[99LS1500]

Guess I should have known something was coming......got almost 800 miles on her since the tranny install and she was running, driving & shifting great with easy start ups. Then I noticed some small things happening
1] a slight stall at idle but the engine never completely stalled out when letting the truck warm up
2} She stalled out 2 times at the same stop sign on Monday and Tuesday but restarted easy and ran fine the rest of each day with no other issues.
3} Wednesday morning, starts, idles and runs fine but that same occasional engine stall is there but the engine never stops. Then I noticed a longer & harder shift going into 2nd gear after leaving a red light from a complete stop but when I checked my trans fluid all was good. Both times the truck rode and shifted fine the rest of the day.
4} Wednesday afternoon, starts easy and idles as it's been doing, then when pulling out of my neighborhood from a stop sign she poof-poofs and loses power as though shes running out of gas. The more I pedal her for gas the worst it runs under power until the engine stalls. It will crank all day long but wont start. I scanned it and it threw a PO0122 which I think has something to do with the TPS. So I go buy a new TPS and install it and still nothing but a good strong crank but no starting.

Whats the easiest way to check for a bad fuel pump ????
Any other suggestions would be greatly appreciated !!!!!!!

 

[apcnc]

Have you checked the pressure, regulator? Is it running rich? Wiring to TPS ok? Tension on the TPS?

 

[99LS1500]

No, I normally leave the technical stuff I've never dealt with before in the hands of my mechanic but after watching a few you tube vids I'm pretty confident I can at least do a fuel pressure test on her. As for the TPS, no wire tension, I installed a brand new TPS, checked the wiring and connector a few times and saw nothing that raised a brow.

1 more thing I failed to mention.....when driving up hill I noticed the truck would buck a little as if it was not getting gas. Isn't that normally caused by fuel starvation due to a failing fuel pump ????

 

[apcnc]

Could be wires. They tend to do that under a load going up hill and such. Still no other codes?

The tps usually has a slight tension on it when you install it. Make sure the shaft is behind the grove rotate it into place. At that point there is slight tension. If not behind it the throttle will open and the shaft will turn a bit before turning the tps.

 

[99LS1500]

29 degrees out side this morning with a chill wind blowing so I think I'll wait until the wind stops and the outside temp is higher before going under the hood again. As for the TPS install, the shaft is D shaped and I removed it making sure it was installed correctly 2 times yesterday. I was very careful not to force it in place and made sure it went on easy, flush and lined up before re-installing the 2 screws.
I did notice the wiring around the connector was a bit hard but not brittle with no signs of burning so it didn't raise a brow.

 

[apcnc]

Wow! It was 22℉ down here this morning.

 

[99LS1500]

Got back under the hood today and double checked my relays /fuses. Purchased a Fuel Pressure Test Kit and connected it to the fuel pressure nozzle thinking it would at least blast my hand with some gas when connecting and it didn't spray a hint of gas which raised my brows. Made sure the connection was tight then turned the key to the ON position 5-6 times and got Zero pressure. Cranked the engine over 5-6 times and still got Zero pressure. Pulled the vac line off the Pressure Regulator and no gas tricked out so it's functioning properly. So at this point I'm thinking the fuel pump crapped totally out on me which would explain why the truck would sometimes slightly buck as though it was starving for gas when going up hill. It was obviously on its way out 800 miles ago when I 1st noticed the slight issue when driving up hill. Guess I'll be ordering a new GM AC Delco Fuel Pump and Fuel Filter this week.

 

[apcnc]

Did you swap the relay? That a strange that there is no pressure at all. Could be the line rotted out from the pump to the housing dumping the pressure back in the tank if it's running that is. Make sure you have power on the plug before reinstalling the tank with the new pump.

 

[99LS1500]

Yes, I forgot to mention I swapped the relays. I thought it was strange too that I got ZERO pressure until watching a few you tube vids that showed other owners with the same issue. I ordered a new GM pump complete with the new plug harnesss . Figured I might as well have it done right with the GM Parts.