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ZUKIWORLD Discussion Forum => Technical Discussion - Beginner / Repair => Topic started by: marktaylor on February 04, 2011, 07:19:37 PM

Title: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: marktaylor on February 04, 2011, 07:19:37 PM
Hi,
My 88' samurai doesn't seem to want to start.  Before, it would always crank up and then idle, but then i had to start giving it throttle to get it to start, now it will not even start.  The only way I can make it start now is by dripping 5-6 drops of gas straight into the throttle body, and then it will start. 
I thought it was a fuel pump issue, but was not.  Gas is getting to the carburetor with sufficient pressure, but for some reason, when i try to crank over the engine, it will just keep going and going without starting.  It seems that once it is initially started (with the drops of gas in the throttle body) it will idle fine, but won't if I dont.

The other problem is drivability.  for some reason I cannot get over 30mph without the Sammi starting to buck on me, and then will ultimately die.  If I wait 20 seconds and try to start it, it will start fine without any bucking.  If i keep it under 30mph, the sammi will behave; idling when stopped, and accelerate fine. 
When I first purchased the Samurai, it would do 50mph on the highways without any problem, and now I'm afraid to take it out of city streets.  The problem seems to be getting worse. I've narrowed it down to something in the carburetor, i think.
Could it be a vacuum hose or a bad sensor?

Any suggestions or information would be awesome.
Thanks,
-Mark
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: lv2fsh on February 04, 2011, 07:34:38 PM
Sounds like a plugged fuel filter or carb. Change the fillter and use some seafoam on it. If it still doesn't work. you make have to take the carb apart and clean/rebuild. Try this;

http://bbs.zuwharrie.com/content/topic,21551.0.html (http://bbs.zuwharrie.com/content/topic,21551.0.html)
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: marktaylor on February 04, 2011, 08:23:09 PM
lv2fsh,

I don't think it is a plugged fuel filter because the gas must run through the fuel filter and pump before getting to the carb, and I've already confirmed that the gas is making it to the carburetor.  However, it could be a plugged carburetor.  I almost think something is blocking a part of the carb, becuause once i put gas directly into the carb, my guess is the vacuum created allows the gas to flow and the sammi to idle, but that doesn't explain the bucking problem when driving.  I'm running some carburetor cleaner through it right now, but doubt it will help.  I'm curious to know if there is some type of sensor that could cause this.
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: lv2fsh on February 04, 2011, 09:09:12 PM
Go to Acksfac and download a FSM. There is a small screen filter ahead of the needle valve to the float. It is inside the carb. If your fuel system is compromised (dirty) it can plug that screen or anyone of the other small openings in the carb. There are other troubleshooting guides in there too. There is a glass window on the float bowl too. It is extremely hard to get everything cleaned out from the outside of the carb, you sometimes just have to go in.
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: marktaylor on February 04, 2011, 09:30:31 PM
lv2fsh,

Thanks for all your help; now I have a direction to head.  So from waht I'm saying, does it sound like a carburetor issue, and not a sensor?
How hard is it, or how common is it, for the carb jets to foul up?

My guess is the bucking is occurring because there is not enough fuel to the engine, which would support your theory of a dirty screen.  I know it isn't running rich because i would smell it, and i don't.

I'll let you know when I find something out,

-Mark
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: oak_raid on February 07, 2011, 08:40:23 AM
Go to Acksfac and download a FSM. There is a small screen filter ahead of the needle valve to the float. It is inside the carb. If your fuel system is compromised (dirty) it can plug that screen or anyone of the other small openings in the carb. There are other troubleshooting guides in there too. There is a glass window on the float bowl too. It is extremely hard to get everything cleaned out from the outside of the carb, you sometimes just have to go in.

I had this problem too (plugged needle valve screen) and my sammy was doing exactly what is being described here (bucking and stalling).  After rebuilding the carb, I replaced the fuel filter and also added a second filter between the fuel pump and carb.  I also dropped my fuel tank and made sure it was clean inside.

Find where your fuel line attaches to the carb and remove that nipple.  You can then look inside where the nipple came out and see the needle valve screen.  If it is plugged, be careful not to damage the screen when you clean out the debris.  The screen sits back inide the passage, and I had a hack of a time getting the passage cleared out.  In fact, I not only damaged the screen, I accidentally popped it out and lost it. 
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: Jluck on February 07, 2011, 10:16:41 AM
lv2fsh,

I don't think it is a plugged fuel filter because the gas must run through the fuel filter and pump before getting to the carb, and I've already confirmed that the gas is making it to the carburetor.  However, it could be a plugged carburetor.  I almost think something is blocking a part of the carb, becuause once i put gas directly into the carb, my guess is the vacuum created allows the gas to flow and the sammi to idle, but that doesn't explain the bucking problem when driving.  I'm running some carburetor cleaner through it right now, but doubt it will help.  I'm curious to know if there is some type of sensor that could cause this.


but is there enough gas making it? sometimes its enough for low rpm's but not enough for the higher demand. as easy as a fuel filter is to change I would rule that out first.
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: marktaylor on February 08, 2011, 05:14:06 PM
Oak_Raid,

Can you get to the valve screen with the carburetor still attached?  I was thinking about just rebuilding the entire carburetor because rebuild kits are  only $25 or so, but it would take a lot of time.  If you think it was just the valve screen that made yours run badly, then I might just try to clean that.
Did your rebuild kit come with a new valve screen?  And if the valve screen is dirty, will it be evident just from looking where the nipple came out?

Jluck,
I think there is enough gas making it, but am not sure.  When i cranked the Sammi over without it starting, I got a pretty healthy jet strem of gas that shot 6-7 feet.  But I agree, I will swithc fuel filters.

Just a thought, would a simple carb cleaner fuel additive do the trick, or if the problem is the valve screen, do I have to rebuild?

Thanks for all yalls help.

-Mark
Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: oak_raid on February 08, 2011, 10:08:29 PM
It is back in there, but yes you can get to it with tweezers.  It wasnt easy, but I managed to get it all out (including the screen itself....I wasnt even aware there was a screen there, i just started pulling out whatever the tweezers grabbed onto).  I didnt remove the carb to do this. 

The problem with mine was it did not have a fuel filter on it when I bought it, and someone tried siphoning my gas with a black polythylene hose.  While they were pulling the hose out, the little metal flapper in the nozzle of the fuel tank was slicing off chunks of the hose into the tank.  With no filter attached, it all got caught in the needle valve screen (it was packed solid, even inside the nipple).  I was in the woods at the time, and after i got it all cleaned out and got it running (with no screen) some of the black hose that was still in the fuel tank got sucked into the carb itself.  I didnt bother trying to rebuild it myself but bought a rebuilt one off the internet.  Found one on sale for $149. 

Yes, when you take that nipple off and look inside, you will either see a screen or a bunch of crap.  The screen only sits back in there maybe 3/8".  If you find the screen is clogged, do yourself a favor and pull your fuel tank and have it boiled out.  Also put on a new filter (or two).  If you have a compressor, start at the fuel pump and blow out all of your fuel lines back to the tank.  Make darn sure whatever is in your system that clogged it up is out of there so as not to have this problem again. 

I wouldnt think you need to replace the screen if you can get it clean with the tweezers.  I would definitely try to clean it out before rebuilding it.  What do you have to lose?



Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: Mongo on February 10, 2011, 11:35:43 AM

A problem I had on my Tracker was that the fuel cap wasn't venting properly, and it would cause bucking at higher rpms.  It actually sucked a dent in the tank!

Loosen your gas cap a couple turns and see if that helps.

Title: Re: Can't get the Sammi to do over 30mph without bucking and stalling
Post by: oak_raid on February 15, 2011, 10:39:56 AM
Well, have you had any luck?