73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: Stewart G Griffin on January 16, 2008, 08:04:09 pm
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So anyways, i'm finally getting it re-activated (long story why it took this long).
Two issues i'm having are:
1) The throttle gets "sticky" alot; i can put my foot under the gas pedal and lift up and that brings the rpm's back down, so it's not too serious. But it shouldn't be like that.
2) It "diesels on' sometimes after i shut it off, which probably has something to do with the idle-stop solenoid thing (fig.A) which i'm not sure how to adjust.
(http://i223.photobucket.com/albums/dd31/sencraig/1.jpg)
i've made a close-up, so as to better asertain if i've hooked up something improperly:
(http://i223.photobucket.com/albums/dd31/sencraig/2.jpg)
Lastly, i wonder if the routing of the throttle cable is ok? i've traced it's route in yellow.
(http://i223.photobucket.com/albums/dd31/sencraig/4.jpg)
NOTE(S):
i'm using the edelbrock "pro-flo" air cleaner only because i feel that it is easier to tune (and see) everything right now. After everything is in order, i will probably revert to the stock air cleaner housing. i got the proflow off of another car that i bought and have since sold.
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You could spray your carb down with WD-40 to free up the stickyness. Your cable looks fine. Now after lubing up your carb doesn't work than your cable is sticking and need to chage it out.
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I would rebuild it...And clean it vary well...And get all the carbon build up off them throttle plates...If you dont want to rebuild it i would still clean the carbon off the throttle plates
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Maybe your return spring is weak? How is the accelerator pedal? Hard to push down or real soft? Have to remember, ours aren't like the new stuff where it's all computer controlled. Run on can be caused by the choke still being engaged.
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The choke works ok; i've verified this visually---it opens up fully after about 1 1/2 minutes.
The pedal feels ok, i suppose---not too hard or soft i guess. But do throttle springs weaken over time? i'm thinking it might be the springs because while moving the throttle by hand, i noticed that it returns back to idle slowly---it doesn't snap back like it probably should. Also, if you look at my pictures, there is a gap in the springs near where they connect to the throttle arm. Is this normal?
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Also, if you look at my pictures, there is a gap in the springs near where they connect to the throttle arm. Is this normal?
No, that is not normal. The springs have been stretched too far sometime during thier life. Try replacing them, while they're off check throttle plate action, if stiff rebuild the carb. The dieseling is most likely your timing too far advanced.
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Also, if you look at my pictures, there is a gap in the springs near where they connect to the throttle arm. Is this normal?
No, that is not normal. The springs have been stretched too far sometime during thier life. Try replacing them, while they're off check throttle plate action, if stiff rebuild the carb. The dieseling is most likely your timing too far advanced.
I'd fix one at a time. It's possible that the dieseling is caused by the idle being too high because it's not coming back to the actual idle by the screw.
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Adjust your timing to get rid of the dieseling.
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Dieseling can be caused by several factors:
Idle speed too high
Vacuum leaks
Carbon deposits
hot spots
Wrong spark plug heat range
EGR
lean a/f ratio
incorrect ignition timing
overheating, wrong glycol mix
etc...
So find the root cause before you start messing with everything. As far as the throttle sticking, dow you feel the linkage bind as you open and close the throttle shaft by hand?
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Also, if you look at my pictures, there is a gap in the springs near where they connect to the throttle arm. Is this normal?
No, that is not normal. The springs have been stretched too far sometime during thier life. Try replacing them..............
That's what i was thinking. i'm ASSuming that these are the original springs (it's a 83 c-10). Do you know of any good sources for replacements? I.e., jegs/summit etc?
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I think the purpose of that solenoid is to bump the idle up a bit when the AC is on. My 305 used to diesel too, it turned out to be the choke. A quick easy fix in my case.
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Also, if you look at my pictures, there is a gap in the springs near where they connect to the throttle arm. Is this normal?
No, that is not normal. The springs have been stretched too far sometime during thier life. Try replacing them..............
That's what i was thinking. i'm ASSuming that these are the original springs (it's a 83 c-10). Do you know of any good sources for replacements? I.e., jegs/summit etc?
Any decent parts shops should have return springs. Should be a universal item. You may have to cut them to fit though.
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Dieseling can be caused by several factors:
Idle speed too high
Vacuum leaks
Carbon deposits
hot spots
Wrong spark plug heat range
EGR
lean a/f ratio
incorrect ignition timing
overheating, wrong glycol mix
etc...
So find the root cause before you start messing with everything. As far as the throttle sticking, dow you feel the linkage bind as you open and close the throttle shaft by hand?
i don't really feel any binding. When i release it from higher rpms, it will come back down to idle real slow sort of like pouring syrup on pancakes.
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About the dieseling:
Is this harmful to the engine?
As far as i remember, i've got the timing set at 8 deg.
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1) OK, i've pretty much solved the dieseling problem; It turns out that the idle speed was too high.
2)And, i actually touched the throttle return springs--- and they have no tension! So, i've ordered the stock springs from a chevy dealer. i was going to get the return springs thru jeg's or summit, but the problems is that jeg's and summit now charge a $10 or $11 handling fee with each order (when did this happen?) And so, the handling fee would have been higher than the springs themselves----i was going to get the Gardner-wescott springs from summit for $7.95, but then the total would have been $18.90.
Someone suggested that i try a chevy dealer and they were $2.95.
i will update on progress.
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UPDATE:
i installed the $2.95 stock chevy springs i got at a chevy dealer and they work great. There is no "sticky" throttle.
But, there turns out to be another problem; See post entitled "QUADRAJET 102."