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Backfire through the carb.

Tiny
ACURALEGEND187
  • MEMBER
  • 1989 CHEVROLET ASTRO
Bout a week ago my wife got in her van started right up get it warm up a bit and off she left for work she drove bout a good mile to a mile and a half nd POP POP POP throught the carb and when u push the gas u get the popping nd at idle u get the popping but when u drive it nd u take your foot off the gas and let it cruise nothing but at a stop light it wants to turn off nd back firing I changed the spark plugs/wires I fixed a leaking injector the only thing I did 2 days before this happened was I changed the sock in the tank nd it ran fine then it happened I hope its not the cam lob but some say that or the rotor nd distributor but I dont know I need this car fix asap it r only car nd it started to get cold down here so need to take the kids to school thank u and have a good day
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Friday, May 3rd, 2013 AT 6:01 AM

8 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check fuel pressure first if tbi it shold be 9-11 psi then check dist cap and rotor. Finally try pulling plug wires one at a time to see if stops popping. Then pull the valve cover to see if rocker is goin gup and down or a bent pushrod etc
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Friday, May 3rd, 2013 AT 6:21 AM
Tiny
ACURALEGEND187
  • MEMBER
  • 23 POSTS
Well I pulled the dist all the way out nd wen I turned it sideways the piece under the rotor was in lik 4 pieces so now I have to but another dist nd the fuel press I bought the kit fo that nd replaced it I dont have a press gauge to check the psi on it but some were sayin the lob on the cam was messed up or the timing chain was also messed up
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Saturday, May 4th, 2013 AT 8:46 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If the pieces found in dist that may be the reason. However just put the dist back in and see if rotor turns you don't need to hook It up. If it turns ok then rule out a timing chain if it kind of skips around thenthe tchain may be bad. Then either fix the dist or get another re time it when installing and it should be good to go.
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Saturday, May 4th, 2013 AT 8:49 AM
Tiny
ACURALEGEND187
  • MEMBER
  • 23 POSTS
Can u tell me the gap between rocker arm nd spring on my v6 4.3L chevy
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Tuesday, May 7th, 2013 AT 10:38 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It' 0 lash, I fyou have a gap then the cam is worn o r lifter out of adjustment. If it has never been adjusted then check for abent pushrod or worn camshaft.
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Wednesday, May 8th, 2013 AT 7:12 AM
Tiny
ACURALEGEND187
  • MEMBER
  • 23 POSTS
Well I took it apart lastnight nd I had a couple of bent rods everythin else looked ok but I got new rods nd cleaned up the heads is there anythin else I should look at before I replace the bent rods?
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Wednesday, May 8th, 2013 AT 6:10 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Hopefuly replacing the pushrods will cure it by why did they bend in the first place? Hard telling just make sure when youstart it to take it a little easy on the engine so to make sure things are ok. I wouldn't put he covers back on right away until it runs about a minute aor so and you are satisfied. To adjust the rocker arms take to 0 lash then 3/4-1 turn down on nut.0 lash is when lifters are all the way down on cam on both inlet and exaust.
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Thursday, May 9th, 2013 AT 6:04 AM
Tiny
ACURALEGEND187
  • MEMBER
  • 23 POSTS
Ok will do nd thank very much fo the help I mean it
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Thursday, May 9th, 2013 AT 10:05 AM

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