sluggish acceleration, rough idel

[hntrgrn04]

So I had problems starting the truck all the time, once got moving would not want to take off and when it did it would hesetate. did some reading and was suggested to replace fuel pressure regulator. So I did still had same problem, then while ideling in the drive way truck shut off and won't restart. changed fuel filter, still no luck. someone told me that the fuel pump was not putting out enough pressure to deliver fuel to motor, if this is true do I need to change fuel pump.....

 

[clkelley]

Welcome to the neighborhood!

We are going to need a little more info. First about your truck, what year make and model, etc. How has the maintenance been kept, meaning, when was the last time the plugs, etc were changed. Those types of things will help us better help you to narrow down your issues.

 

[lesterl]

Try some gas or carb cleaner into the intake, will it start then?

 

[hntrgrn04]

update

Ok so I have a 99 4 door with 230k miles I have had the truck for 4 yrs now. I changed the plugs about 3mo ago keep up with general maintenance as needed do just about all repairs at my level as much as possible. just in the last mo I have had the problem starting the truck. sometimes I had to pump the peddle for it to start, or it would take a min or two before it would start. sometimes taking off from a stop it would hesetate then normal acceleration, or if I put it in nuetral it would reave up then as soon as I put back in drive the hesetation. So like I said I changed the pressure regulator still did samething just not as often, it ran for two days then sitting in an idle it died and won't start now. I am pretty sure its the original pump I can hear it hum like before when you turn the key but just not as loud as before. What else ???

 

[hntrgrn04]

Oh ya also did the gas and starter spray in the carb it would run with the presence of the fluids then would die once burned off, it's got the injectors inside of the intake plenum. Looked at those they didn't seem bad, cleaned with carb cleaner one by one, sure they spider assembly is original (just so expensive).

 

[clkelley]

The pump is probably the source of the issue. But definitely the fuel filter as well. You are just starving the truck at idle, but once the fuel is flowing through the filter and pump at speed, it seems to be a little better, but then when it comes back down it almost stops or stops completely.

I would replace the filter first, then if it persists then change the pump.

 

[hntrgrn04]

I thought the samething so I changed the filter that same day no change killed the battery trying to start, so any suggestion on what type of feul pump to buy.

 

[squeasel]

I suggest a couple of tests if possible. First, re-examine your newly installed spark plugs for fouling. And check the fuel pressure at the test valve near the distributor. The first needs no tools that you don't already have. It doesn't account for all your symptons but sometimes there are multiple problems. The second requires a tester but perhaps that can be borrowed from a friend or an auto parts store if you don't have one already. A standard reading is 60-66 psi according to my Haynes manual (the manual is NOT a recommended purchase). Currently I have a number of the same symptoms (trouble with cold-start, weaker than normal acceleration, and the engine running less smooth than expected). I changed spark plugs and acceleration and smoothness returned but it still looks like I have a cold start issue (BTW my fuel pressure is 55 psi slight below spec and may be the cold start cause). Best wishes.

 

[lesterl]

Charge the battery, once done, jump start with a donor vehicle. Battery resting voltage is around 12v, even lower when cranking so pump doesnt get full voltage for full output. When engine is running the alt keeps system voltage around 14v for higher output. Signs of weak pump IMHO, and also causes of hard cold start.

Pressure test the system......

 

[bdressel]

My new Tahoe exibits the same and I understand the RVC system but do any of you experience sluggish exceleration and shifting issues after the voltage drops? The throttle response and shifting is perfect until the RVC takes over and drops the voltage to 10-12V. I have had them check it but they say they can't recreate the throttle and shifting issue. Sure!

 

[lesterl]

What is RVC?

 

[squeasel]

RVC is Regulated Voltage Control and if my info is correct, started on GM products in 2004 so it is a bit mis-placed in this sub-forum.

 

[lesterl]

My 06 sierra had that I suspect since I kept a digial meter on it at all times, kinda freaky.

That being said, my 95 when the battery gets charged it will drop a few volts based upon the guage on the dash, depends if it is accurate or not.

 

[hntrgrn04]

ok so this week I will looking for replacement fuel pump, any suggestion on where and what brand would be good to install and is there one suggested not to install. Or is there one better than another, short of getting one from a dealership we have and autozone, oriely's, pep boys and advanced auto part for non dealer part stores.

 

[lesterl]

Use an ACDelco, or Delphi assembly, short of that, a Walbro unit.....

http://www.amazon.com/Delphi-FG0089...HZ5K/ref=sr_1_1?ie=UTF8&qid=1334718270&sr=8-1

$143 from Amazon - FREESHIPPING, $156 +shipping from www.rockauto.com

 

[hntrgrn04]

Thanks for the help I will go that route cause I have heard the same thing to use AC Delco.

 

[hntrgrn04]

Ok so hows this I jump started the truck last night took a little bit but it start. took a few time but eventually she stayed on, let her run in driveway for about 15 min took her on a test drive. Seemed to run ok but then the sluggish acceleration started, it almost seems like either I am not getting enough air or too much, if I accelerate she start to bog, let up on the peddle and reengage and go smooth. So if I give her gas right away it boggs let off for a few seconds and takes of slow into a normal acceleration. At one point a while back check engine light came on after I changed pressure regulator, was told had bad O2 sensors on Bank 2. parked her for a bit light went away but same acceleration, any thoughts........

 

[clkelley]

Clean the MAF and throttle body, change the O2 sensors and then see if the issue persists.

Also, I know this may sound crazy, but I have seen a couple of vehicles exhibit similar symptoms when the tranny fluid was low. Apparently the tranny fluid not providing proper line pressures, etc would cause added strain on the engine and not allow it to run or shift properly.

MAYBE! Not saying that is the issue here, but I have seen about three trucks that have had issues with the tranny that made folks think there was something wrong with the engine as a result of similar symptoms.

 

[hntrgrn04]

tranny would be something I will def check I did have it rebuilt about two months ago thanks let you know..

 

[hntrgrn04]

well still having prob, changed plugs but did notice that one plug had some water in the plug when I pulled it also when I do get truck running it puts out white smoke but no water in oil...hmmmm