your carbs are not clean you can be running lean and that will score your cylinders.

BTW, aerosol carb cleaner in place of compressed air has worked for me. Don't risk damaging the jets with a screwdriver if you don't have the 'special tool' - just clean 'em in place.

Also, if ya haven't already, replace the old gasoline.

 

[tashasdaddy]

Re: 1975 evinrude 70hp runs great but doesn't go...

carb tool for jets, can be made from quality screw driver.
http://i155.photobucket.com/albums/s311/frankr_photos/FixedJetScrewdriver2.jpg?t=1177353186

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

heres a picture of all three carb openings. if you cant tell, there are little screws at the top of the openings, what are they? the one on the top carb is tightened all the way in, the other two are loose and almost all the way out... do they control the fuel? if so, then how do you set them?

 

[tashasdaddy]

Re: 1975 evinrude 70hp runs great but doesn't go...

those are the slow speed needle valves, no wonder it won't idle. the top is not getting any gas, the other two are probably flooding.. here's the adjustments. do one carb at a time.

Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway

 

[burroak]

Re: 1975 evinrude 70hp runs great but doesn't go...

I'm from an old Scottish lineage and never want to throw money at a problem. Start with the fuel tank and fresh fuel mix, check for leaks in the hose. Tighten all connectors. To satisfy your curiosity borrow a known good fuel line. If the problem persists, pump the bulb and see if that keeps it running. If so, it's likely a bad fuel pump. If the bulb is firm and choking is the only thing that will keep it running, dig into the carbs. It looks as if there are three of them. By the time you finish them, you will be giving advice on iboats.

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

here are some close ups...


top cylinder...

middle cylinder...

bottom cylinder...

i need to know really badly how to set these screws. i think this may be my problem. as i said in my other post, the top screw is ALL the way in, and the other two are out and loose. something tells me there not supposed to be loose...

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

thanks... i will get right on that tomorrow...

 

[burroak]

Re: 1975 evinrude 70hp runs great but doesn't go...

those are the slow speed needle valves, no wonder it won't idle. the top is not getting any gas, the other two are probably flooding.. here's the adjustments. do one carb at a time.

Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway

Does this engine have needle valves? I thought it had fixed idle orifices.

 

[Quick-man]

Re: 1975 evinrude 70hp runs great but doesn't go...

I think it depends on the carb or maybe were it was built, my 1983 75 hp has fixed low, mid, high speed orifices, (even though the book shows a needle valve on the low speed) and you can't see the screws that go into the low speed passage the airbox covers them and you have to take off the back plate of the air box to even see the screws. Once you do you take out one screw and the orifice is set in there. You need the "special tool" to get the orifices out.

Since tashasdaddy gave you the instructions take one of those screws out. If it has a needle then you know what to do, follow the directions that tashasdaddy supplied. If it is a long screw, then you have fixed orifices. With fixed orifices those screws have to all be tightened. So the top carb might be right (only if it has fixed orifices). If it does tighten the other two and see how she runs.

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

wow... thanks man! makes a lot of sense! the manual says it has the fixed pins, or whatever..., and i just went and checked and the screws are right at if not a little longer than an inch... considering its only like 2 and a half inches from front to back of carbs... and there isn't anything that cold be adjusted under them. its just a hole... so i tightened them all down and put a little silicone in the hole to keep them from vibrating back out again, if that was the problem... will know tomorrow! wish me luck...lol.

Thanks

 

[jtexas]

Re: 1975 evinrude 70hp runs great but doesn't go...

for future reference, its generally considered bad practice to use things like silicone on & around carburetors, they're just so sensitive to any little thing getting in there. Not to mention which, I'm not sure silicone is impervious to gasoline. Put in the new gasket that will be in the carb kits you ordered (you have ordered your kits, right?) and tighten 'em down, they'll stay put.

Let us know how that carb rebuild goes.

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

sorry it took so long to get back... where can i get a carb rebuild kit for this old motor? i am pretty good with motors so im not too worried about the rebuild itself just, ive never done anything with an outboard before.

after reading the last post from jtexas, i went and scraped all the silicone off. ive already taken the carbs off the motor and found that there are no gaskets on the carbs anywhere. i would have taken a picture but, my 1 yr old broke my camera... so i need the gasket set and a carb rebuild kit, unless it all comes together?

anyways, if you guys could point me in the right direction and give me any pointers you can for this journey, lol, it would be greatly appreciated!

thanks again.

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

lil' bump...^^^

 

[jtexas]

Re: 1975 evinrude 70hp runs great but doesn't go...

get 'em on iboats, click 'marine store' then 'engine parts', drill down to your year/model. they have 2 kits, one with floats, one without - the floats only need replacing if they're saturated and not floating, a pretty rare occurance. I re-use the plastic float hinge pin cause the metal ones in the kit don't seem to fit too well (in my '79).

good luck.................................

 

[Forsaken]

Re: 1975 evinrude 70hp runs great but doesn't go...

thanks jtexas...

ill get back to you guys sometime this week and let you guys know how it went and if that was my problem!

ps, i had no idea you could get parts from iboats...lol never did any browsing here.