1995 Yukon 4x4 5.7 TBI Erratic / Surging Idle

[JT357]

I've been having a problem with my 95 Yukon TBI 4x4 170,000 miles. The engine runs very well and the erratic idle shows up when it's warmed up sitting at a light. It will normally idle at 500 rpm but will drop to 450ish and then up to high 500's. Giving it some gas seems to reset it for a while until it eventually begins again. It has died on me 3 times so far. Any help would be gladly accepted.

Another issue is that the passing gear stutters or stalls sometimes. I don't think that it's connected to the idle problem any ideas or is it?

I've used all AC Delco parts on the Yukon. I've replaced the EGR, IAC, TPS, MAP, O2 sensor, catalytic converter, both temp sensors, and distruibutor assy, wires/plugs and rebuilt the Throttle body with new injectors. I added the 14 lb spring into the Throttle body but it had no effect. It also has a new alternator and a new battery. I've looked for quite a while for a vacuum leak and only found a small one and of course after repairing it it had no effect. I changed the intake also due to the coolant leak problem and installed an edelbrock intake. Not all the parts I replaced were strictly due to the idle problem, the vehicle previously was not maintained at all.


I've researched as much as possible and some people have narrowed it down to a low fuel pressure issue from the fuel pump. In the forums some of the responses have been that if it is a fuel pump problem it wouldn't run at all. Any ideas on this? If I do have to change the fuel pumop are there any suggestions on which brand or a P/N? Like most people I would rather not pull the gas tank more than once. I like to use AC Delco but I've seen a few bad reviews for the AC Delco fuel pump. Any suggestions for a fuel pump and are the AC Delco fuel pump bad reviews to be ignored?

 

[dkknaebel]

Have you checked Rock Auto for fuel pump? They have the whole assembly so you can replace everything at once.

 

[Kelsda]

I've been having a problem with my 95 Yukon TBI 4x4 170,000 miles. The engine runs very well and the erratic idle shows up when it's warmed up sitting at a light. It will normally idle at 500 rpm but will drop to 450ish and then up to high 500's. Giving it some gas seems to reset it for a while until it eventually begins again. It has died on me 3 times so far. Any help would be gladly accepted.

Another issue is that the passing gear stutters or stalls sometimes. I don't think that it's connected to the idle problem any ideas or is it?

I've used all AC Delco parts on the Yukon. I've replaced the EGR, IAC, TPS, MAP, O2 sensor, catalytic converter, both temp sensors, and distruibutor assy, wires/plugs and rebuilt the Throttle body with new injectors. I added the 14 lb spring into the Throttle body but it had no effect. It also has a new alternator and a new battery. I've looked for quite a while for a vacuum leak and only found a small one and of course after repairing it it had no effect. I changed the intake also due to the coolant leak problem and installed an edelbrock intake. Not all the parts I replaced were strictly due to the idle problem, the vehicle previously was not maintained at all.


I've researched as much as possible and some people have narrowed it down to a low fuel pressure issue from the fuel pump. In the forums some of the responses have been that if it is a fuel pump problem it wouldn't run at all. Any ideas on this? If I do have to change the fuel pumop are there any suggestions on which brand or a P/N? Like most people I would rather not pull the gas tank more than once. I like to use AC Delco but I've seen a few bad reviews for the AC Delco fuel pump. Any suggestions for a fuel pump and are the AC Delco fuel pump bad reviews to be ignored?

I know a lot of mechanic shops won’t even entertain using aftermarket fuel pumps especially if your keeping it dealer item gmpartsdirect for your truck is around 275.00 for both pump and strainer,there is also different grades of delco some are cheaper as in quality if buying other than dealer good luck

 

[JT357]

Thanks for the responses. I'll give gmpartsdirect a look and see what they have for me. I looked at Rock Auto and I wasn't sure which brand was the better one.

 

[JT357]

Thanks for the responses. I'll give gmpartsdirect a look and see what they have for me. I looked at Rock Auto and I wasn't sure which brand was the better one.

So to conclude what was causing my Yukon to idle so badly was the PROM. For me it was a PROM someone had put in that was for a V6. It took a while to run the PROM code to determine what was in there. I ordered a new PROM and the idle is fine.

 

[Squirrelsmith]

I had a jeep that did this for 5 years nobody ever figure out what it was, mine never died though. Try putting it into park next time and see if that also "re sets" it. Might give someone a clue?

 

[haks310]

If you are still looking at fuel pumps go with either the AC Delco or Delphi. From my research it looks like the AC Delco one is just a rebranded Delphi. I just did my fuel pump two weeks ago and purchased a Delphi for $186 out the door from AutoZone, same price for an AC Delco one if ordered through Amazon. The Delphi unit also had a sheet in there which had an AC Delco logo printed on it which confirmed my research. Don't think it was the instruction sheet, maybe some fuel warning or something.

Shoot me a PM or start a new thread once you do decide to do the pump and I will walk you through the whole ordeal and needed parts and tools.