RonnieT

I unhooked the vacuum while I had the gouge on it and running and it went up a couple pounds, put it back on an it lowered it to what it normally runs. Mind now this doesn't stall every time, it just takes a spell when it does, usually after a trip up town and kill it and get back in to start and go on another errand and then it will happen, but not every start up only when it feels like it. if you soft peddle the accelerator it will usually come around in about a block of travel before the trans makes its first shift. after that is fine. the only think I am moving is a slight movement of the accelerator. back and forth. PSI on gauge never changes during this hesitation.

thank you ! Would either of these be the cause of any acceleration hesitation on take off from a standing stop and not every time, only occasional? (No codes on scanner)

No , nothing like that on the dash, I just wondered if it had anything to do with the towing button on the end of the gear shift lever? No numbers on the TPS just 3 wires and a round connection. I am having hesitation problems with taking off from a standing start. and it has something to do with the Throttle as I let off with my foot it picks up, if I put my foot down on the accelerator it is hesitant for sometimes almost 2 blocks of it before it runs correctly. Changed out 3 new fuel pumps and filters, I have had a Fuel pressure gauge on the windshield for 2 months so I can monitor it. It usually runs about 50PSI+ sometime 45PSI (with all 3 pumps, 2 new Delphi and one new Carter) it is NOT the Fuel Pressure because Its does it at 50psi and hardly ever at 45PSI. I am thinking it is the TPS or a bad ground? As my foot has to move very little to make it run better, nothing else moves just my toe pre se. No codes either.

2000 GMC 3 door 4X4 5.3 auto. Was thinking about changing the TPS and book wants to know if it has Traction Control? how do I know? the TPS has 3 wires in it and the connection is round if that helps any? Ron

I have a 2000 GMC 4x4 1500 3 door ,has 157,000 + miles, always taken care of and put on new parts when needed was wondering if anyone can tell me what these 3 items are and their functions on the 5.3L engine. These are one top the engine with cover removed, I know the TPS and the MAF sensors and the Pressure regulator but was wondering abut these , see the 2 pictures. One looks like a solenoid above the TPS and the one behind it to the left on the plenum? the 3rd one is under the firewall cowl at top rear of engine. Ron

OK Update on the blend door I installed yesterday, this morning when I started the vehicle, I heard a loud popping and grinding coming from the blend door actuator I installed yesterday, I quickly turned off the ignition and reached down and unplugged the wiring to the actuator , maybe I didn't kill it. Although after installing yesterday, I dove it several miles and I listed to it turning when I moved the dial each time and nothing unusual until this morning. When i installed it I turned the blend door with my fingers to the position that was on the actuator whish was straight across left to right. then bolted it up and installed the wire, turned the key on and the blower and moved the middle knob from cold to middle then to hot and back and it moved each time. So is the Mode door actuator that is not working now throwing a signal to the blend door?

A brief history first. I have owned this 2000 GMC 3 door 5.3Lt. for about 15 years now, when I got it , the heater never worked well, but I changed the cabin filters a few times, the heater core, the thermostat and coolant , water pumps, belts etc. It would never blow hot air on my feet. About 6 months ago during the start of the winter, I decided to change to mode door actuator , with a Dorman unit 604-113. The one that is above the drivers right leg. I had pure hell trying to twist my way in there and get it all aligned up to install. I did it several times but always failed with the correct way the dial on the dash said it should be blowing , but finally did get it installed. about a week later my "blend door " actuator quit working and stated popping sounds when going from cold to hot on the dial. that was OK because it was stuck on hot. Now that it is summer I bought a new Blend door actuator and installed it, no problem there. but I then noticed that the mode door was not working as every place on the dial only blows out the defroster vent. I pulled the panel off under the steering column and looked at the Mode actuator as I turned the dial and the gears or the "wheel" on the actuator is not moving at all. Checked the fuses and all are good. Did I do something wrong while installing the Blend door actuator? or did the Mode door just fail? The Dorman I bought had the "wheel" built on the actuator. Is there a video or something that would help me in getting the Mode door actuator off and back on correctly the first time? how to align the 2 doors on the wheel and the teeth on the other door. My heater control is the 3 knob type with no driver or passenger separations. Ron

Thanks carl for the reply, I cant believe that I got TWO Delhi units and both have issues. As soon as I get my money back from Rock Auto on the first unit, I am going to turn this one in to see If I can get credit on the 2nd one. Then I may buy a Carter or a cheap AirTex to see if they will pump at least 58 PSI and not rattle whine or knock. I went and dug mine original one out of the dumpster so at least If I want to I can get a new pump and fuel sensor for it and rebuild it. At least it didn't whine but would only pump at 45PSI. I don't think I can buy a stand alone pump or fuel sensor for the Delphi units or aftermarket units so that is why I am keeping the original unit and its wiring connector. I am glad that I decided to cut a door in the bed to change this pump instead of dropping the tank or taking off the bed, as it is , looks like I would need to hinge the door.! I guess China is screwing up all our import parts now. Ron

OK no one replied to the "Knocking Delphi fuel pump" so I guess I'm the only one that ever experienced this. The knocking or rattling pump did fix my low pressure stalling issue but I felt that in 30-90 days I would have a bad pump on my hands again so I filled out the warrenty on the Rock Auto website and bought another new Delphi FGO407 unit and paid them for it, so when it came in I could return the knocking unit for a refund on it. I did the warrenty work Saturday, got the new pump today and installed it, started the Pickup and it sounded good no knocking. Packaged up the other one along with papers for return papers and took it to the FedEx drop site. Now I'm back to stalling and lurching. When I returned home I put my fuel gauge on it and I have 46 psi with regulator hooked up and 52 psi with it unplugged. Is this for real? I never got a bad pump in my life and I have bought bottom of the barrel pumps in the past. I get 2 Delphi units and both have issues. am I the only one ever to do this? I had exactly less than 15miles on the first and the second one I almost didn't make it back home.

Update on my fuel pump. Took the members advice and bought the whole unit FG0407 as my fuel gauge has been non-working for a long time. Bought it from Rock Auto as it was the cheapest place to buy. Got it in last week and had a chance to change it out yesterday, Easy enough to change, must removed the old unit, greased up the new rubber gasket, pushed it into place and tightened the ring, changed out the new connection , it was not marked with numbers but was colored coded as the old wires were. It all worked fine. Parked vehicle back into the garage and I hear a rattling like the brakes are creaking or the alternator bearing is bad, kind of like that but popping and creaking every few seconds , I put it in park and take my foot off the brake and its still doing it, so I figure its the alternator bearing or an idler pulley, ( sounds just like that). I open the hood, nothing there making noise , sounds like underneath so I crawl under the transmission, and nothing ,but I can hear it, , a baffle in the muffler? no. its coming from the gas tank, I put my ear to the plastic tank bottom and its the pump rattling. Get my stethoscope and take the gas cap off , sure enough its the pump rattling like a bad idler pulley sounds. So I guess buying the best is not good enough. Got Zero miles on the pump. sounds like it could quit anytime.

all I have is the codes in the glove box. it is a EVA code I haven't looked for a RPO I tried to get under it today and put my hand on it or see the top, On such luck, Couldn't even get my arm past the Driveshaft of muffler. Ron

so Use a Delphi or do not use a delphi? How do I tell if it has 2 wiring connectors or just one with out taking it off? How do I determine of it has a Check valve or not? all this is asked by Delphi?

Ok I placed the Pressure gauge on the windshield and drove around town, 30-50 miles an hour, the lowest on the gauge was @45PSI and the highest was about 48PSI fluctuated while moving and steady around 45 while idling. When I got home I took the vacuum hose off and plugged it and the gage grew up near 50PSI never anymore. VIN is 2GTEK19TSY1222104 if someone could help with a pump part number, I am thinking to change to whole unit out.

service sticker says EVA but I can get the Vin ,OK if someone can look it up? its better than having the wrong pump in hand with the bed up. Ron

I see the code in the glove box is for a EVA fuel pump.

Ok, what brand is good for new pump? My fuel gauge is always been a POS and I thought if I ever changed the pump I would change the hole unit. I don't have a lift or transmission jack anymore so I may just tilt the bed.? I see that make about 3 different ones is the code on the build sheet? Tfc or TFU or? Ron

Ok, didn't think about pulling the vacuum off the regulator but I have exactly 45lbs on the gauge I trust at the fuel rail with key on and engine dead, I have exactly 45lbs with engine running and regulator working. so this isn't good, causes for stalling and surging?

Wonder what the Pump pressure should be when running? check it on the fuel rail?

a few more screen shots

I have a 2000 GMC 3 door Sierra Automatic loaded with 170,000 miles, well maintained with records kept. Its been stalling lately and surging enough to be scary in traffic. Also when I start it cold of the morning , I stand beside it and reach in to start and it has been idling low to the point of dying at least once, starts ups are good though and I always allow it to come to temp before driving. Past few days I got in the seat and turned on ignition and stepped on the accelerator before starting to give sensors a voltage value, it didn’t help. Today I changed the fuel Filter and it needed it but I have seen worse, I placed my old scan tool on it and took some screen sots of it while idling, the only code was PO171 that said it was Too lean. I looked for air leaks on the vacuum hoses and purge vale and all along the air intake boots for the MAF sensor to the valve plate , I see no cracks or breaks , nothing. Is there anyone that can look at these screen shots of my scanner and give me a good guess or where to look and how to find my problem? Only major repair on engine was done by me about 6 years ago and I changed the Knock sensors because of detonation and I used OEM sensors and Felpro gaskets, I was a Mechanic for about 25 years in the 80s-90s. Any help would be appreciated

I have a 2000 GMC 1500 that has the 3 knob HVAC , 5 speed blower on left, cold air/hot air one knob center and , air placement knob on right. has AC also. My heater got where it would not blow hot air to the floor and rear seat this winter, very annoying to have only hot air in your face. I had changed the actuator on the bottom of the heater box a couple years ago so I figured it was the one above right of the accelerator pedal, looked to be working while watching it but air never changed, so I ordered a new one. Knowing I may have trouble replacing it as it has a large 2 groove cam on the rear of the actuator. I looked up a few videos online to help, well they were less than satisfying as most people are on YOU Tube, they show more of them selves than a fix. Warm outside today so I decided to change it out, had some trouble getting it out as far as other parts removal first, but the 2 white actuator arms were good shape and turn good,. The new actuator had the position showing as a middle position so I place the control in the middle position too which was to the floor air and it moved to the middle position while watching it. Turned off the power and ignition and removed old actuator., That is where I am at now, I have both of them lying on my bench , they are identical except the original has screws , the Dorman I bought has tabs. The GM one does have a broken main gear thus it does not work right and didn't put the white levers in the correct position when I removed it, I never actually got the new one installed where it was correct, , I moved the levers by hand many times while the actuator was showing the middle up position and still never got it to go all the way left( defrost)or right ( face vents) and if it did it would not come back to center again. So I am asking how do I " time", or "clock" the 2 white levers to the actuator? Did the new actuator "over cam " when it was installed in the wrong position? any tips or tricks would be appreciated. I am not a dunce, I had my own auto repair business thru the 1980s and 1990s, so I know something about mechanic's, just not much about this. Any advise will be taken seriously. Thanks Ron