70 HP Evinrude Problems Need Help :)

[Marauderk]

Hello <br /><br />I have a 70 HP Evinrude Model #70873C that runs well at idle and deciced to take it out to the lake to see how she ran. Used new fuel tank and line to take with freash correctly mixed gas. <br /><br />When i got out in the open after the motor was warm i opened the throttle and the boat took off great but after about 5 min she slowly lost RPM till she was bogging and moving bearly above idle speed with the throttle wide open. Figured the carbs where dirty and took them off and cleaned them and replaced all fuel lines, put new plugs in.<br /><br />Cranked her up she idled smoother than she ever has and hook her back out to the lake the next day, let her warm up and took off and she go full throttle for about a min but then it would <br />start to rev up then down and sound like she was bogging down. <br /><br />thinking it might be in the fuel pump so buying a new kit or new pump if i can find one. <br /><br />Any ideas or suggestions to one that is close to losing his mind lol. the trip to the lake takes almost 2 hours so i can't test in water with out making that trip <br /><br />Thank you <br /><br />Brian <br /><br />P.S. i am sure i left out needed info or posting is confusing i am dsylisic and wife was not here to proof read Sorry about that

 

[DHPMARINE]

Re: 70 HP Evinrude Problems Need Help

Brian,I wish I could move the lake closer,but I'm limited on things like this (grin) .It does sound like the fuel pump.If you go to the lake again,and the problem occurs,squeeze the primer bulb on the fuel hose.If this rectifies the problem it is probably time to replace the fuel pump.<br /><br />DHP

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

Thank abd trust me wish you could move the lake closer or me closer to the lake I have tried pumping the bulb and it did not help also noticed that the bulb does not stay hard and i just noticed today behind the pump on the motor when i squeeze the bulb a small amout of fuel comes out of the back of the pump.

 

[Joe Reeves]

Re: 70 HP Evinrude Problems Need Help

You state "when i squeeze the bulb a small amout of fuel comes out of the back of the pump."<br /><br />That indicates the diphram is cracked. Rebuild or replace the fuel pump.

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

I put a new fuel pump on and it runs better but still does the same thing. I am getting spark and running on all cylinder plugs are new and gapped correctly. went over fuel lines again all new and tight.

 

[cvx35]

Re: 70 HP Evinrude Problems Need Help

Is your new fuel tank from Walmart? The pickup tube in the tank might be too small.

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

Bought the tank and pickup from a local boat store. but i will check out the size when i get home to see if it is as big as the old one... <br /><br />Funny thig went to cut the grass today and my mower is a little 5 hp pushmower and it sounds just like the boat motor rev and dies revs and dies lol <br /><br />Thanks <br />Brian

 

[cvx35]

Re: 70 HP Evinrude Problems Need Help

Heh Heh, Try IMOWERS.com

 

[fireman57]

Re: 70 HP Evinrude Problems Need Help

Did you try squeezing the primer after your pump rebuild? Next time it bogs do a spark check while it is running with a timing light and a friend. Or insulated pliers and a really good friend.

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

he he little late for the insulated pliers i warned my brother but he did not listen lol...<br /><br />So i know for sure # 1 has a great spark lol<br /><br />Runs great on earmuffs or in a tub of water just when it gets a load on it in the water. After the new pump the bulb stays hard will not get to the lake again till this weekend so i will make sure of the timing and take the carbs off again and clean them again just to make sure thats not the problem. Also thinking of running so seafoam thru it but not sure if thats a good thing to do on a motor that i know has never had it done.<br /><br />Thnak for all the info

 

[fireman57]

Re: 70 HP Evinrude Problems Need Help

I'd get it running good first and then use Seafoam every tank. I think you and I must have the same brother.

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

Well we could have the same brother if that is the norm for him cause thats my little brother you tell him something and he will do it just to show you he knows more lol. But after nearly biting his tongue off he decided to use my my rubber coated pliers but of course he had wet hands and just washed them off and i warned him once again that it would shock him and he did it again lol.... almost worth having the motor running crappy to see it

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

Ok new fuel pump on and took her back out and she is still bogging down when more than about half throttle. Thinking it could be in the carbs maybe something clooged them up again ? good spark, good plugs what is the best gap for the plugs right now there at .40.

 

[OBJ]

Re: 70 HP Evinrude Problems Need Help

Gap is ok. Couple things to try.<br /><br />Take a spray bottle of premix with you. With the carb cover off, run the engine till it bogs. Spray some premix into the carbs and see if it picks up. If it does, problem still in fuel system. If it don't....<br /><br />Take a timing light and connect it to each spark plug wire and see if you got spark to all three cylinders. Problem may lie in an ignition component reacting from the heat of the engine.

 

[sprouticus]

Re: 70 HP Evinrude Problems Need Help

i just read over this thread because i am having a similar problem with my 77, 70 hp evinrude I just bought. This is my first "big boat"(had a 12' aluminum before) so I know very little. I have 3 tanks for my motor, and it seems to me that the problem only occurs with the one tank, could be just a coincidince though. I have to ask though, how do you spray premix into the carbs while you are at WOT, and not go flying off the back of your boat, especially if shooting the premix actually improves the RPM, and speed. I think it is still to cold up here to try that. Anyway, like I said, I am a rookie.

 

[OBJ]

Re: 70 HP Evinrude Problems Need Help

You take a helper with you in the boat. One to drive, the other to do the fiddling around with the engine.

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

Ok Went out today and motor ran ok for about a min then started bogging down till it would hardly run. Tried spraying premixed in carb and it did not help checked to make sure all plugs are firing and they are. hecked to make sure i still had my mind nope i have lost it

 

[fireman57]

Re: 70 HP Evinrude Problems Need Help

They may be firing weak under a load but enough to show up on a timing light. I know that you don't want to do this but have someone pull the plug wires one at a time when it bogs. If the rpms do not change then that is your suspect cylinder. It still sounds like you have dropped a cylinder. When it bogs badly you can also pull the plugs and see how they look. If you have one that is black and wet I would suspect that cylinder.

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

Well this sounds like the perfect job for my brother to do lol. if i can just talk him into doing it i will give it a shot and see but i do seem to have one plug thats wet and dark looking

 

[Marauderk]

Re: 70 HP Evinrude Problems Need Help

Ok i have the top plug that is dark and wet looking after running at full throttle and bogging. the middle plug looks good and clean and the buttom plug is a small bit wet but not bad