I had a Farmertech carb that would not run right at anything over 1/2 turn out on high. Thats why I replaced it with the C3M.
Farmertech 372xp wont hold a tune
- Thread starter Alanmurphy6912
- Start date
Help Support Arborist Forum:
I would step back and vacuum test it again. Cranks seals have a spring that helps the seal hold it's shape. It's easy to roll a seal and dislodge that spring. A saw will pass the initial p&v test but fail shortly after being run.
Alanmurphy6912
ArboristSite Operative
Yes I have vac and pressure tested it multiple times now and I was also very careful installing the crank amd seals amd used a pop can to not roll the seal lip. I've been thru fuel and impulse lines and a tank that vented but leaked fuel to now a tank that let's air in ,no fuel out and no air out apparent out because when I crack the fuel cap at times it will hiss pressure out of the tank at the cap.
Alanmurphy6912
ArboristSite Operative
I'm not sure, I know they need to be vented as to let it get fuel by allowing air to take the place of the fuel its using. It depends who you ask,some say it on out needs to let air in the tank,and others say it needs to hold a certain pressure inside but be able to blow off the excess like on a hot day im not sure what to think. I'm sure I've got carburetor issues is probably part of it. I always tune it when its warmed up but i guess not whem its roaring hot from cutting so ill try again tomorrow and pay special attention to the exact settings of the carb and when it starts to fail. I know both jets affect each other but like the high jet I can turn all the way in and it'll still run and rev out. If I let the high jet out like 1 turn and the low out also 1 turn it will run when hot but won't rev high and bogs like.crazy so I let the low jet out slowly until it idlesand revs up nice without a hanging idle after letting off and it won't rev to more than 10k. It almost acts as if they are opposite of each other. I've tuned ever single saw I've ever owned and many customers saws amd don't usually have any issues. Thats why this one has me so boggled. I understand how both jets work and the typical starting settings etc. And everything I thought I knew about carbs ,this saw has defied. Lol
What about the boot or block that the carb mounts to? I have had a couple of Husqvarnas give similar issues as yours where it ended up being a cracked composite manifold or split rubber manifold boot. The issues were intermittent like yours and worsened once the saw was warmed up. Check your cylinder base bolts too.
I put a used oem carb on both of mine ,1 zama, 1 walbro.
I put a kit in them and didn't have 30$ in either. I also put the proprietary o-ring in behind the crank spacer on the pto side. Both saws run and idle as they should, now.
I put a kit in them and didn't have 30$ in either. I also put the proprietary o-ring in behind the crank spacer on the pto side. Both saws run and idle as they should, now.
Supervisor is correct. I put a used oem carb on my blue assembled 372, it already has an o-ring on the pto side. The 288 I bought doesn’t have any problems- yet.
Both carbs(china) ran the same?
No the 372 chink carb wouldn’t tune correctly, I put a good used oem carb on it and that fixed it. The carb on the 288 copy is fine - so far. Both of these saws have had the ass run off them the last 3 months and seem to be holding up. Oh yeah the 372 started leaking bar oil and I had to replace an o-ring on the pump
Pic #3 where the hose goes in. Will it pull out so you can put in a regular husky vent? Looks likely instead of a different tank. Might help the next fella with the same issue... and you may be able to sell/trade it verse watching dust collect on it....
I will be following/watching this thread. I bought a 365 with 372 p/c with bad crank bearings, I have a J2171 good crank and J2171carb for it. You guys are full of information that I really APPRECIATE. I will have near the 250$ or more in it so I understand the clone concept.. I only hope to avoid issues like what I am reading here SO A BIG THANKS FOR A GOOD READ.
TRTermite, I could be wrong, but I thought the vent is to equalize pressure in the tank... thus no pressure and no vacuum inside the tank.
The vent prevents raw fuel from leaking out and spilling all over the place, yet allows air in and out as needed. Am I right?
.
Yep Termite. The way I see it, the tank has to release pressure that builds up in the tank from fuel sloshing around. Also has to allow air into the tank as the diaphragm draws fuel and creates a suction.
He ought to try running the saw with no vent tube, duck bill, grub screw, of any kind... just an open hole. Simply run the saw, and hold the saw upright and don't do any dramatic cutting maneuver's. See how it behaves.
.
He ought to try running the saw with no vent tube, duck bill, grub screw, of any kind... just an open hole. Simply run the saw, and hold the saw upright and don't do any dramatic cutting maneuver's. See how it behaves.
.
YUP BUT that is where the needle valve pops off at 4, 5, 10, or even 15 lbs of pressure... The grub screw lets air in but liquid (gas) is thicker so doesn't really get out. (If it is shoved into tubing not screwed in). I believe the duck bill and others are a one way check valve. Give this thread and it will derail into a massive tank vent thread similar to the dreaded OIL THREADS.. Then we can sit back and interpolate an answer we can be comfortable with.
Alanmurphy6912
ArboristSite Operative
Yea I'd like to find an oem carb that I can buy or make trade for,.and yea I knew about the o ring behind the spacer before I built the saw s0 I bought one from husqvarna before I started the build as to not have leaks and so forth. Alot of people dont know about that o ring and it's super skinny like a rubber band
Alanmurphy6912
ArboristSite Operative
I have sorta tried pulling on that vent hose thinking the same thing before I bought the second tank, but your right now that i dont absolutely NEED that tank i could try it and if I screw it up in the name of science and helping others then so be it. Matthew Olsen on youtube I think does something with them tank vents but I'm not sure if it's the same style or not I dont think his video showed him removing it.
