Author Topic: Ok so I have a new theory on why my car is backfiring hesitating  (Read 2878 times)

Offline torqueaddict

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Ok so I have a new theory on why my car is backfiring hesitating
« on: October 27, 2011 - 11:59:45 PM »
Ok so I think I know why my car is driving like crap, it hesitates backfires and just doesnt drive like its supposed to. The new theory is my fuel lines are hose which are insufficient according to my mechanic. They were ran poorly have kinks all throughout the lines and he thinks that my car is being starved for gas at higher rpm's. It drives well from first and has lots of power, however at higher rpm's while in motion it does not behave like a mopar. Since adding the stealth heads I notice the added power and am pleased with that but I have to get this issue handled. I was so frustrated I wanted to scrap the motor, take the heads and build my 440. Does this isound like it could be the cause? He insists my bottom end is really strong and my top half is now solid, it sounds logical I am just a noob and tired of spending money haphazardly.
1972 Challenger  (O O [======R/T=] O O) 1970 clone




Offline guvnuh

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #1 on: October 28, 2011 - 02:57:16 AM »
You may want to check your spark plugs to see if you're running lean (white) or rich (black and dry).  Both could be the problem if it's backfiring and hesitating.  If your mixture is right, they should look tan.  I always recommend metal lines for fuel, but I think they should be OK regardless of the material, though I would definitely remove any obvious kinks.  Have you had any timing issues?  Just a couple places to look before you spend a bunch of money or scrap the motor.

-J
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Offline torqueaddict

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #2 on: October 28, 2011 - 03:15:34 AM »
You may want to check your spark plugs to see if you're running lean (white) or rich (black and dry).  Both could be the problem if it's backfiring and hesitating.  If your mixture is right, they should look tan.  I always recommend metal lines for fuel, but I think they should be OK regardless of the material, though I would definitely remove any obvious kinks.  Have you had any timing issues?  Just a couple places to look before you spend a bunch of money or scrap the motor.

-J


My timing has been adjusted alot, it still backfires. And I have replaced plug and wires numerous times. This is rather frustrating might I say again.  I guess the fuel lines are the only thing that hasnt been tampered with in that regard, the carb and everything else has been played with too. I wonder if anyone has a similar horror story and possible resolution.
1972 Challenger  (O O [======R/T=] O O) 1970 clone

Offline ireland383

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #3 on: October 28, 2011 - 06:53:17 AM »

My timing has been adjusted alot, it still backfires. And I have replaced plug and wires numerous times. This is rather frustrating might I say again.  I guess the fuel lines are the only thing that hasnt been tampered with in that regard, the carb and everything else has been played with too. I wonder if anyone has a similar horror story and possible resolution.
You say you keep changing plugs.  What did they look like?  When I first had my heads put on it was sucking oil, bad intake seal.  Similar symptoms to yours.  Plugs kept getting oil fouled.  Resealed the intake with the paper gaskets and voila.  As far as gas starvation, are you running a pressure gauge?
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Offline Chryco Psycho

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #4 on: October 28, 2011 - 12:40:45 PM »
run a compression test .
 Is it backfiring into the exhaust or carb , if it is in the carb that is usually lean condition , however if it instantly backfires the carb should still be full .  You can disconnect the fuel line & see how much fuel gets pumped up out of the line at the carb , you should get a cup in 15 seconds or so . Suction is very inefficient so if the fuel lines are kinked it could easily be starving for fuel . What size tube are you using ?
Timing should be 14-16* at idle & 36*@ 3000.
 are the ign wires tied together or seperated ? If the wires are in poor condition it is easy to have the spark jump wires if they are tied together . Any moisture under the dist cap ? Are you running Electronic ign ? If so check the gap between the reluctor & pickup , it should be .008 , I have seen engines run poorly just because the gap is too large.
 Do you have adjustable valves ? If so is one adjusted too tight ?

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Offline BadJoey

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #5 on: October 29, 2011 - 05:22:32 AM »
I'm wondering what you mean by kinked ? If it is a round bend no big deal . If the line is dented in reducing the inside diamiter I would fix that even if that is not the cause . :bigsmile:

Offline torqueaddict

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #6 on: October 30, 2011 - 01:27:28 AM »
You say you keep changing plugs.  What did they look like?  When I first had my heads put on it was sucking oil, bad intake seal.  Similar symptoms to yours.  Plugs kept getting oil fouled.  Resealed the intake with the paper gaskets and voila.  As far as gas starvation, are you running a pressure gauge?


No pressure gauge, that might be it but the heads have been removed previously for various reasons, (not by the same mechanic every time tho) so I doubt its the gasket. Im not really sure how the plugs looked.
1972 Challenger  (O O [======R/T=] O O) 1970 clone

Offline torqueaddict

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #7 on: October 30, 2011 - 01:36:24 AM »
run a compression test .
 Is it backfiring into the exhaust or carb , if it is in the carb that is usually lean condition , however if it instantly backfires the carb should still be full .  You can disconnect the fuel line & see how much fuel gets pumped up out of the line at the carb , you should get a cup in 15 seconds or so . Suction is very inefficient so if the fuel lines are kinked it could easily be starving for fuel . What size tube are you using ?
Timing should be 14-16* at idle & 36*@ 3000.
 are the ign wires tied together or seperated ? If the wires are in poor condition it is easy to have the spark jump wires if they are tied together . Any moisture under the dist cap ? Are you running Electronic ign ? If so check the gap between the reluctor & pickup , it should be .008 , I have seen engines run poorly just because the gap is too large.
 Do you have adjustable valves ? If so is one adjusted too tight ?

I think its backfiring into the exhaust. It pops alot when it gets to around 4k. I believe the lines are 3/8 robber hose, I am not sure about the wires to the box or the cap but I doubt the lines are tied together or there is water under the cap. I do think my ignition box may be bad however, and I have the electronic mopar distributer and box. Let me know if that helps at all.
1972 Challenger  (O O [======R/T=] O O) 1970 clone

Offline torqueaddict

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Re: Ok so I have a new theory on why my car is backfiring hesitating
« Reply #8 on: October 30, 2011 - 01:39:05 AM »
I'm wondering what you mean by kinked ? If it is a round bend no big deal . If the line is dented in reducing the inside diamiter I would fix that even if that is not the cause . :bigsmile:


Its rather hard to explain, they are bunched up to say the least. I would rather go with new aluminum lines anyway. Seems like less hassle later.
1972 Challenger  (O O [======R/T=] O O) 1970 clone