Don't know what to do

Hey everyone Im new to the forum and need some help. I have a 97 Jimmy that 's costing me a furtune. It had almost 174000 miles when it I first bought it. Now has almost 200000 and when it runs, it runs perfect. About 19 mpg to 22 on the hyw when I drive it. My wife can get about average 18. When I bought last year it had been sitting for about 8 months nobody could figure it out what was wrong and the gave up on it. I check Af and determined it needed a fuel pump so I bought it replaced it and all was ok execpt for the occasional stalling from time to time. Again after replaing a coil checked af and found the ignition switchs were common problems with GMC in 97 and I had all the systoms, dash lights cut out,stalling for no reason when ever no codes jiggle the key and alls well. Took it to the mechanic becuase I am always working and did'nt have the SPECIAL socets needed to replace it . Picked it up 2 days ago my wife has been driving it and said it's been good. Untill about 2 hours ago when she said it was sputtering and lacked power. She managed to get home in what I thought was a limp mode. when I checked it with my actron MAF came up. I erased the code drove it myself and it won't excellerate properly but idles great. What can it be? does it sound like MAF Im out of money and can't afford to guess or go back to the mechanic. Your help is appriciated. Oh yeah I cant type or spell worth a hoot .

Hey everyone Im new to the forum and need some help. I have a 97 Jimmy that 's costing me a furtune. It had almost 174000 miles when it I first bought it. Now has almost 200000 and when it runs, it runs perfect. About 19 mpg to 22 on the hyw when I drive it. My wife can get about average 18. When I bought last year it had been sitting for about 8 months nobody could figure it out what was wrong and the gave up on it. I check Af and determined it needed a fuel pump so I bought it replaced it and all was ok execpt for the occasional stalling from time to time. Again after replaing a coil checked af and found the ignition switchs were common problems with GMC in 97 and I had all the systoms, dash lights cut out,stalling for no reason when ever no codes jiggle the key and alls well. Took it to the mechanic becuase I am always working and did'nt have the SPECIAL socets needed to replace it . Picked it up 2 days ago my wife has been driving it and said it's been good. Untill about 2 hours ago when she said it was sputtering and lacked power. She managed to get home in what I thought was a limp mode. when I checked it with my actron MAF came up. I erased the code drove it myself and it won't excellerate properly but idles great. What can it be? does it sound like MAF Im out of money and can't afford to guess or go back to the mechanic. Your help is appriciated. Oh yeah I cant type or spell worth a hoot .

Welcome to AF.
There are spell checkers that you can down load.
One upper right labeled ABC check mark under it.

On your problem 97 is a bad year on ign switches.
Is dash light still acting up and does wiggle switch/key still help?
Has fuel pressure been rechecked after fuel pump replaced.
What brand of fuel pump was used?
Lot of fails on Airtex pumps.

What was the code no that came up?
ANY OTHER CODES?

Was code cleared and recheck after driving and acting up.

When it acts up is it losing fuel pressure or spark or power from ign switch?
What all did the mechanic do to it or say what the problem was?

IF YOU HAD IT TO A MECHANIC I WOULD TAKE IT BACK FOR HIM TO RECHECK ON HIS DIME.

Hi MT-2500 thanks for your help. Im still trying to navigate my way around this forum. this is the 1st time I have ever asked for advice on anything on the web.+ Ive got to get this truck on the road this weekend and would like to avoid going back to mech. He had it last time for over a wk. I would have order the E-4 torx socket on the web and replaced the ign myself if I had known. Oh one more thing Im 20 miles from the nearest city and its small town USA. Checked all around and could'nt find the tool needed.I dropped it of and 252.00 later Im looking at a new set of problems. Ok the ign SEEMs to be working properly,dash lights, stalling and all the other thing it was doing not giving me problem. Replaced fuel pump with a Bosch in july of last year, avoided the the one you mentioned because so many people said the same. Maf came up when I cheked codes yesterday. I just replaced it and theres no change. Taking the 20mile trip (one way) to get my money back. Maybe the SES will come on and Ill pay closer attn to the codes. I dont have a fuel pressure gauge Im going to borrow one at the store. My milage has dropped to 13 according the to digital display. Ill get back with you on the reading I think there supposed to be around 55 to 60 psi. Is that correct?

Hi MT-2500 thanks for your help. Im still trying to navigate my way around this forum. this is the 1st time I have ever asked for advice on anything on the web.+ Ive got to get this truck on the road this weekend and would like to avoid going back to mech. He had it last time for over a wk. I would have order the E-4 torx socket on the web and replaced the ign myself if I had known. Oh one more thing Im 20 miles from the nearest city and its small town USA. Checked all around and could'nt find the tool needed.I dropped it of and 252.00 later Im looking at a new set of problems. Ok the ign SEEMs to be working properly,dash lights, stalling and all the other thing it was doing not giving me problem. Replaced fuel pump with a Bosch in july of last year, avoided the the one you mentioned because so many people said the same. Maf came up when I cheked codes yesterday. I just replaced it and theres no change. Taking the 20mile trip (one way) to get my money back. Maybe the SES will come on and Ill pay closer attn to the codes. I dont have a fuel pressure gauge Im going to borrow one at the store. My milage has dropped to 13 according the to digital display. Ill get back with you on the reading I think there supposed to be around 55 to 60 psi. Is that correct?

On the Maf sensor code there is about 5 different codes.
Which point to which MAF problem you might have.
We need the code no. to help you on that end.
Some times when it is acting up you can disconnect the sensor and see if it changes the way it is running.

You are welcome.
The Delphi / AC delco pump are the best one.
Fuel pressure specs on 97 4.3 V6 is 60/66 lbs.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

Well I attempted to drive to the parts store an the SES light came back on. Checked the code and P0101 came up. Thats all. Howerver I did notice the temp guage is fluxuating around 160. When I checked it with my scanner temp reads 199 while driving. temp gauge has never been a problem. Untill the ign switch was replaced. Could it have something to do with it? Maybe a defective switch? Ill have to hunt down a fuel pressure gauge around this community to run the test as you recommended.

Well I attempted to drive to the parts store an the SES light came back on. Checked the code and P0101 came up. Thats all. Howerver I did notice the temp guage is fluxuating around 160. When I checked it with my scanner temp reads 199 while driving. temp gauge has never been a problem. Untill the ign switch was replaced. Could it have something to do with it? Maybe a defective switch? Ill have to hunt down a fuel pressure gauge around this community to run the test as you recommended.

Code 101 is MAF performance into VCM/PCM is not as expected.

Any air intake leaks into engine?
Any bad wiring or plug in's?

Even plugged exhaust system or engine running problems could be bad.
Even a bad new sensor.