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carb issues 25r69d

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druthomas

Member
Motor ran great but didn't idle for longer than 20 seconds. I did a carb kit to fix it. Now motor idles but runs terribly across the board. I think jacked the timing up, any help on how to reset it or any othe ideas would be great.
 
Ok I have done some troubleshooting so hopefully someone can help me figure this out. The motor starts and idles normally. After warm up if you punch it she revs right up. it then bogs down and will only run sooth at 1/3 throttle. If you got to idle for second you can punch it again. It's like it sucks all of the fuel out of the bowl and can't keep up. Fuel pump maybe???
 
druthomas said:
Ok I have done some troubleshooting so hopefully someone can help me figure this out. The motor starts and idles normally. After warm up if you punch it she revs right up. it then bogs down and will only run sooth at 1/3 throttle. If you got to idle for second you can punch it again. It's like it sucks all of the fuel out of the bowl and can't keep up. Fuel pump maybe???
Click to expand...

Try it again but this time manually pump the primer bulb while running. This will basically temporarily take the place of the fuel pump. If you can run like a scalded dog, you probably have a fuel pump issue.

Also, do you have a fuel tank that has vent setting? If so, make sure it's vented.


CMOS
 
CMOS said:
Try it again but this time manually pump the primer bulb while running. This will basically temporarily take the place of the fuel pump. If you can run like a scalded dog, you probably have a fuel pump issue.

Also, do you have a fuel tank that has vent setting? If so, make sure it's vented.


CMOS
Click to expand...

I actually tried that on the last outing. The fuel bulb gets hard but there is no change at the engine. I wonder if a check valve in the fuel supply system has failed and gives just enough gas to run at 1/3 throttle?
Also I have the tank vent full wide open.
 
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Possibly.

Did you replace the fuel lines before doing the carb kit? If not, you could have small pieces of crud that got into the carb's high-speed jet.

Let's see what some other members have to add.

CMOS
 
I did not replace the lines before. I noticed a bit of air from the pump to the carb running it in the trash can today so I checked and replaced all of the lines. I also found that the vertical oil line was broken at the nipple. I dont know if this affects the top end but it makes sense that I would have broken it when I did the carb kit. I ran again and it seemed to have almost no bubbles coming from the pump. I need to get in the lake for a test.
 
I have put the original float and needle back in from when it was running fast and there was no change. I set float up to be level when the needle is closed.
 
OK will do, I have an update though. i went to WOT and it initially surged to full power like usual then bogged down. While it was bogging at WOT I popped the cover and physically rotated the choke toward closed. It went right to full power and and ran normal. I am thinking the choke helped it draw more fuel. So think something is restricting fuel on the tank side?
 
You cant surface the carb, only the bowl. If it picks up rpm with choke pulled it lean from : incorrect level or delivery issue ....what type of tank and line you using?
 
So I swapped to a tank, line, and bulb that I know work perfectly. If this doesnt do it I will check the flange for an air leak. I did make sure the sync was set as well.
 
Well the new tank and line did not change anything. Same exact rev up and bog down. I did run around for a while with my finger on the choke and it ran full power as good as it ever has. It would make sense there is an air leak at the flange or the bowl that causing it to not suck enough gas at WOT. I would thinks it's the flange and not the bowl because I can pump the bowl full and don't see any gas leaking.? This would explain the sudden change after I initially worked on it.

Question? Am I safe to use some black permeated gasket goop on both gaskets to help seal them up.
 
druthomas said:
Well the new tank and line did not change anything. Same exact rev up and bog down. I did run around for a while with my finger on the choke and it ran full power as good as it ever has. It would make sense there is an air leak at the flange or the bowl that causing it to not suck enough gas at WOT. I would thinks it's the flange and not the bowl because I can pump the bowl full and don't see any gas leaking.? This would explain the sudden change after I initially worked on it.

Question? Am I safe to use some black permeated gasket goop on both gaskets to help seal them up.
Click to expand...

Should not need to use goop on those gaskets....

CMOS
 
Just wondering if it would hurt anything? Would red rtv be better? I will try to resurface the ears if bent but would like some insurance.
 
each of these connections/parts are taken apart, when running good, every year or two, when running crappy, every day/week or two, to have to clean/scrape that stuff off is a pain, especially on the manifold and keeping stuff out of there.
kincrwbr1 is way more experienced then myself, i'd go with that
 
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Did you use a OEM kit as the some of the aftermarket kits the gasket is to thin on the emulsion tube and will cause this..
 
If the emulsion tube is the tube that comes up through the bowl this could be an issue. The bowl gasket I replaced went around the tube. The new one did not. This was a Sierra kit.
 
Ok a huge lightbulb just came on. The bowl gasket was different and I just didn't put on the little donut gasket around the emulsion tube. Luckily I kept everything and still had it. Stupid mistake I hope this solves the problem.
 
Well that solves the great mystery of why there was no power. Motor runs like a champ and my heavy old 14' starcraft was hitting 22mph with 2 people and fishing gear. Thanks for the help guys I appreciate.
 
Well, the old boy hits 25mph with just me in it. Its running great. How much gas should something like this burn per hour? Its definitely thirsty running on the high end.
 
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