Hi All,

I've a 4 stroke strimmer that I bought in the US. I seem to have a fuel starvation problem. I can get it to run briefly on idle. As soon as I squeeze the throttle, it dies. This happened after having used it once. I took it to my local strimmer emporium, who charged me a fortune to "CLEAN THE CARB OUT", and the problem has returned after having used it once more. Reluctant to go back to the same guy, I've stripped the carb, cleaned it all, checked both fuel lines, (there is a return line to the tank) and still can't get it running properly. Can any of you give me any advice?

TIA, Ian.

Are there mixture adjustment screws on the carb? There usually are.

Find the main jet one and richen it up. If it makes it worse, make it a bit leaner. 1/2 a turn at a time and make sure you remember where it started off.

like the new avatar David! hubba hubba!

I'd go along wuth David on this one I had a chain saw that used to do similar things.
I had to adjust the mixture each time I used it.
Never did figure out why.

The only visible adjustment is an idle screw. It's designed for California's emission laws so probably tamper proof!

A few random thoughts...

If it has a return line, does that mean it has a fuel pump? If so, is it working? IMHO, it sounds like you have enough fuel for tickover, but not enough to run.

If it does have some sort of fuel pump, is there a restrictor on the return side of the carb inlet? (there should be)

Does it have a fuel filter? I guess you'd have checked that!

Does it have a starting choke lever? If so, is it in the wrong position, or broken?

Little engines can foul the plug is they don't start properly - might be worth a check.

Does it have any timing adjustment hidden away (I wouldn't expect it to, but you never know).

End of random thoughts... I still suspect fuel starvation...

David

I think you're correct on the fuel starvation thought.

1) There is a fuel filter in the tank.
2) Not sure about the restrictor on the return line. It's a different colour pipe so possibly a smaller id.
3) It must have some sort of pump, as fuel spurts out of the return line.
4) The choke works.
5) I've checked ye old spark plug.

At a loss. I've e-mailed the manufacturer, but don't expect much joy. There are no adjustables on the carb. So I'll put in back in the shed, and have a go at it tomorrow!

One thought - when the carb was cleaned out, did you change the fuel & clean the filter at the same time?

I'm just wondering if you've got a batch of dirty fuel that keeps throwing much in the jets.

David

Does it keep running if you open the throttle very slowly?

Check the little rubber vent valve in the fuel cap. They commonly stick if unused for any period of time.

is it a walbro carb?

if so the diaphram could be on its way out...

Dont American machines use fuel faster than ours because its cheaper?

You have yank fuel starvation problem there my friend.. If you dont yank it so often you get more out..

have you replaced the fuel, as it does "go off" if its left stood for a while.

Ray

Not meaning to be funny but does it have choke??

If so is it working? It might make it underfuel when its cold so would give u this affect??

Probably talking complete coblers but worth a try. Chokes are funny things.

i have converted petrol engines in one of my RC Aircraft....these use the Walbro carb.....

just a thought....check the fuel line in the tank, it may be split just as it exits the tank on the inside.

also check the pick up aswell.