Small Engine Repair Saga (Latest news)

[n2ize]

Here's the latest news on the gas string trimmer that I have been repairing. Just to bring you up to date the problem is that it doesn't take fuel properly. When I press the primer bulb it won't suck gas. If I choke the engine and pill the started enough times I can sometimes get enough gas into it to get it to run for a couple minutes before it eventually conks out. Sometimes if I am running it and I tilt it one way the mixture will run to lean, if I tilt it the other way it runs rich.

It uses a Walbro carbuerator. Just yesterday I rebuilt the carburator, I replaced the screens, welch plugs, regulator needle, diaphragm, gaskets, etc. I also replaced the fuel lines and filter. The result ?? The primer still won;t suck gas and it still runs like a piece-o-shit.

The only part I didn't replace was the check valve that sits directly under the primer bulb. As far as I can see that is the only remaining part that can be causing the problem. Everything else is either new or just like new. Only problem is that I need to figure out if I can just replace the rubber check valve or, if I have to replace the whole cover + check valve. That is about the only part left that can be causing issues with fuel intake. Now, finding a dealer that has these particular parts. Tthey seem to be sort of scarce.

In any event , that is the latest episode of the quest to get the trimmer working again,

[NQ6U]

I just traded my gasoline-powered lawnmower for an electric. $99, couldn't pass it up.

[w2amr]

Here's the latest news on the gas string trimmer that I have been repairing. Just to bring you up to date the problem is that it doesn't take fuel properly. When I press the primer bulb it won't suck gas. If I choke the engine and pill the started enough times I can sometimes get enough gas into it to get it to run for a couple minutes before it eventually conks out. Sometimes if I am running it and I tilt it one way the mixture will run to lean, if I tilt it the other way it runs rich.

It uses a Walbro carbuerator. Just yesterday I rebuilt the carburator, I replaced the screens, welch plugs, regulator needle, diaphragm, gaskets, etc. I also replaced the fuel lines and filter. The result ?? The primer still won;t suck gas and it still runs like a piece-o-shit.

The only part I didn't replace was the check valve that sits directly under the primer bulb. As far as I can see that is the only remaining part that can be causing the problem. Everything else is either new or just like new. Only problem is that I need to figure out if I can just replace the rubber check valve or, if I have to replace the whole cover + check valve. That is about the only part left that can be causing issues with fuel intake. Now, finding a dealer that has these particular parts. Tthey seem to be sort of scarce.

In any event , that is the latest episode of the quest to get the trimmer working again,Position the string close to the Weeds, then keep pulling the recoil really fast.

[n2ize]

Position the string close to the Weeds, then keep pulling the recoil really fast.

Hah !! I was joking about that with my brother a couple weeks ago. We were trying to get it running and I said "just keep pulling the recoil".

[N2RJ]

I have a troy-bilt 4 cycle trimmer. Lasted approximately 5 years. It died this year. I used to drain the carb at the end of the season and fill back with fresh gas but after a while it refused to start. Tried adjusting the valve clearance, no difference. It's getting fuel and an ignition spark but no go. Don't know why.

In the end I bought a new hitachi 2 cycle with a 7 year warranty. I do have to mix gas and oil now but this new unit is MUCH better than the troy-bilt. I had good experience with the brand since I had bought a $79 (A/R) handheld leaf blower.

[KG4CGC]

A 4 cycle motor has a proper carburetor. Usually in the case of lawn equipment, they are simple enough to take apart and clean and reassemble without fear. Jets need a simple soak and then shot through with spray carb cleaner and then compressed air from a can. It will always be the carburetor. If it can't mist fuel and mix air properly, it simply will not run.

[N2RJ]

A 4 cycle motor has a proper carburetor. Usually in the case of lawn equipment, they are simple enough to take apart and clean and reassemble without fear. Jets need a simple soak and then shot through with spray carb cleaner and then compressed air from a can. It will always be the carburetor. If it can't mist fuel and mix air properly, it simply will not run.

While that is true, you need new gaskets when putting it back together. I don't think I can find for this particular trimmer.

One day I'll take it apart and bathe the whole thing in carb cleaner.

[W5GA]

Don't know if this applies to your trimmer or not, Ryan, but I just found out that older Briggs motors have points/condenser in addition to the magneto. Gotta pull the flywheel to get at them.

[KG4CGC]

One important thing, keep the gaskets away from carb cleaner. Keep all the rubber parts away. A little mineral oil (baby oil) and Vaseline™ will rejuvenate old gaskets as long as they're not broken or cracked. Simply remove all residue when reinstalling.

[w2amr]

Don't know if this applies to your trimmer or not, Ryan, but I just found out that older Briggs motors have points/condenser in addition to the magneto. Gotta pull the flywheel to get at them.When I rebuilt my dad's mower I replaced them with a solid state unit, works great.

[n2ize]

While that is true, you need new gaskets when putting it back together. I don't think I can find for this particular trimmer.


One day I'll take it apart and bathe the whole thing in carb cleaner.

If it's a 2 cycle carb and its several years old often the diaphragm needs replacement. They tend to loose their flexibility after being exposed to gasoline over the years. It is also a good idea to replace the metering needle as well. They often have a ribber tip that wears out over time.

If you are looking for parts for your carbuerator you need to find what model carbeurator your trimmer engine uses. Usually it's either a Walbro or Zama carburator. Once you do that you order a gasket/rebuild or repair kit for that particular carb. There are a lot of places that furnish replacement carb parts.

One place you might try is http://www.mowers4u.com . They sell a lot of Walbro carb parts and I am sure they sell Zama too. You might also try http://www.walbro.com or http://www.zamacarb.com/ for information, diagrams, exploded views, parts names and listings, distributors, etc. You should be able to find rebuild kits and diagrams for just about any small engine carb made.

[NQ6U]

Don't know if this applies to your trimmer or not, Ryan, but I just found out that older Briggs motors have points/condenser in addition to the magneto. Gotta pull the flywheel to get at them.

As a former professional B&S mechanic, I can confirm this. Bad points/condenser is probably the second most common problem with Briggs motors after the carburetor, although it's a very l-o-n-g second place. I used to swear that the mechanical engineers up there in Milwaukee couldn't design a decent carb even if someone was holding their grandmother hostage.

Another thing to look out for in Briggs motors is a sheared flywheel key. They're aluminum and are designed to shear off to protect the crank in the event you run your machine up against a rock or other immovable object. Sometimes they only shear half way, which messes up the spark timing and makes the thing run poorly, if it runs at all.

Usually, though, if a Briggs motor is not running correctly, check the carb. 90% or more of the time, that's where the problem lies.

[KG4CGC]

Make sure you get the spray carb cleaner with the straw that attaches to the spray head. In their immense and infinite wisdom, our local WM will only sell one kind of carb spray and it has no straw. It is actually a selling point but the stuff is useless. You need to mate up the straw with the ends of the jets and get the pressurized fluid to blast through. Also, sticking the straw down into the carb body interior channel circuits helps blast out more crud. Be thorough.
The non straw variant is useless for this stuff unless you just want to knock the dirt off the outside.

[N2RJ]

If it's a 2 cycle carb and its several years old often the diaphragm needs replacement. They tend to loose their flexibility after being exposed to gasoline over the years. It is also a good idea to replace the metering needle as well. They often have a ribber tip that wears out over time.

If you are looking for parts for your carbuerator you need to find what model carbeurator your trimmer engine uses. Usually it's either a Walbro or Zama carburator. Once you do that you order a gasket/rebuild or repair kit for that particular carb. There are a lot of places that furnish replacement carb parts.
.

It's a 4 cycle.

[N2RJ]

Make sure you get the spray carb cleaner with the straw that attaches to the spray head. In their immense and infinite wisdom, our local WM will only sell one kind of carb spray and it has no straw. It is actually a selling point but the stuff is useless. You need to mate up the straw with the ends of the jets and get the pressurized fluid to blast through. Also, sticking the straw down into the carb body interior channel circuits helps blast out more crud. Be thorough.
The non straw variant is useless for this stuff unless you just want to knock the dirt off the outside.

I have several of them in the garage, mostly with straws, even the walmart one (got carded for that one) Also have a bottle of sea foam at the ready.

[N2RJ]

Don't know if this applies to your trimmer or not, Ryan, but I just found out that older Briggs motors have points/condenser in addition to the magneto. Gotta pull the flywheel to get at them.

It's not a Briggs engine. It's a MTD, which probably means Chinese engine. I'm getting spark and after many pulls it starts but it doesn't give me full power. I adjusted valve clearance, new plug but I'm yet to tear down the carb. It's a TB575SS.

[N2RJ]

I have a craftsman push mower I need to fix too. I suspect the carb is all gummed up.

[KB3LAZ]

My father has used the same weed whacker for 23 years. I hate the damn things. I just push mow the ditch, lol.

[KG4CGC]

If you can look up a diagram online, even better.
In a ventilated area, use soaking solution for the disassembled body. Used to be a product that was a can like a short paint can that had a screen integrated into it so you could lower and lift the parts in the soaking solution.
Haven't seen it in a while but you can improvise with kitchen utensils. I made soaking solution with automatic transmission fluid Type A, gasoline, B-12 Chemtool and regular carb cleaner. Mix in equal parts. Yes, transmission fluid cuts crud. After soaking, spray again with carb cleaner.
I've only been taking apart carburetors for over a year but I've done it so many times now that I can take apart and reassemble the one on my scooter by feel. Tuning requires this in this case. Done a few yard tool carbs to add to the list. Haven't done a car carb. I don't know anyone who has a car with a carb anymore. Scratch that, I did a VW carb a long time ago and a Holley 2 barrel with progressive linkage. Recently it's just a scooter and lawnmowers.
Probably all easier than trying to sync multiple carbs on a car or bike.

[KG4CGC]

My father has used the same weed whacker for 23 years. I hate the damn things. I just push mow the ditch, lol.

Our ditch is more like a ravine.

[N2RJ]

Didn't think about the ATF but I guess it makes sense since it's supposed to keep the trans clean too. I have half a bottle of Honda ATF I was going to throw out but I'll save it for the carb cleaning.

[KB3LAZ]

If you can look up a diagram online, even better.
In a ventilated area, use soaking solution for the disassembled body. Used to be a product that was a can like a short paint can that had a screen integrated into it so you could lower and lift the parts in the soaking solution.
Haven't seen it in a while but you can improvise with kitchen utensils. I made soaking solution with automatic transmission fluid Type A, gasoline, B-12 Chemtool and regular carb cleaner. Mix in equal parts. Yes, transmission fluid cuts crud. After soaking, spray again with carb cleaner.
I've only been taking apart carburetors for over a year but I've done it so many times now that I can take apart and reassemble the one on my scooter by feel. Tuning requires this in this case. Done a few yard tool carbs to add to the list. Haven't done a car carb. I don't know anyone who has a car with a carb anymore. Scratch that, I did a VW carb a long time ago and a Holley 2 barrel with progressive linkage. Recently it's just a scooter and lawnmowers.
Probably all easier than trying to sync multiple carbs on a car or bike.

My car has a carb.

[KG4CGC]

My car has a carb.

Which car? What kind? Is it a mechanical marvel of human engineering?

[KB3LAZ]

Which car? What kind? Is it a mechanical marvel of human engineering?

81 Z28.

[N2RJ]

I had a 93 civic with a carb. No VTEC but good on gas.

[kf0rt]

I had a '76 Accord that had an actual choke on the dash that you had to pull out when starting the car.

[KG4CGC]

81 Z28.

Details dude. Motor, carb etc. ☺

[N2RJ]

My dad's 1985 Datsun pickup had a choke... And a column shifter!

He has a datsun diesel crew cab now. Floor shift and of course no choke (since its a diesel)

[n2ize]

I have a craftsman push mower I need to fix too. I suspect the carb is all gummed up.

So, get busy and fix it. You can find all the parts online. Check out some of the references I posted and Google for tons more.
get that bad boy running again. Start with a carb cleaning and if that don't work do a rebuild. Don't forget to replace your gas lines and filters while you're at it.

Once I finish with the weed trimmer I've got an old Homelite gas blower to fix and a Poulan chain saw to fix.

[N2RJ]

I tried sears, they said they don't carry parts for that old model anymore. I'll start looking online to see what I can find.

I need a new plug wire and probably a carb rebuild kit.