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About 427dogs

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  • Other Trucks
    78 r model 300,92 rd 427,95 rd 427,97 ch 427, 05 granite 460, 82 kenworth 8v92 detroit, 88 6v92 western star, gmc inline, 77 international paystar
  1. i have been trouble shooting for over a month now. every time i flick the toggle switch for my marker lights, it pops the breaker, so i have installed a new switch, unplugged all connections at the firewall(eliminating any troubles outside the cab) and have inspected any wires i could under the dash. but when i wiggle the main harness under the dash the lights come on and stay on for maybe a day or until i hit the right bump. i believe the trouble is between the switch and the breaker panel but i really dont want to cut into the harness to unleash more mess.just wondering if anyone has ideas or has seen common trouble spots for these harness. p.s. when i get the lights on from wiggling the harness i cannout get them to go back out by wiggling it again.??????? and for some reason my fog light switch turns the marker lights on as well as the 2 way headlight switch. any sugestions would be greatly appreciated ...427 dogs...
  2. 1992 427 r model mack, you can be driving along at any speed and it will quit, the wipers will come on. it especially does when its raining or you hit a water hole. if you turn the key off and back on again quick the truck takes off like nothing happened. but it did it to me on a hill fully loaded and it kept doing it. i cleaned all the grounds up, checked for bare wires , any help will be greatly appreciated. maybe computer prob,relay i dont know. thanks
  3. well finally the problem was fixed, after 3 weeks with a truck that was unusable. you were right, the connection at the torque limit switch was bad, we would have never thought to look there nor did the mechanics. they forgot all about it. and the new wiring harness was loose at all connections on the firwall, but the connection at the torque limit switch was the problem. i thank you so much, you have saved us alot more time and money, should have asked 3 weeks ago i guess. anyway untill next time. thank you again. fixed 427
  4. we took our 1995 r model mack and swapped out the 400 motor and droped in a used 427, about three years ago. after some computer issues we finnally got the truck on the road, the 427 was incredably strong, right up till 3 weeks ago. the motor started to hitch and hesitate on hills, so we took it to a mack shop, the mechanic changed the injection pump with a good working used one and sent us on our way. the truck didnt hesitate any more, but lacked power, so he told us to take the original pump to get calibrated. we had the original looked at and calibrated, but there was nothing wrong with the pump, it was working fine, besides a little timing and cleaning. so we put it back on the truck, still lacking power. so they said it wasnt the pump it was the wiring harness to the pump, they changed it with a new one and gave us the truck back. we took the truck on the road with a EMPTY log trailer behind and it didnt just lack power now it could barely haul itself. we had to drop the trailer and take the truck to another mack shop. that shop said our turbo was cracked, so we put a good working used one on and still nothing, changed the air filter and fuel filters and all of the fuel lines, still nothing. new air to air, 6 new injectors, new intake sensors, boost gauge, STILL NO POWER. we can only get 15 to 20 psi boost from the turbo, 2 mechanics say the fuel pressure is fine 1 says it fluctuates. the temp gauge will read 180 after a quick run but the comp hooked up will read 108 and a temp gun shot at the manifold will read 103. first thing tommorrow morning i want to check all connections on the new wiring harness because after it was installed we lost all power. oh and the vavles have been set as well. if anyone has ideas or input please help. thanks frustrated 427. p.s. the turbo for the 427 is actually off of a 400 because the 427 turbo will not fit with the hood closed but the motor had tremendice power before with the other 400 turbo.
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