372xp 50 pulls on cold start

[John Stryker]

Once started it will start again easily after a day of sitting, but after sitting for a week it takes at least 50 pulls or a shot of gas down the carb to start. Could this be the inlet needle not seating? Any suggestions appreciated. Thanks.

 

[cmhmhh]

If it starts with a shot of fuel through the carb the things to check would be:

Correct H/L screw settings
Diaphragms Faulty
Fuel Filter Clogged
Fuel Line Obstructed/Kinked
Impulse Line/Channel blocked or leaking
Blocked tank vent

 

[r black]

turn the ignition switch on before starting choke on pull till pops choke off ...no doubt a fuel line on filter issue

 

[Old2stroke]

Once started it will start again easily after a day of sitting, but after sitting for a week it takes at least 50 pulls or a shot of gas down the carb to start. Could this be the inlet needle not seating? Any suggestions appreciated. Thanks.

Not due to inlet valve not seating, could be the opposite, inlet valve sticking closed. Pulling the engine over has to develop enough vacuum to pull the main diaphragm down to open the inlet valve, pull fuel up the fuel line, through the check valves in the pump diaphragm, through the inlet valve and fill the fuel chamber. Fuel pump action from crankcase pulses has no affect at cranking speeds, it's all about the choke which must be COMPLETELY closed. A main diaphragm that is too stiff to be pulled down enough, and the check valve tabs on the pump diaphragm being stiff and sticky can be a problem. This is assuming your starting procedure is good, the throttle has to be set to the partially open (fast idle) position and stay there until the engine runs. A cold saw will seldom start with a closed throttle, so it you blip the throttle after it pops, the throttle will be returned to idle and must be reset to fast idle.

 

[John Stryker]

The hard starting only happens after sitting for a week. Otherwise it starts normally and the tuning is fine. I will probably inspect the carb and lines etc. I've just been too lazy to get at it before now.
Thanks guys for the input.

 

[Evan]

Fine tunning is subjective

 

[John Stryker]

Not due to inlet valve not seating, could be the opposite, inlet valve sticking closed. Pulling the engine over has to develop enough vacuum to pull the main diaphragm down to open the inlet valve, pull fuel up the fuel line, through the check valves in the pump diaphragm, through the inlet valve and fill the fuel chamber. Fuel pump action from crankcase pulses has no affect at cranking speeds, it's all about the choke which must be COMPLETELY closed. A main diaphragm that is too stiff to be pulled down enough, and the check valve tabs on the pump diaphragm being stiff and sticky can be a problem. This is assuming your starting procedure is good, the throttle has to be set to the partially open (fast idle) position and stay there until the engine runs. A cold saw will seldom start with a closed throttle, so it you blip the throttle after it pops, the throttle will be returned to idle and must be reset to fast idle.

Thanks, I will check those things.

 

[Old2stroke]

The hard starting only happens after sitting for a week.

After a week all the fuel has probably drained down out of the fuel line to the carb and just requires a lot of pulling just to get fuel up the line and into the carb. Does that saw have a really long fuel line?

 

[grizz55chev]

Check the comp!

 

[John Stryker]

After a week all the fuel has probably drained down out of the fuel line to the carb and just requires a lot of pulling just to get fuel up the line and into the carb. Does that saw have a really long fuel line?

That's what I figured too, and why I wondered if the inlet needle would let fuel drain back. It's just a normal length line. Filter is clean, compression is 150 psi, tank vent works, saw runs great ; I will just have to dig a little deeper into the carb, and double check the fuel line I think.
Thanks for your input, old feller.

 

[John Lyngdal]

I'd open up the low speed jet a 1/4 turn and see if that helps.
If not, open it up another 1/4 turn and try again.

 

[John Stryker]

I'd open up the low speed jet a 1/4 turn and see if that helps.
If not, open it up another 1/4 turn and try again.

Thanks for the suggestion; interesting, lots of things to try.
This saw runs very well once it starts, it's just taking it's time getting from the tank after a week of sitting. I have several of these saws, and other than this one, they all start within 4 to 7 pulls after sitting for a week. This particular saw will start with one pull after it's been run, and even a day or two later, but not after a week or more.
Like I said, I've been lazy; instead of tearing down the carb and replacing the fuel line etc., I just went and asked for ideas on here.

 

[CentaurG2]

Pull off the air cleaner and make sure the choke is closing completely. That saw was notorious for wear on the choke linkage. If the choke does not close completely, you will pull your arm off to try and get it to start cold.

 

[huskihl]

I would guess the diaphragms in the carburetor are a little bit stiff.

 

[John Stryker]

Pull off the air cleaner and make sure the choke is closing completely. That saw was notorious for wear on the choke linkage. If the choke does not close completely, you will pull your arm off to try and get it to start cold.

Thanks for the idea Centaur, I just checked and it does close totally. Also felt the fuel line which feels supple.

 

[John Stryker]

I would guess the diaphragms in the carburetor are a little bit stiff.

Thanks, yes, that's my next plan. I think I even have a carb kit here.

 

[CentaurG2]

Thanks for the idea Centaur, I just checked and it does close totally. Also felt the fuel line which feels supple.

Make sure to check it when it is in no start mode. It can be somewhat intermittent either due to operator error (glove hand not pulling choke completely out) or wear. I own 6 or 7 of those saws in one form or another and 2 of them had this issue. Great saw! Only other thing you need to worry about are the fasteners. Loctite is your friend. Oh, and as a last resort, you can also solder up the holes in the butterfly valve to give it a little more woof. Did that on my 371 and it did seem to help.

 

[Old2stroke]

you can also solder up the holes in the butterfly valve to give it a little more woof.

I have done that with a number of saws and trimmers. Makes a lot of difference.

 

[John Stryker]

Update! Problem solved!
I finally got off my lazy arse, and pulled the fuel line at the carb, and sucked on it with the Mityvac, and saw air bubbles, so then switched it to pressure, and saw air squirting out of the line about a half inch from the carb end of the line. So for now, I just nipped off that bad end and she started up in five pulls from cold after sitting for a week.
Sorry all for wasting your time with my questions. When you want something done right; just go ahead and do it, simple, haha. Actually, I probably will change the fuel line too although it seems nice and supple.
Thanks to all who answered.

 

[BrettS]

What I do on my 372 is stop switch off, choke in and give it two pulls, stop switch on, pull choke out and saw usually starts on two-three pulls.