Gas Trimmer Dies Right After Starting


Old 11-07-04, 07:55 PM
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Gas Trimmer Dies Right After Starting

I got this gas trimmer at a garage sale. It is an old, im guessing 8 years old, gas trimmer made by IDC. It has a diaphragm carb. Anyway, as per label starting instructions, I press bulb 5 times, hold down trigger, switch to full choke, yank cord 2-3 times, switch to half-choke, yank 3-4 times till it starts, warm 5 secs, them switch choke off. Well, its starts OK, but dies like 2 seconds after starting. It doesnt matter whether Im revving it my having the throttle held or are letting it idle. It just dies. Im dont know a whole lot about trimmer repair, but I got this thing real cheap, so I won't feel bad if it is a piece of junk. Im guessing though this should be an easily fixed problem? I dunno. Oh the model #, its a 780 Series by IDC. Anyway, any help you are able to offer would be greatly appreciated!

Last edited by Jason17; 11-07-04 at 09:49 PM. Reason: more info
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Old 11-07-04, 08:01 PM
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Sounds like the gas pick-up tube may be broke or missing. If it has a sem-clear tank you may be able to see it. The trimmer seems to be running only on the gas put in by the primer button. Check this out first. Good luck and post back.
Old 11-07-04, 08:03 PM
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Hello Jason!

There are 2 screws side by side on the carb. The one closest to the air filter is the high speed screw. Try unscrewing it about 1/2 turn or so and see what happens. Although it probably has other problems, it's worth a try. There are a number of things that could be wrong...mostly dealing with the carb or fuel lines. IDC, to say the least, was not known for being quality equipment if you know what I mean.
Old 11-07-04, 09:47 PM
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majak: Ill take a closer look, but Im pretty sure the fuel lines are OK, because I had to replace the fuel line for the primer button because it had cracked. The other lines looked like they had been replaced recently, but maybe its clogged, I didnt check.

cheese:I'll try that tomorrow, any other ideas would be appreciated too! BTW, I didnt know that about IDC, I guess thats why you dont see them around anymore! LOL! Anyway, I used to have an IDC electric trimmer for a long time, worked great for wacking those weeds and lasted a long time. Motor went last year so I bought a Homelite electric trimmer to replace it. Works great too. But when I saw this gas one, I thought what the heck, if it works, its easier than dragging hundred foot cords around! I guess quality is more important with gas though. Ill see if I can fix it without too much expense, if not, Im not out much.
Old 11-11-04, 03:37 PM
Brian Humphrey
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IDC 580 supreme

I have a very similar problem. This one I bought new (many years ago) it has been very reliable for many years. It has set idle for 2 years, using an electric trimmer, I decided to spend some quality time on it to see if I could get it working. I found the fuel lines and primer bulb were rotted. Unfortunately I did not remember how they were plummed. I bought new fuel lines and primer bulb. I installed them (one line from tank to primer bulb input - this line does not have a 'filter' on it), the ouput line from the primer bulb goes to the 'top' of the carberator. The other line goes from the gas tank (this line has a filter on it) to the bottom of the carb. I am not sure it this is the correct way to plumb it. So I now have the same symptoms, I can press the primer bulb and it will start for 3-5 seconds then stop as soon as it seems it is out of gas(it does not keep pulling fuel, although the line is full of fuel). I tried to experiment by moving the line from the primer bulb output to the bottom of the carb, and the other line from the tank to the top of the carb. After doing this the trimmer would run normally (idle and rev, ok) however I notice that once I shut it off , fuel would drip from the carb. I don't think this is the way it should be plumbed but it proves the engine will run if it has fuel. I would like to understand how it should be plumbed, then figure out what the problem is from there (I have read some FAQ's that indicate maybe the carb needs rebuilt, because of age the carb cannot pump fuel through). Does anyone have any suggestions??
Old 11-11-04, 05:02 PM
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with both lines off of the primer, push it, the hole that blows is output and goes to the tank with no filter.
Release the primer, the side that sucks is in, the line from the top of the carb goes here. The filtered line from the tank goes to the bottom of the carb.

It most likely needs a kit for the carb, especially if it sat and a chance it had fuel in the carb.
I dont know anything about IDC least not by that name but if its a walbro or zama carb, the diaprams should be no problem to find and only a few bucks.

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