Help!!! 99 yukon hard starting

[ajm108]

Hello All,

Here is my story I have a 99 Yukon with a 5.7l and over the summer it felt like it started to misfire ,the plugs were fairly new so I changed the cap,rotor and wires that seem to take care of it.
Then about a month ago it was giving me trouble starting so I changed the plugs that helped a little then it had a couple of codes p0161 and p0135 so I changed the sensors and still the same thing and the check engine light comes on and off but if I put jumper cables on it it starts with no problem The battery showed to be a little weak and that was replaced as well and also the PCV,fuel filter and airfilter were replaced as well as new plugs but yet the same thing its hard to start and after awhile it starts and the truck never not started but at times it needed to be jumped while it is running it runs fine.
Any Ideas
Thank You for any help

 

[Razincayne]

I was going to make a guess and say that maybe your Fuel Pressure Regulator is going south on you or maybe a dirty MAF but you say once you put jumper cables on it, it starts right up and runs fine. What is your volt guage in your truck reading? Should be reading 14.0 to 14.5. The reason I ask is a few weeks ago I started throwing code P0161. I did some research and found that low voltage can throw this code. I was reading around 13.0 according to my guage. I did the obvious and did a good cleaning on my battery cables and now I am reading the 14.0 to 14.5 and the truck hasn't threw the code in several weeks. Mine never was difficult to start as yours is but, does crank over a little faster now. Still might try cleaning your MAF if you haven't done so already and check your battery cables. Good Luck

 

[ajm108]

When I changed the battery yesterday the negative terminal was alittle dirty so I cleaned that up and I will try cleaning the maf tonight.

Thanks for your help:thumbsup:

 

[fyremanpat]

Buy MAF cleaner. Dont use anything else...I found out the hard way

 

[ajm108]

Thanks