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I have a 1998 chevy 3500 pickup with a 6.5 turbo diesel. when cruesing or going down hill the rpm's drop and the truck starts to buck. It first started doing it at 85mph now its starts around 60mph. I have allready changed the pmd, fuel lift pump. please help.

Submitted: 99 days and 4 hours ago.

Category: Chevy

Value: $13

Status: AWAITING CUSTOMER ACTION

Year: 1998
Make: Chevrolet
Model: 3500 pickup
Engine: 6.5 turbo diesel

Already Tried:
replaceed fuel lift pump. pmd, fuel filter bleed whole system.

Posted by GNwrench 98 days and 20 hours ago.

Info Request

is the check engine light on?or will it come on when this happens?will it stall?or even crank and not start?

98 days and 20 hours ago.

Reply

no thats whats funny no service light no extra smoke starts right up even in dead of winter. never ever stalled when under a load it runs fine. thanks. I all so have a code reader, no codes!

Posted by GNwrench 98 days and 20 hours ago.

Info Request

ok good..well hmmmmmmm..im wondering when its bucking if it is the engine or the trans toque convertor lock up your feeling...can you duplicate it if you want to very easy on a roadtest?

98 days and 19 hours ago.

Reply

Yes just take it up to 60mph on a flat road or down hill. Once you take the load off the engine at that speed it drops rmps then when you step on the pedal it bucks an the bangs in to gear. Thanks

Posted by GNwrench 98 days and 19 hours ago.

Info Request

ok well what we can have you do to see if its the torque convertor lockup is drive it and get it to ride the brake pedal just enough not to apply the brakes but enough to turn on the brake lights..when the brake lights go on the brake switch also tells the computer to unlock the convertor...and see if that maks any differnce..did you under stand what we are trying to acomplish?

98 days and 19 hours ago.

Reply

Yes! will do this to day.

Posted by GNwrench 98 days and 19 hours ago.

Info Request

ok let me know

94 days and 2 hours ago.

Reply

Relist: I still need help.

Posted by GNwrench 93 days and 23 hours ago.

Info Request

ok do you have any access to a scan tool where we can view the data in the computer?we are looking to view the injection closure time on the data list..can you find out what the closure time is?

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Question

I have a 1998 chevy 3500 pickup with a 6.5 turbo diesel. when cruesing or going down hill the rpm's drop and the truck starts to buck. It first started doing it at 85mph now its starts around 60mph. I have allready changed the pmd, fuel lift pump. please help.

Optional Information

Year: 1998Make: ChevroletModel: 3500 pickupEngine: 6.5 turbo diesel Already Tried: replaceed fuel lift pump. pmd, fuel filter bleed whole system.

Info Request

is the check engine light on?or will it come on when this happens?will it stall?or even crank and not start?

Reply

no thats whats funny no service light no extra smoke starts right up even in dead of winter. never ever stalled when under a load it runs fine. thanks. I all so have a code reader, no codes!

Info Request

ok good..well hmmmmmmm..im wondering when its bucking if it is the engine or the trans toque convertor lock up your feeling...can you duplicate it if you want to very easy on a roadtest?

Reply

Yes just take it up to 60mph on a flat road or down hill. Once you take the load off the engine at that speed it drops rmps then when you step on the pedal it bucks an the bangs in to gear. Thanks

Info Request

Reply

Yes! will do this to day.

Info Request

ok let me know

Reply

Relist: I still need help.

Info Request

ok do you have any access to a scan tool where we can view the data in the computer?we are looking to view the injection closure time on the data list..can you find out what the closure time is?

Related Chevy Questions

Year: 1998
Make: Chevrolet
Model: 3500 pickup
Engine: 6.5 turbo diesel

Already Tried:
replaceed fuel lift pump. pmd, fuel filter bleed whole system.