Walbro LMT Carb replacement?

[JonCraig]

I have a Coleman Powermate Powerbase 5000 with a 10HP Briggs on it. Craigslist find, didn't start. Horribly stale gas and carb crud like you'd expect. Carb is a Walbro LMT with numbers 5-4993 stamped on one side, and then on the other side the number "51" is cast into the body just above and to the left of the "W" of Walbro.

Anyway... I disassembled the carb to clean and boy did it need it. The main jet would not come out and it looks like I may have at least partially stripped the brass head of the jet (yeah yeah... I know). I gave it a trip through the ultrasonic cleaner with the main jet still in ('cause I couldn't get it out), then followed that with lots of carb cleaner hoping to get the jet clean enough.

After reassembly, I could get it to hit on carb cleaner at first, then it would run for 3 or 4 seconds (more than it would on just carb cleaner, so it was getting some gas through the carb) then it would hunt/surge for maybe 1 or 2 seconds then die. I repeated this 5 or 6 times, then it wouldn't start at all and I noticed there was a puddle of gas in the bottom of the carb throat.

I'm assuming I have something plugged up that's causing the engine to run really rich--maybe the inlet needle isn't seating. If that was the case, would the gas rise all the way up into the carb throat? Now that I'm thinking about it, I think it would.

My dilemma thus becomes: Do I buy a carb kit w/ new inlet needle and install, only to discover that the problem is also the clogged main jet/emulsion tube that I may never get out? If that's the case, I'm looking at a new carb anyway, so maybe just go there instead of fooling around with the kit. Is there a reasonable aftermarket solution for this application? I'm sure a genuine Walbro is probably pricey, given that it's a $30 Craigslist find.

Or does anyone have any great tricks for getting that main jet out? I'm soaking it with PB Blaster now in hopes that will free up some crud.

Thanks!

--JC

[KE4AVB]

I'm assuming I have something plugged up that's causing the engine to run really rich--maybe the inlet needle isn't seating. If that was the case, would the gas rise all the way up into the carb throat? Now that I'm thinking about it, I think it would.

Provide the bowl is sealed then yes it could and it would the cause of rich burn. Also if your carb has air bleeds if they are clogged it would also burn rich.

Or does anyone have any great tricks for getting that main jet out? I'm soaking it with PB Blaster now in hopes that will free up some crud.

What you need be using is modified hollow ground flat tip driver blade. What I use is one of those 1/4 hex drive quick change bits that many of us have for our electric drills. Sometimes only needs the corners of the hex knock off and other times the hex has to ground off more as well as tip ground thinner. Either way you want an edge to edge fit (just clearing the threads) with tip fitting tight in the slot. With this the hollow grind help prevent climb out and the edge to edge fit gives maximum grip.

In the following image n\umber 1 is a hollow grind while number 2 is what most flat tip are grounded like. Actually tip is more flat than in the image before start it curve outwards. The tip on my large one is .050" thick and about .125" high before it starts it flare out and the other small one is .030" thick.The width of both is just shy of thread area.

[Arkie]

Here is a link to some LMT info:

http://outdoorpowerinfo.com/repairs/bri ... t_carb.asp

[KE4AVB]

Forgot to say that the tool also needs to be straight sided. With them being 1/4" hex you can use a 1/4" drive ratchet and a six point 1/4" socket for more leverage while pressing down on the bit.

I have only had to drill out a couple nozzles to where an extractor would fit to remove the nozzle. One extraction was successful and the other the extract sheared off but was because I used a too small of an extractor in the first place as I was learning how to do it. These were carburetors that other shops had already screwed up and the customer were just seeing if I could repair them.

Just had to remove the nozzle from a Honda carburetor yesterday after removing the jet. It was so gummed in it had to be forced out. Normally they just fall out. This was on an engine that had been sitting for three years. The stabilized fuel had dried up leaving deposits behind. I know I should had keep it running but it was during a time that there were very more important things to do and I am just getting back to the equipment I had for sell.

[JonCraig]

Whelp, I split the whole thing in half trying to get the main jet out. So now I'm definitely looking for a replacement carb.

Will any LMT off fleabay fit? Or do I need to chase a specific model?

Thanks!

--JC

[KE4AVB]

Would the Briggs Model, type and date code numbers to look-up the replacement carburetor as you need the correct main jet size.

[JonCraig]

Gotcha--will get those ASAP tonight after work. Thanks!

[Arkie]

Whelp, I split the whole thing in half trying to get the main jet out. So now I'm definitely looking for a replacement carb.

Will any LMT off fleabay fit? Or do I need to chase a specific model?
JC

NO!

Really have to keep a heads up here, about jet size, choke area, etc.

And few years ago I bought a 72 piece set of wheeler engineering gunsmith screwdriver set, (about $70) the screwdriver bits are hollow ground and very tough steel, several sizes and they can be selected to perfectly fit carb jet slots, and their is also torx and allen. The sides of the bits are ground straight and will not bugger and ruin a screw head (within reasonable torque) if the proper size is selected. A regular screwdriver is wedge shaped and will ruin a jet slot or screw head easily. I bought the Wheeler set for tinkering on guns but if you piddle around with carbs they are also really great. I choose the correct size and if the jet seems really tight and stuck I carefully place the carb in a vise and gently peck on the screwdriver and if no pop loose I try heating the carb in the ultrasonic and try again. If no go I go ahead and run the carb few times in the ultrasonic, test the carb after tagging the holes and if no go I then know that the jet may have been tightened by Bubba previously or corroded in place and has to come out or replace carb. Kinda depressing when the end snaps off the jet, been their done that. I do not put the jets back in real tight (you can feel them bottom then back off and then re-snug) because the brass seems to stick tighter after awhile. Some of the old Model Large Briggs flow jet carbs has to have another jet removed before the other jet will come all the way out and has to go back in correct order.

I got the Wheeler set from Midway usa reloading, but you can do a search and find them elsewhere to compare prices. I think their is a larger set. Here is a link to the set I purchased. (on sale)
http://ads.midwayusa.com/product/223597 ... g-_-223597

[38racing]

Forgot to say that the tool also needs to be straight sided. With them being 1/4" hex you can use a 1/4" drive ratchet and a six point 1/4" socket for more leverage while pressing down on the bit.

I have only had to drill out a couple nozzles to where an extractor would fit to remove the nozzle. One extraction was successful and the other the extract sheared off but was because I used a too small of an extractor in the first place as I was learning how to do it. These were carburetors that other shops had already screwed up and the customer were just seeing if I could repair them.

Just had to remove the nozzle from a Honda carburetor yesterday after removing the jet. It was so gummed in it had to be forced out. Normally they just fall out. This was on an engine that had been sitting for three years. The stabilized fuel had dried up leaving deposits behind. I know I should had keep it running but it was during a time that there were very more important things to do and I am just getting back to the equipment I had for sell.

with the hex end would using a hand impact on it work or would it tend to split the brass even sooner?

[KE4AVB]

with the hex end would using a hand impact on it work or would it tend to split the brass even sooner?

Don't know never tied it. I only dealt with one split nozzle and it was because water froze in the carburetor and wasn't me that split it.