Apollo77 Posted June 20, 2009 Report Share Posted June 20, 2009 i have a 77 620. truck starts and can drive. but i keep backfiring in my carb. it seems to do ok when at a high rev but eventually will backfire and give out. i looked at some posts and will be checking the timing, but the posts i read they weren't getting it started while having this problem. please help? ... anyone? DV Quote Link to comment
yellowdatsun Posted June 20, 2009 Report Share Posted June 20, 2009 If it's backfiring through the carb, it's 99% always a timing problem. Just crank the dizzy a bit one way to see if it get's worse or better. Quote Link to comment
Apollo77 Posted June 20, 2009 Author Report Share Posted June 20, 2009 i seem to have gotten the backfiring to stop but i cant seem to get it to idle. only stays on if i have my foot on the pedel DV Quote Link to comment
polski ogorki Posted June 20, 2009 Report Share Posted June 20, 2009 thats always fun the brake throtle at the same time to keep it from staling at an intersection!there is an adjustment on yer carb linkage.the stuff yer cable moves around. just turn it clockweise a bit and buy this book! Quote Link to comment
Apollo77 Posted June 20, 2009 Author Report Share Posted June 20, 2009 any other ideas? ive turned what i can think is the idle screw to the point that it almost comes out. and the mixture screw is the only other one that i can see that i can ajust. and neither one seems to effect the idle, just how it runs when i can get it turned over thanks for the ideas so far btw and ill keep an eye out for that book DV Quote Link to comment
datzenmike Posted June 20, 2009 Report Share Posted June 20, 2009 The hex shaped thing with the red wire is the idle cut solenoid. If there isn't 12v on the red wire the solenoid remains closed and no gas gets to the idle circuit. No gas... no idle. Check that it is working by turning the ign. switch to on (don't start) then off, on, off, on, off. Listen at the back of the carb, you should hear a clicking sound. If not find out if there is voltage with the key on. It should get it's power from the same circuit as the coil. Quote Link to comment
Apollo77 Posted June 20, 2009 Author Report Share Posted June 20, 2009 thanks for the pix, how can you tell if its bad? can it be bad? i can hear a clicking sound but im not sure if its coming from the dash or the carb. the shitty lil volt tester i have says 12v when i test it but it seems to have a bit of a hard time holding the current, it flashes 12v when i move the wire. ill try swaping with the other truck to see if there is a change in my situation. DV Quote Link to comment
datzenmike Posted June 20, 2009 Report Share Posted June 20, 2009 It should have a steady 12v with key on. You could remove the solenoid. (don't loose the spring) Use a can of WD-40 or carb cleaner. Use the straw that comes with it and spray directly into the hole to blow out any dirt. Quote Link to comment
Apollo77 Posted June 21, 2009 Author Report Share Posted June 21, 2009 well i put in a different solenoid, and this one makes noise when i unplug it so that part i know is in working order. however i cant seem to get it to idle. when i first pt the new one in it tried to idle but it didnt last long and ever since then its a no go. ive tried counting the turns on the what i think is the idle screw and the mixture screw and still come up with nothing. DV Quote Link to comment
datzenmike Posted June 22, 2009 Report Share Posted June 22, 2009 Mixture screw is the far right one, idle speed is just behind the accelerator pump rod. Both have a spring under them. Remove the mixture screw and insert the straw from a can of WD-40 or carb cleaner and spray it out. Lightly bottom the screw and then back out about 2 turns. You may also have a vacuum leak: check that the carb mounting bolts are tight. Check the intake mounting bolts are tight. Look for loose, missing or cracked hoses. Quote Link to comment
Apollo77 Posted December 22, 2009 Author Report Share Posted December 22, 2009 anyone know why i would have an idle that is way high? ive turned the mixture screw two out and played with the idle screw all over and still cant get it to kick down. if i had to guess id say its up around 5-7grand and it makes it really hard to drive around with your foot on clutch break and gas. any ideas?? DV Quote Link to comment
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