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Oscar19
12-30-2018, 16:38
Hello guys,
I recently purchased a 1997 GMC Suburban 2500 6.5 Turbo Diesel 4x4. Now I’m having transmission problems with the truck, seems to have a delayed and hard shift from 1st to 2nd and 3rd and won’t go into 4th od, tops at 40 mph. Any clues on what might be causing this and what to check first before trying to do a full rebuild. Hope to hear back from y’all, thanks! Truck has 86K miles
snarl
12-30-2018, 17:13
How is the fluid level? Does the fluid smell burned?
Oscar19
12-30-2018, 21:04
No, fluid looks good doesn’t smell burned. But I’ll start there new fluid and maybe replace the filter.
DmaxMaverick
12-30-2018, 21:22
Welcome aboard!

Step one: Replace the fuel filter.

Then, verify the lift pump is running when it should, and is providing enough fuel pressure and volume. At idle, open the fuel water drain (Tee valve at the thermostat housing, routed to an appropriate container). The engine should continue to run while fuel fills the container.

Is the SES lamp on?
snarl
12-31-2018, 06:39
Check the temperature sender on the drivers side head is plugged in.
Robyn
12-31-2018, 07:07
I agree with Maverick

If there is an SES showing (Check engine lamp) pull the codes and see wasssssup..

If no codes, then definitely replace the fuel filter and follow what Maverick said...

A plugged fuel filter or failed lift pump can cause poor fuel flow and result in the low power.

With the engine not producing power as it should you are mashing on the throttle harder and this tells the computer that the throttle pressure is high and this results in the hard shifts.

The temp sender on the drivers side head is for the gauge only.. The sender on the water crossover up on the front of the engine is the temp sender to the computer...

Keep us in the loop.
Yukon6.2
12-31-2018, 10:19
Check your throttle position sensor.
A friends sons 97 gasser was having tranny issues.He was going to replace but did some more digging online and discovered the issue.
Replace the sensor and he is ratting the chyt out of it again.Been going for over a month now.
DmaxMaverick
12-31-2018, 10:23
Check your throttle position sensor.
A friends sons 97 gasser was having tranny issues.He was going to replace but did some more digging online and discovered the issue.
Replace the sensor and he is ratting the chyt out of it again.Been going for over a month now.

It's a 1997 6.5 EFI Diesel. No TPS.