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Lucas B&S engine searching

Started by Don P, December 12, 2017, 08:32:45 AM

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Don P

We've got at most a couple of hundred hours on this engine and it has not been fun for the past 150 or so. Weve cleaned the carb and jets several times and opened the main jet about .005 still it will not settle down , the gov is constantly searching. A visitor who stopped by to watch the mill noticed the governor spring was not doing any work so we bent the tab a bit to give it some tension, didn't help and we returned it to original position. Ideas? Short of that has anyone put a Honda on one of these?

Kbeitz

Some briggs has adjustment on the governor rod that goes into the engine.
I'm not sure about your engine,
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Hilltop366

I'm sure you checked the air filter but I thought I would but it out there, also a non oem filter or not replacing the foam over the pleated filter (if equipped with one) may cause a lean condition?

Got me wondering what changed at 50 hours?

Don P

There wasn't a sudden degrade it's just getting worse and worse. We've cleaned and blown out the filter often.
Actually clogged I think it would choke and richen up the mix but it could sure foul up any adjustments, which are pretty much fixed or plugged on this 10 cent carb  :D

I like the governor rod idea, need to look for adjustment there and chase that mechanism from end to end for trash I guess.

Kbeitz

This is the rod I was referring to. loosen the clamp and turn the screw.



 
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Hilltop366

Ya I was thinking too much air more than plugged filter, I've seen some push mowers that won't run at all with out the filter.

Does it surge at any engine speed? Only after working hard or all the time?

Does it have a fuel pump or gravity feed to carb?

Fuel filter?


Gearbox

There is 2 Grey wires tied together with a diode in each leg . If one of the diodes goes bad it will run bad may cause bad spark plugs . They can be tested I think I just replaced the one bad diode .
A bunch of chainsaws a BT6870 processer , TC 5 International track skidder and not near enough time

TKehl

Sounds like it may get sorted out, but my Lucas has a Honda on it.
In the long run, you make your own luck – good, bad, or indifferent. Loretta Lynn

Crusarius

air leak in the fuel system? My zero turn does the same thing and I am pretty sure it is because the o-ring down in the bowl is cut allowing air leakage. Runs fine with a load but without a load it surges terribly.

sawguy21

Hold your finger on the throttle shaft, if it smooths out the governor is too sensitive and needs attention. If it stumbles and dies it is either starving for fuel or has an air leak. What is the model number? It will give us a better idea of what you are looking at.
Crusarius, you have a problem in the idle circuit. An air leak that bad would cause it to die under load.
old age and treachery will always overcome youth and enthusiasm

Crusarius

Thanks sawguy. now if only I knew something about carbs :) I know I need to reseal it cause that o-ring is history.

Don P

Thanks for the replies, I'll charge up the camera and go get some pics tomorrow if I can get over there, we are steadily deteriorating outside. It has a fuel pump, 18 hp B&S Vanguard twin, I'll get a shot of the spec plate. It will not idle and is searching load or no load. It does smooth out with a finger on the throttle shaft. It doesn't have that adjustment on the governor that I've found, I have had that on older engines.  It was missing at the end the other day. The air filter I think is ok, there was a trace of dust but I don't think that is it. This thing should be too new to need adjustment I would think. The air leak has me thinking.

Kbeitz

If it's hunting or as you call it searching load then the governor is working.
Most of the time your problem is with the low idle jet plugged.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

sawguy21

The governor is too sensitive. There should be several holes on the governor arm that the spring can hook into, move the spring to the next outboard hole and reset the governor. With the engine off, loosen the clamp bolt and turn the throtttle shaft from idle to the wide open position. Now with pliers turn the governor shaft in the same direction and without disturbing anything tighten the bolt. This is the static governor setting.
With the engine running, hold the throttle against the stop screw and adjust to 1250 rpm +or - 50. Let it go and adjust the idle screw on the throttle plate to 1800 rpm. Now open the throttle to full speed and bend the tang on the governor spring to around 3300 rpm, don't go over 3600.
old age and treachery will always overcome youth and enthusiasm

Dakota

My Lucas has the 18 B&S on it.  It started running real rough a while back.  I finally figured out that I had been putting fuel with Ethanol in it.  Got the right fuel in it, and it smoothed out in about 10 min.
Dave Rinker

Don P

Really, wow. We've been running 93 with ethanol, I'll have to pick up some real gas, that's a pain. I put one of their 19 horse one lungers on the mower this year running the cheapest gas and it does fine, totally different engine though.

I'm dallying hoping the wind will die a bit. That windy cold is to the bone. I went over this morn the camera I think has died or its smarter than me and wants to stay inside  :D. Its a 570cc 2014 model 18hp B&S vanguard twin cylinder engine, the clock says 146 hrs.

Reading more googles, check vents, that's quite possible. Not being able to Idle might mean it is sucking hard, dunno. I've printed a B&S carb troubleshooting guide and sawguys governor tuning. Its gotta be trash somewhere, this thing is too new. The forums are full of these things surging though, (that might be true if you look up surging for any small engine). Failing that I'll clean the carb again and get the glasses and good light, I pushed a tip cleaner through everything I could find, tons of cleaner and blower. It doesn't take much though.

jwilly3879

My Honda on the splitter will do that unless I run about 1/2 choke then it is fine. Have cleaned the carb multiple times, messed with governor springs, etc but figured 1/2 choke was easiest and it runs fine that way.

Don P

When it first started that would help. The other day it wouldn't but it was surging much worse. I cleaned it out again and may have gotten some trash out, my eyes are not that grade anymore, I had readers and a magnifying glass out. I think I saw something, ran a tip cleaner through it and carb cleaner and blower then I didn't see it anymore, then again it could have been one of those old dude eyelashes fell into my field of intense view :D Buttoned that back up and brought the tank home and am draining it. There is a filter on the underside that I don't think either of us has ever touched. But while I was draining the tank, I just stuck the fuel hose in a gas jug and opened the gas valve on the tank, gas trickled out. I cracked the cap on the tank and got a stream. I never thought to try to crack the gas cap while it was surging, it is an unvented tank though.

starmac

The tank has to vent somewhere, I would imagine it is through the cap.
Old LT40HD, old log truck, old MM forklift, and several huskies.

breederman

I fought with a friends  lawn mower half of the summer . It would surge for a bit then quit.  That turned out to be a plugged vent in the cap.
Together we got this !

Don P

 :D Wouldn't that be simple! I'm off to PT, I'll pick up new gas and head over there to finish reassembly and a trial run. Dang, it's still blowing 50+ outside, getting old  :D

Don P

I cleaned out the tank and filter and found the tank vent, cleaned it up and blew it out. It goes to a tube and what I assume is a charcoal block in the air cleaner cover. I lightly blew into it and water came out. Finished reassembly and the surge was gone. It runs a little better with the cap cracked so that canister must be shot. It's overrevving a little but I'll let my partner, the saw's owner, do the governor tab bending to get that reset. Idle is still a mess but the governor at the current point is not fully out of the loop at that point. He'll be back Sun, hopefully we'll be able to make some dust Mon. I'll know more then but I think the problem the whole time has been a clogged vent.



This is the governor rod, vertical


And the spring and tab, on the left, that was bent a little tighter to the spring. There are no other holes. This is different than ones I've messed with, bending that tab is apparently the adjustment on these. It's running about 3750 now and it isn't really cut out at idle position so I think just a bend back while watching the tach and hopefully idle will clean up.



Thanks for all the help and suggestions. I find my mind gets stuck in a loop with stuff like this. If you're cleaning out the carb for the fourth time, it probably ain't the carb. My lesson here is if it surges open the gas cap and see if it levels out.

Don P

Wow, we've been off awhile playing in the warm shop. Swapped the Deutz engine in the loader, worked on multiple vehicles and did carpentry and frozen plumbing, and played with this swingset and winch for the Lucas so we can quickly spin the powerhead around and cut double width, takes about half a minute and no back strain. Needs a little fine tuning but we're winning.


But the engine still has a problem, hoping for more ideas. We bent the gov spring tab back to 3600. It isn't surging any more but it won't drop down to a good idle and really lacks power under load, I was nibbling that red oak. Fuel pump seems to be throwing a good strong stream. We stuck a vacuum gauge in the dipstick hole and got a pulsing pressure, up to around 5psi. I expected a slight vacuum. its an 18hp vanguard twin, I'm still looking for a service manual if anyone has a link, the operators manuals aren't much.

Dakota

Don, I have the 18 hp Briggs & Stratton on my Lucas.  I think this where I got my service manual:

Main site is:https://www.briggsandstratton.com/na/en_us/support/user-community/customer-support/obtaining-support-documentation/repair-manuals.html

service/repair manual is: http://bit.ly/1Tz1B8D
Dave Rinker

Don P

Thanks for the link Dakota. We got the manual and talked to one of the tech guys while I was wrenching in the garage. He pointed to the carb or valve adjustment which we did but it didn't clean up idle and was down on power. We did a cold compression test and had one cylinder 30 lbs lower than the other so pulled that head and found no problems, checked the valves for leakage with air and carb cleaner but the seats seemed to seal well so a new head gasket, reassembly and the cold compression had not changed 120 and 150. A little oil down the plug hole didn't change it, repeated both 3 times. The cylinder walls look pristine, cross hatching is still there and looks factory everywhere. So after tearing the carb down and cleaning it out 10 times, we decided there was trash somewhere we couldn't get to, ignored the cold compression, and ordered a new carb. That was it. We had the blades retipped and tensioned and it's cutting better than new  8). Soo, we'll watch the fuel and air filters better. The old carb is in a long term soak and we'll get a rebuild kit and new jets for it. I'll pop the welch plug out and run wire through that area. The Nikki carb is sort of disappointing. In the manual they show a typical idle mixture screw with a spring under it then a limiter cap. There was no spring so the cap was the only holder. The new one is a step cheaper it looks like, it is all behind a plug inaccessible and unadjustable. Basically they are throw away carbs. Had to kind of laugh, I've slapped a new Edelbrock on the truck without a thought but this simple little one barrel wasted a whole lot of time, it also cost half of what a 4 barrel does, or, about 1/5 the cost of a new engine. If someone finds a cheap source please holler. We'll run it awhile and next time we have some loose time and are caught up will check compression warm.

Next question, my bias is going to show, I kinda doubt this is a long term hard working engine and don't want to throw a whole lot at it. It is a good bit lighter than a equivalent Honda. The mill frame and components are pretty tight around it. Has anyone swapped out a Honda on one of these mills?

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