'79 evinrude 70hsp bogs until warmed up

[FastOrange]

When I try to give it full RPM it bogs or dies. unless it idles for 5 to 10 minutes and me feathering the throttle she'll eventually run at full RPM with no issues until I shut it off again and let it cool down. The warm up period seems to be getting longer and longer. It never did this before. Plugs look good. Please help

 

[hoeser]

Re: '79 evinrude 70hsp bogs until warmed up

Sounds like fuel delivery to me. Pump the bulb while you are opening the throttle and see if it picks up. If your warmup period is longer, check your thermostat. It's probably stuck open.

 

[jtexas]

Re: '79 evinrude 70hsp bogs until warmed up

In addition to the above, make sure the throttle cam is hitting the roller right on the mark, not before. How long since the last carb rebuild?

 

[FastOrange]

Re: '79 evinrude 70hsp bogs until warmed up

I've only owned it for a year and have yet to do anything to the carbs.Is the thermostat a cylander with a rod and spring coming out of it to the choke? I'm new to boats........ so the fuel tank must be venting while running the motor right? I also noticed a bit of oil/gas around the outside of the carbs. Is it Ok to clean them with carb-cleaner. How about spraying carb-cleaner into the carbs via the airbox while it's running?

 

[hoeser]

Re: '79 evinrude 70hsp bogs until warmed up

Never spray carb cleaner into the carbs with the engine running, or the carbs connected to the engine for that matter. Carb cleaner strips oil from metal surfaces. It works like a flammable brake cleaner. You can clean the carbs with carb cleaner with them removed from the engine, then dry them out after with compressed air.

Let your engine fast-idle (~1100-1200rpm) for 5 full minutes at the dock and then place your finger on the cylinder head. Your finger should become uncomfortably warm after 3 or 4 seconds. If it feels only slightly warm and you can keep your finger on it all day long, your engine isn't warming up properly likely because the thermostat is stuck open. If you burn your finger, you are overheating your engine. Not sure where it is located on your engine, but someone here should be able to tell you.

If your engine is actually overheating you have another issue. Weak impeller or thermostat stuck closed (much less frequent than stuck open, but it still happens).

Something tells me this whole thing isn't temperature related though. Fuel and oil on and around the carbs... could be a fuel leak, you don't want this and it could be your issue. Inspect hoses and fittings.

Your fuel tank must be venting or the vacuume in the tank will overpower the fuel pump leading to fuel starvation at high rpm.

 

[jtexas]

Re: '79 evinrude 70hsp bogs until warmed up

thermostat is at the top of the cylinder head in the back. The device you described is the "choke solenoid". That solenoid should actuate when you push the key while turning it to "on" or "start". When it does, all three choke plates should go from open (fully horizontal) to closed (vertical). Any other result will adversly affect the operation of your motor.

If gas comes out the carb throats while you squeeze the primer bulb then your float valves are shot. If gas is on the outside of the carbs, then the bowl gaskets (or maybe another gasket) is shot. No big deal, gaskets, valves & seats come in the carb rebuild kit you can get on iboats for about $11 apiece and well worth it.

fact that you can "feather the throttle" makes it sound like a link/sync issue.

Any case those carbs are fairly simple devices and the fact that you have a leak means they need rebuilding regardless of other symptoms.

A manual will pay for itself many times over.

 

[FastOrange]

Re: '79 evinrude 70hsp bogs until warmed up

well... I went and squeezed the primer bulb and noticed a leak on the line where fuel exits the fuel pump. There was no clamp on that end but the other lines attached to the pump had clamps on them. You can see that there is an imprint of a clamp that used to be that particular line. Could that be the problem?

 

[jtexas]

Re: '79 evinrude 70hsp bogs until warmed up

It needs fixing, but it's not causing the symptoms you described in your original post, nor is it causing the carbs to leak fuel.

btw, zipties are usually used to clamp the fuel lines on the pump & carbs.

 

[FastOrange]

Re: '79 evinrude 70hsp bogs until warmed up

the only marine shop in my town quoted me @ 400 -500$ to rebuild the three carbs

 

[jtexas]

Re: '79 evinrude 70hsp bogs until warmed up

3 carb kits @ $11 = $33
2 cans berryman's b12 @ $3 = $6
1 can aerosol b12 $4
1 OEM factory shop manual $50

total $93

satisfaction of doing it yourself: priceless

 

[FastOrange]

Re: '79 evinrude 70hsp bogs until warmed up

I took her for a spin yesterday and she had no problem hitting top speed right away. After trolling for an hour or so she was a little boggy for about 2 seconds when I juiced her up again but nothing like how it was before. I am still gonna rebuild and clean the carbs though just not right away. However I'm still a bit puzzled. This lake I was at yesterday was about 2000' lower in elevation too. Jetting? I'm used to this kind of thing from snomobiling and I guess 2 strokes react to the same things