Got a Stihl 028 AV that's sat in a basement for at least a couple of years. Has good compression, but wasn't getting fuel to the carb. Removed carb, disassembled and cleaned thoroughly, replaced the diaphragms, gaskets and needle valve. All screens were clear. Replaced carb, still not pumping fuel. Found a tear in the fuel line, replaced line and filter. Still no fuel, but fuel flows through the new line if I slightly pressurize tank. OK, must be the pulse line from the crankcase to the carb. Replaced pulse line, knew I had to have it fixed!!! Low and behold.....still not getting fuel to the carb.. Been working on chainsaws and other small engines since I was a teenager working at the Western Auto....this ones got me stumped!! Any ideas? Thanks!
Stihl 028 AV fuel woes...
- Thread starter JimB
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Well, you've done about everything fuel wise if that's a new carb. I assume you have a good spark. Remove the plug and try adding a teaspoon of fuel directly to to the cylinder. Replace plug and see if she fires after one or two pulls.
Thanks for the reply. Blue spark jumping the gap on my tester. Will start when gas is squirted in cylinder. Carb isn't new, but has new diaphragms, needle valve and screens are all clean. Done probably hundreds of Tillotson's and Wabro's over the years. Can't help but think the carb isn't getting crankcase pulse, but the only thing I haven't changed is the crankshaft seals.
I assume you blew through the lines prior to installation..sometimes you get a reject.
I thought you said "new carb". Forget the crankshaft seals. That's not it. I think your carb is toast and can't deliver fuel to the cylinder. Sometimes even rebuilding fails, but you might want to try that route again. New carb runs about $35 shipped. Only other possibility is complete loss of compression, but if it fired after a fuel squirt, that's not likely.
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Where can one get a carb for $35?
It's out there. Advertising for someone else here is frowned on. Rules are rules.
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Just curious, I have been looking.
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I see a bunch of used ones for $35.......
I also suspect you have a bad carb. (you said it briefly runs with a squirt of gas.
Take the carb apart on a good lighted work bench and if you don't have a ultrasonic cleaner bath use some very warm water mixed 50/50 with white vinegar and let it soak for about 2 hours then blow the passages two or 3 times during the soak with low pressure air and run a tag wire into any small holes. I had a similar experience with a chainsaw carb awhile back and finally noticed that their was a small welch plug completely gone. Suspect it went away when using too much air to clean the passages or it was part of the problem due to being loose not sealing properly. Also make sure the gaskets and diaphragms are in correct stacked order. Check the needle valve area again for correct lever height, etc and look at exploded view of the carb on-line. (for assembly pointers, etc) Suspect is has powdered aluminum corrosion internally blocking one of the small passages. The white vinegar will eventually loosen or soften the internal corrosion without eating other parts.
What is the make of your carb?
Try flea bay for a carb. Might be a generic clone, but it will give you an idea if you have a clogged carb.
When I know for sure the issue is a carb I can usually repair the carb with time and patience.
Here is a new 028 carb on flea bay. I think you can beat this price with some careful shopping.
180592697419
Take the carb apart on a good lighted work bench and if you don't have a ultrasonic cleaner bath use some very warm water mixed 50/50 with white vinegar and let it soak for about 2 hours then blow the passages two or 3 times during the soak with low pressure air and run a tag wire into any small holes. I had a similar experience with a chainsaw carb awhile back and finally noticed that their was a small welch plug completely gone. Suspect it went away when using too much air to clean the passages or it was part of the problem due to being loose not sealing properly. Also make sure the gaskets and diaphragms are in correct stacked order. Check the needle valve area again for correct lever height, etc and look at exploded view of the carb on-line. (for assembly pointers, etc) Suspect is has powdered aluminum corrosion internally blocking one of the small passages. The white vinegar will eventually loosen or soften the internal corrosion without eating other parts.
What is the make of your carb?
Try flea bay for a carb. Might be a generic clone, but it will give you an idea if you have a clogged carb.
When I know for sure the issue is a carb I can usually repair the carb with time and patience.
Here is a new 028 carb on flea bay. I think you can beat this price with some careful shopping.
180592697419
Did you remove the welch plugs? I only do them as a last resort--and it sounds like that's where you are.
Thanks again, compression is very good. Fuel is in fuel line, but carb is bone dry. Needle valve is free and lever is set correctly.
Tillotson carb. I don't think the problem is in the metering of fuel, but getting the pump diaphragm to bring fuel to the carb. The carb is dry every time I've disassembled it. Going to put a vacuum/pressure gauge on the impulse hose tomorrow and make sure the carb is getting signal from the crankcase.
Big_Wood
westcoast dweller
on some of the newer kits there is 2 diaphragms needed on the pump side. one will be the actual diaphragm without the check valve flaps on it and the second will be one with the check valve flap but with the diaphragm cutout. it's important to make sure the one with flaps is against the carb body, then the on with diaphragm, gasket, and then cover. even with them mixed up fuel should still make it up the line though. if you forgot the one with the diaphragm altogether she flooded to piss cause it would be dumping fuel down the impulse line. if you forgot the flap one it would do as you are saying. or you may have got a kit with the diaphragm and flaps on the same piece? more info needed but that's all i can think of if it's not pulling fuel into the carb.
albert
Addicted to ArboristSite
Are you sure the needle seat opening is clear? This is between the round screen and the needle. If you remove the metering side cover and diaphram and attach a length of hose to the fuel barb, you should be able to easily blow thru the hose when depressing the metering lever and hear the air escaping @ the needle valve.
KYsawman
Mr XL-12
If you need a new carb to try send me a PM I have a good used tillotson for a 028
smokey7
jack of a lot ace of a few
Is it running now then? Usually if the carb is filling the line it's pumping. Now it may not be metering properly still tho. Please let us know how it all turned out. Sounds like it needed a fuel line and a intake boot for sure, but may not have needed the carb kit. Now you know where you are at.
Thanks for al the replies! Fuel line was full because I pressurized the fuel tank slightly. Carb kit was probably needed, diaphragms were pretty stiff. Intake boot is ordered, will post results! Thanks again!
