1975 70 HP running issues

[joelyons50023]

Hello all I have checked comp. 145-150 all across, replace surface gap plugs with proper plugs installed thermostate where there wasent one, cleaned the carbs twice and made sure the 3 little holes are open(30 jet in the top 35 for the intermediate ? for main could not remove but clean) I set the foat height to paralelle with the gasket surface and float needle is doing fine, replaced fuel hose from tank to pump. I have adjusted the throttle as per the manual so that the ign plate moves before the throttle plates do and that the lower mark on the throttle cam lines up center with the roller when they do touch. My problems are this 1.Is it supposed to idle without the throttle cam touching the roller when warmed up b/c it wont? 2. Can not give full throttle without it sounding boggy and possibly droping a cylinder. I took the boat out today and with just me in it it did better like prob. 15-20mph (sorry no speedo yet) but when I went back and got my wife and kid and dog it went right back to boggy past half throttle. I squeezed the primer bulb while at full throttle and no change bulb was med. firm id say but not rock hard. Here are the things I wana check 1. spark on all three with a gap jumper and not just the spark plug to block 2. I want to just run a straight line from the primer bulb to the pump to nix the connectors 3. Check full advance as per I read on here to do and possibly while on the lake.(I know its not over advanced b/c on the water I retarded the arm and ran worse the further I went.) Any other ideas or something I am missing. Also I am running 50-1 ratio fuel and rebuilt the water pump. Any help would be great.

 

[Monte1961]

Re: 1975 70 HP running issues

What do the spark plugs look like now? We can tell a lot from them. If at all possible, post some pics of plug and your model # of engine. Good luck. BTW, Welcome to iboats!

 

[joelyons50023]

Re: 1975 70 HP running issues



1 2 3 from left to right. Sorry about the quality its from my phone bc the wifes camera is nowhere to be found.

 

[soundchaser]

Re: 1975 70 HP running issues

Ethanol is eating hoses up pretty regularly now. Fuel injection hose may work better.

 

[joelyons50023]

Re: 1975 70 HP running issues

I havent ran e-10 in the thing since ive had it. One of the biggest things for me is it supposed to idle warm w/o the throttle cam touching the roller if so then i have a problem all the time not just at wot and to tell ya the truth I haven heard this thing run good since ive had it so it sould just be hitting on 2 most of the time and I don't know the difference. I need to test spark, coils and pickup. The coils look kinda old anyways. If i remember right 1 and 3 coils are black and 2 is green so who knows. And would it be wise to go up a size on the idle jet like I seen on here for a better mix?

 

[joelyons50023]

Re: 1975 70 HP running issues

bump

 

[Daviet]

Re: 1975 70 HP running issues

I guess the two things I always check first is spark and compression. Sounds like your compression is ok, your spark should jump a 7/16" air gap. Make sure your coils don't have any cracks in them.

 

[joelyons50023]

Re: 1975 70 HP running issues

Checked spark on all three and all were bright blue and just fine.
hooked up timing light and checked full advance timing and it was at 12* but from what i read that for some reason it will gain 4 degrees on its own so it is at 16* on the water wot when it is supposed to be 17. Off but not far? Still don't know for sure if it is supposed to idle when the throttle cam is not touching the carb. roller though.

 

[joelyons50023]

Re: 1975 70 HP running issues

In the manual it says that when the throttle cam touches the carb roller the timing should be at tdc +/- 1 but can i check that the same as the wot timing as per the automatic 4* advance?