fulton fire Posted June 4, 2010 Share Posted June 4, 2010 i am having a problem with my 45 model 45 when i hit the highway all is well until i go about 40 mph then all of a sudden it dies and the choke knob pulls out by itself. i have replaced all the fuel lines ,installed a new fuel pump, i even took off the fill tube cap thinking it was pulling a vacum in the tank due to poor ventalation. i was wondering if anybody has ran into this problem. i will be driving this truck to a state fire convention in 2 weeks where it will be used for the pumper races so any input will be great because i would like to drive it there instead of trailering it. thank you for and help. Quote Link to comment https://www.bigmacktrucks.com/topic/14200-carb-problem/ Share on other sites More sharing options...
bullhusk Posted June 4, 2010 Share Posted June 4, 2010 Fulton, I know this is gona sound stupid but did you try wireing the choke open? Maybe the choke cable or the lingage is worn so as when the truck is running the choke starts to close an when it gets about half way the vacuume pulls it shut. Just a shot in the dark but i had an old Plymouth slant 6 that used to do just that! Quote Link to comment https://www.bigmacktrucks.com/topic/14200-carb-problem/#findComment-56510 Share on other sites More sharing options...
Freightrain Posted June 4, 2010 Share Posted June 4, 2010 I'm kinda thinking the same thing. Guessing it's an updraft carb too? Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/14200-carb-problem/#findComment-56521 Share on other sites More sharing options...
Mike Posted June 4, 2010 Share Posted June 4, 2010 They say great minds think alike. The butterfly valve on top of the carb. is closing making it shut down and starve for fuel. Yes i'd replace the choke cable from what you have described. While it is running or idleing while at raod temp. the butterfly valve should be wide open ( straight up and down position ). mike Quote Link to comment https://www.bigmacktrucks.com/topic/14200-carb-problem/#findComment-56522 Share on other sites More sharing options...
randyp Posted June 4, 2010 Share Posted June 4, 2010 They say great minds think alike. The butterfly valve on top of the carb. is closing making it shut down and starve for fuel. Yes i'd replace the choke cable from what you have described. While it is running or idleing while at raod temp. the butterfly valve should be wide open ( straight up and down position ). mikeoh yeah,,,you guys are good,,i think you nailed it,,randy Quote Link to comment https://www.bigmacktrucks.com/topic/14200-carb-problem/#findComment-56523 Share on other sites More sharing options...
fulton fire Posted June 5, 2010 Author Share Posted June 5, 2010 i took a closer look at the carb and the butterfly is only open about1/2 way even when gas is wide open so im going to take off the carb and fix it . ty for the input Quote Link to comment https://www.bigmacktrucks.com/topic/14200-carb-problem/#findComment-56559 Share on other sites More sharing options...
Mike Posted June 6, 2010 Share Posted June 6, 2010 oh yeah,,,you guys are good,,i think you nailed it,,randy Your right Randy......we need a few more responses....some concrete help, that ought to help him. Can't figr why Rob didn't help out. I guess he was getting some babying on his tooth situation. Can't figr why Rob didn't let me pull that tooth with my B model. He could have sat down on the ground and held onto the corner of the house. Or sat on his new YAMI HAW and held the brakes. mike Quote Link to comment https://www.bigmacktrucks.com/topic/14200-carb-problem/#findComment-56660 Share on other sites More sharing options...
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