Weed Eater GTI-16 Gas String Trimmer

My uncle donated his old 2 stroke gas string trimmer to me when he found out I was looking for one. I finally got sick of dragging out two extension cords to try and reach the front and the back of the lot.

He had a Weed Eater GTI-16 sitting in his shed for the past 2 or 3 years. It looked like it was in pretty good shape, the starter rope extended and the trimming line turned as the starter rope was pulled out. I didn’t try to start it since I wanted to check and lube the shaft first before it got up to speed. The engine probably would have fired up without any work though.

This time my adopted small engine came with an owners manual that covered the GTI-15T and the GTI-16. I had some basic instructions to work off of – how to tune the carb, replace the starter cord, etc.

The basic plan was to:

  • Lube the drive shaft
  • Rebuild the carburetor since I was going in to see how the diaphragm and pumper valves were anyway
  • Replace the fuel lines and filter
  • Clean everything up and lube the air filter
  • Check the spark plug


Most of the fasteners on this machine are hex screws and nuts. I used a #4 hex wrench I had that fit but these are probably imperial hex heads.

First separate the engine from the shaft. Two hex heads with the locking nuts self contained in the green plastic shroud hold on the shaft.
Set the shaft aside somewhere clean – I hung it from the handle on a nail in my shed.

Find a nice big work surface that can get dirty with oil and gas for all these little parts you are about to take apart or cover your work area in plastic and newspaper.

Have some carb cleaner, rags, nitrile gloves, a rebuild kit for your carb (check model number!), fuel filter and fuel lines from the small engine repair store. Cliffs Lawn and Garden in Oakville were my part store of choice again as the two other stores I tried near me were closed. You can find a list of Poulan Pro distributors which carry weed eater parts on their website then click on support and enter your postal code in the ZIP textbox field.

First thing is to drain out any old gas from the tank – it’s going to smell like varnish and there will be some in there. There always is.

Disconnect the spark plug, remove it and replace it or give it a clean, re-gap it and set it aside. Now you don’t need to worry about the engine starting up while you work on it.

You’ll see two connections to the carburetor. The throttle wire and gas line. Pull the gas line off the carb and remove the screw holding on the plastic bracket for the throttle wire — you might not need to do this I found it makes it easier to disconnect the throttle wire.

Now remove the tank from the engine by removing the bolt on the handle near the shaft and then slide the tank back over the springs near the carb/exhaust moving away from the carb. Inspect the rubber shoulder on the shroud for tears and replace as required. Take a picture or note which hole the throttle wire connects into. Disconnect the throttle wire.

Unbolt the air filter using the hex wrench. It will have markings for the choke on it – not the exhaust cover which is a plastic mesh and probably has oil all over it. The plastic plate will come off and you’ll see a sponge filter. That is the air filter. Clean it with soap and water and let it dry over night. When you go to reinstall the filter, put a few drops of two stroke oil on the sponge and smush it around with your fingers.

You’ll see a sliver plate with a leaver on it and some oil/dirt — this is the choke plate. The lever restricts air flow into the carb on cold starts. Remove this using the two hex bolts that bolt through the carb. Be sure to keep the gasket between the carb and the body of the engine (green plastic) in tact as this part is not in your carb repair kit. Remember which bolt has the lever on it, I removed the assembly together, cleaned it with carb cleaner and set it aside.

You’ll now have the carb in your hand free from the engine. Don’t lose that gasket between the carb and the engine but do clean it up. At this point I’ll pass off the rebuild of the carb to the pros. See the links below for assembly diagrams, how the carb works and instructions for rebuilding. If you aren’t comfortable working with small parts and going slowly matching up parts from your kit, take it in and have someone else do it. The rebuild wasn’t very hard but the two parts I noticed that were not in my rebuild kit were:

  • The metering spring under the metering lever which is attached to the fuel inlet needle – if this goes flying during disassembly good luck finding it
  • The seat for the fuel inlet needle – but it does come with a new needle. My lawnmower kit came with a new seat washer – maybe I lost it when I opened the package.

Be sure to check how many turns the screws were out so you can reset them after the rebuild. Here are some photos of my carb when I was working on it. My carb was a Walbro 207A – it’s stamped on the side. Use a flashlight and a rag to find it near the big screw.

Fuel System Replacement

The hardest part of this was replacing the fuel lines and filter.
Fish the old one out of the tank, it will be in there with about 6″ to 8″ of line and a filter on the end of it. I was replacing everything so I just pulled it out of the fuel filling hole in the tank. You may just want to replace the filter, depending how dirty the system is.

The new fuel line is really stretchy and you’ll have a hard time getting it through the hole in the gas tank. This is a “through wall” line so the line itself seals off the tank. You’ll see the bump in the old gas line where it went through the tank wall. I tried pushing it though with an angle cut on the line as the installation instructions said. That didn’t work, the fit was so tight I couldn’t push it through – the line kept collapsing on itself.

What I ended up doing is cutting about 3 to 4 inches of line in half the long way. You can’t just slit the line, you actually have to remove half the lines material so it will easily fit through the opening in the tank. Now you’ve got a half line tag to grab with a pair of needle nose pliers. Pull from the top with the pliers while pushing the line through from the bottom to feed the line into the tank. Once you are able to get the original length or longer though the tank (3-4 inches) that isn’t cut out cut the line straight so you can install the fuel filter. This took me about an hour to figure out – hind sight is 20/20.

While pushing on the fuel filter don’t just try to push it on. Once you get it started push and rotate it at the same time. I also used my needle nose pliers to try and stretch out the end of the fuel line. It was a really snug fit.

Drive Shaft Lubrication

Lubricating the drive shaft is very simple. Cover the bench in fresh newspapers – clean is important here as dirt will cause problems at high speeds. Pull the drive out of the shaft and set it on the newspapers near the top, not in the middle. Check for broken wires in the drive and then wipe down the drive shaft cleaning off any dirt or old lube. Set the drive shaft down on the lower clean section of the newspaper. Now pull out your handy white lithium grease spray can and douse the entire drive. Flip and do it again. Then reinsert the drive into the shaft. Spray some lithium grease into the shaft and reinstall on the trimmer to keep dirt out of the freshly greased shaft.

Reinstall the spark plug and pay attention that the inside spring of the wire fits snugly over the plugs metal boot. If you’ve twisted the plug line it will rotate in the plastic boot and not make a good connection.

Mix up some new fuel with oil in a 40:1 ratio and fuel the machine. Cross your fingers and pull for quite a while. Then attempt to tune the engine using the idle and mixture screws.

I found the choke doesn’t really work that well. I just kept on pulling – something like 15-20 times – before I heard the engine try to start. I had the choke on, once I took it off she fired up. I can’t seem to get the choke to work that well, but after enough pulls the fuel pump must fill up enough to start the engine. Update: I’m going to hope this one is operator error. I re-read the manual section about starting the engine and I didn’t open the throttle (pull the trigger) when trying to start. This makes sense as the snow blower needs full throttle with the choke on to start up too.

When the engine is warm it doesn’t have any problems starting with the choke off.

Direct drive or not? I think this machine is a direct drive – ie, no clutch. The manual talks about the cutters not spinning when idling but all the exploded drawings of the machine do not show a clutch plate. I think this machine is direct drive which is ok with me. That means I can trim at idle and high too! Just be careful as the cutting lines will always be spinning.

The only way to know for sure would be to open up the engine shroud and look for a clutch just in front of the fly wheel. I’ll wait until I have to replace the stater rope or fly wheel key before I bother with that for now though.

Links

  • GTI 15 1992-07 Parts List I wouldn’t use these part numbers though as it isn’t the 15T described in the manual. Just shows the general assembly diagrams.
  • Walbro Carb Manual – Official Carb Manual, explains how it works, exploded diagram and parts list, flooded starting, rich and lean tuning and maintenance (rebuilding instructions).
  • Carb Details PDF – 3rd party explanation of the carb and how to rebuild them at this website

Update:
The string size used in this trimmer is 0.080″.
Spark plug gap is 0.025″ or 0.635mm
The Poulan Pro Customer Support rep provided me with the GTI 16 IPL document.

11 Responses to “Weed Eater GTI-16 Gas String Trimmer”

  1. Weedeater Parts Says:

    This is a pretty awesome weed eater guide!

    It’s quite refreshing to see that there are other people who take care of their equipment. I’ve had so many emails about broken this, and broken that, and all of them could have been prevented with some simple maintenance.

    Anyway, awesome read man!

  2. scott Says:

    Hi I just picked up one of these at a yard and this guide will be of great help to me. It runs I gave it a little clean up. I was wondering if you saw the engine displacement while you were doing the rebuild. I don’t see a clutch in the diagram and it spins at idle, actually works well at trimmer at idle. A nice find that will hope last me a few years with a little TLC. I will try to find a card kit for a winter project. Thanks for the great article.
    Scott

  3. Steve Says:

    Hi, thanks for the step-by-step! I actually made to the end prior to reading, however, I still can’t get mine to start. I took it all apart and sprayed cleaner. I replaced the fuel line and filter and it appears to be working, but when I spray some starter fluid into the carb, it fires up but for only the amount of starter fluid that was in there. That tells me that the spark plug is ok and it is in the “on” position, but it won’t keep running? Any thoughts? Thanks in advance! Steve

  4. Nesser Says:

    Steve, I’m not an expert – not even that experienced. Just a computer programmer but I’ll take a shot.

    You’ve eliminated spark as being a problem. I’d also say that if the starter fluid is running the machine it seems to be able to breath. The basic things needed for combustion are fuel and air in the right ratio with a spark.

    Be sure you’ve opened up the choke to the running position at the top which is directly under the gas tank. I don’t think air is your problem though.

    Try removing the spark plug over night to let it and the combustion chamber dry out from any starter fluid and fuel. Then try starting it 8 or 10 pulls the next day. Take the plug out and see if has any fuel on it.

    • No fuel on the plug is a dead giveaway that something is up with the carb and fuel isn’t getting into the combustion chamber.
    • If there is fuel I don’t know how to tell if it is too rich or not (flooding the engine). If you do see fuel try adjusting the carb screws to the factory default suggested – I think it is about 2 turns back from tight – careful not to turn the pins too tight hitting bottom. Specs are in the Walboro Carb Manual link depending on what model you have. Then tune from there according to the weed eater manual.

    If these don’t sort it out you may have installed a gasket in the wrong orientation.

    Check out the “Carb Details” link for lots more info and some common mistakes. It is really detailed but take some time to check it out. I just updated the link since it was revised in June 2010 by Lynn W. Graves. There is a new section on the first page in red that might relate to your problem.

  5. Ron M Says:

    On my Weedeater GTI 16 Super model line trimmer I have lost the fitting at the bottom of the fuel tank where it exits the tank and accepts the fuel line. There is no part replacement available that I can find.
    Help

  6. Nesser Says:

    Ron,
    Start with the parts guys at your local poulan pro approved dealer. See instructions in the post above for finding them. If you don’t get good results with one shop, try another one near you.
    http://www.poulanpro.com

    If that fails try to find a similar model that is broken and/or cheap either online or at a garage sale that has the part or the fuel tank assembly intact. You’re basically looking for a parts donor machine. But you might get lucky and find one better than what you’ve got.

  7. charmain Says:

    I have picked up my dad’s gti16 weed eater. my dad is not in the living. the spark plug is missing. I have no model no for this part. can you kindly let me know the part no please.

  8. Nesser Says:

    The manual says the Spark plug is a Champion (RCJ-8) with a spark plug gap of 0.064cm or 0.025″.

  9. rich Says:

    trying to locate a fuel tank assembly for my GTI 16 part#530029552. My mechanic lost it. I cant run the machine without it. any help would be appreciated.

  10. Nesser Says:

    Rich, if you can’t find the part locally through a shop or the manufacturer since these are older machines. The next best thing is to find a similar machine someone is retiring/selling/upgrading and use it for parts. Usually the carbs are gummed up but the fuel tank should be fine. Check your local online ads as people start cleaning out their garages this spring.

  11. Scott Says:

    I just found a pdf of the original manual, a lot of good info. Also just ordered a card kit and plug. Too good a unit to not repair and keep using.
    PDF http://lawnandgarden.manualsonline.com/manuals/mfg/weed_eater/gti_16_super.html

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