1999 Chevy Suburban Major vibration pulling hills

Sounds like a possible fuel pump issue. You need to hook up a fuel gauge to it and monitor the fuel pressure when the symptoms are present. I am expecting the pressure is out of spec.

Thanks for the suggestion. It sounded to me like a low pressure issue with the fuel pump.

What bothers me is that the fuel pump was replaced < 14,000 miles ago, and the fuel tank sending unit was replaced < 29,000 miles back. Is there something else causing the fuel pump to fail prematurely?

I'll check the fuel pressure before proceeding.

Thanks.

A plugged fuel filter can kill a pump. We ALWAYS replace the filter when a pump is done. I have seen many aftermarket pumps that are low quality.

That's what I was afraid of. Unfortunately, the GM dealer was responsible for replacing the fuel pump WITHOUT replacing the fuel filter for the previous owner. At least the dealer said the pump was GM.

Thanks for the responses and suggestion. I'll let you know how it turns out.

Hi-

Here is an update on the suburban diagnosis. Fuel pump seems to be working properly, and they checked for misfires, etc. Diagnosis is replacement of the torque converter.

My big question of the day is will replacing the torque converter fix the problem, or is there an underlying problem causing the torque converter to intermittently malfunction? Any thoughts?

Thanks,

It may be. I would have them make sure that the software has the latest and greatest updates.
Just need to get what calibration it has.

Not sure if a valve body would cause a shudder, but can give a hard shift. Transgo makes kits for this.

Same shudder under load or after a continious highway speed 55-65. I am no professional but from what I researched and what others said one of the lifters may be sticking. It happened to me on a couple of occasions. I purchased a can of SEAFOAM. poured 2/3 of a pint in my crankcase and reserved a 1/3 for the intake. Get the car hot park it with engine running pull the vacuum line off the master cylinder power booster you may have to hold the accelerator down to keep it running. I used a hair dye bottle to measure the ounces around 5-6. Slowly squirt the seafoam into the vacuum line be careful the line has a very strong pull and will rip the bottle out of your hand if too close. shut car off and let sit for 5 minutes. Do it at night because after restart get out of your neighborhood it SMOKES!!!!! You won't be able to see behind you run the car till smoking stops take it on the highway it dissiaptes pretty quick. Problem solved same EXACT issues you are having are gone. Change oil after a couple of days. You can also add some to gas read the bottle. Hope it helps and saved you some $. 99 sub 115,000 miles original owner, new AC fuel pump installed few months ago in addition to fuel filter

This is the second time I am doing this, the first time I went for about 8 months before re-occurence. In addition to the problem going away there is a noticible performance increase faster pedel response smoother idle,etc.,

Hi and thanks for the detailed reply. Obviously I forgot to check for new responses!

I took the car to a local trans shop, and the owner was quite helpful in trying to pinpoint the source of the problem. Since it didn't shudder for him, he was hesitant to change parts based on just a guess -- refreshing.

I'll call him tomorrow and mention your theory about the lifter. It sounds plausible, given my other symptoms.

Thanks again, and I'll let you know how it turns out.