95 Sierra 5.7 engine hiccups shifting into 2nd

[KenTaz]

My name is Ken. My 95 Sierra 5.7 engine hiccups when the transmission shifts to second gear. This was happening for quite some time (over 1 year). It only happens after startup on the first shift. It runs fine after the first hiccup until you shut the engine down for a while and restart it. After some time of this happening, the fuel pump died and needed replaced this past November. After the fuel pump was replaced it ran great, so I figured that had been the problem all along. Now, 8 or 9 months later, it is doing the same thing again. I have replaced the fuel filter again. Very frustrating.

Thanks so much,

Ken

 

[riverbanks]

fuel pressure regulator,worth a check

[KenTaz]

 

23 hours ago, riverbanks said:

fuel pressure regulator,worth a check

Yeah, I was thinking about the regulator also. It just doesn't make sense that everything would be fine with a new pump for 8 months. Thanks for your reply!

[riverbanks]

Think about it,new pump, higher pressure,less strain on a used regulator,new pump,now a little aged, regulator back in play

[KenTaz]

On 9/2/2019 at 12:45 PM, riverbanks said:

Think about it,new pump, higher pressure,less strain on a used regulator,new pump,now a little aged, regulator back in play

Sorry riverbanks, it's been some time since I replied to this post. The issue got much worse. It started misfiring every time you hit the throttle while driving, making it undrivable. I rebuilt the regulator, cleaned and made sure that the injectors were in good working order and replaced the tps while I was in there. It seamed to make a difference, but it still misfired when it shifted into second, for a few days, then it started getting worse again. I plugged the vacuum line going to the egr from the solenoid, thinking that the egr could be bad. That also made a difference, so I replaced the egr valve and the vacuum lines going to it. Again, it helped for a couple of days, but then it started misfiring all the time again. I had the fuel pump replaced AGAIN, but it misfired bad right away. I parked the truck for an hour to gather my thoughts. When I restarted the truck it ran great for about 2 weeks, but started the whole misfiring process all over again. I sprayed starting fluid around the throttle body and the vacuum lines, but I didn't get any fluctuations in the rpm. I'm ready to just get rid of it soon, lol.

[KenTaz]

Still looking for an answer to my issue. The engine starts running horribly after the automatic transmission shifts into second gear, almost stalling, and misfiring constantly. If I drop the trans back into 1st the engine runs fine with no hesitation or misfire. Could this be a ECM problem? I still am not getting a check engine light. 95 GMC k1500 5.7 automatic.