Author Topic: Walbro HD 34A accelerator pump  (Read 573 times)

0 Members and 44 Guests are viewing this topic.

Offline kr5258

  • 4 cube
  • **
  • Posts: 33
  • Karma: 2

  • Total Badges: 16
    Badges: (View All)
    Level 4 Mobile User Fourth year Anniversary Third year Anniversary 10 Posts Level 3
Walbro HD 34A accelerator pump
« on: January 11, 2016, 08:47:02 pm »
Having a tuning problem with a MS361. Carb tunes normally on the low side but I can't get enough fuel into it on the high side. The saw runs up close to 15k no matter how many turns out on the H screw. Carb swapped from another MS361 and saw tunes normally.
The problem carb has been kitted and thoroughly gone thru. I suspect the accelerator pump circuit is pulling air in past the pump piston. Pump piston shows scoring just as I have seen on the problematic MS200t ZAMA C1Q-S126 accelerator pump.
Can anyone verify this theory before I plug the pump bore to test (and give myself another project trying to get the plug out)?

Share on Facebook Share on Twitter


Offline jmester

  • Global Moderator
  • Nitro Hotsaw
  • *******
  • Posts: 2106
  • Karma: 171
  • Location: MD

  • Total Badges: 36
    Badges: (View All)
    Tenth year Anniversary Nineth year Anniversary Eighth year Anniversary Seventh year Anniversary Sixth year Anniversary Level 6
Re: Walbro HD 34A accelerator pump
« Reply #1 on: January 11, 2016, 10:17:47 pm »
From what I understand if the pump piston is scored it will not hold a vacuum behind the pump piston to draw fuel from the metering side of the carb. I am not sure if it feeds fuel the hole time the throttle is open or just when you first depress the throttle.
FEAR NO TREE. FEAR GOD.

 

Related Topics

  Subject / Started by Replies Last post
2 Replies
1814 Views
Last post July 15, 2012, 07:13:26 am
by farmboy
7 Replies
1174 Views
Last post October 15, 2013, 08:14:57 pm
by jmester
7 Replies
669 Views
Last post November 22, 2013, 02:02:14 pm
by Cut4fun .
394 oil pump ?

Started by alsled « 1 2 » Husqvarna

15 Replies
1015 Views
Last post November 23, 2013, 07:43:04 pm
by alsled
5 Replies
1127 Views
Last post January 25, 2014, 03:07:17 pm
by Infinitive
1 Replies
234 Views
Last post February 25, 2014, 01:13:52 pm
by DCC
6 Replies
1012 Views
Last post February 04, 2017, 10:22:40 am
by mowertech
3 Replies
744 Views
Last post November 18, 2014, 09:54:51 pm
by Eccentric
2 Replies
679 Views
Last post January 28, 2018, 03:30:51 pm
by 3000 FPS
0 Replies
296 Views
Last post July 20, 2022, 09:42:16 am
by Cut4fun .