1994 GMC Sierra Sputtering problem

dimples0925 · 09-03-2009, 01:46 PM

I have a 1994 GMC Sierra with the 350. It has started sputtering only when
taking off from a stop, and now it will die out when this sputtering happens.
Have to pump the gas peddle to get the truck running again and stay on it to get going. Once the truck is moving it acts fine. This also happens very
sporadically, not all the time. When acting up like this it also has dark smoke
coming from the tail pipe. A few months ago we did a complete tune up. A month and a half ago we had the intake gasket changed on the truck. This started a few weeks ago and is getting much worse. We sprayed around the intake as well as the TBI while the truck was running to look for leaks around the gaskets and found nothing. I also used fuel injection cleaner to see if this would help the problem. The check enging light has been going on and off. Never on all the time. I know I should have it scanned to see why the light is on but the auto stores around me don't have computers that are compatible for the age of my truck, trying to find someone that has one. Until then do you have any suggestions as to what we might check next? Thanks

**octaneman** · 09-04-2009, 01:26 PM

Hi dimples0925

Test the fuel pump by hooking up a fuel pressure gage, take note of the pressure at idle then under load having someone hold down the brake pedal while putting it in drive. If the fuel pressure is not within specs the fuel pump or fuel regulator needs to be replaced. Also, hook up a vacuum gage to test for vacuum leaks, testing for leaks using old fashioned methods sometimes do not yield the complete picture and it requires further investigation. Should the check engine light come on again, have the code extracted as soon as possible, the code can pinpoint which engine circuit needs attention. To extract the codes, there is a method by jumping 2 pins using a cotter pin on the ALDL connector without using a scanner. Do an on line search for GM code extraction, there is plenty of information out there to show you how it's done.

post back your findings.

**Raylo** · 09-04-2009, 02:04 PM

Possible sticking EGR. But like Octaneman says, check the code.

dimples0925 · 09-05-2009, 09:55 PM

Thanks for the answers. After the remark on EGR I did research on this and the symptoms fit and made sense since the guy that did the intake gasket did not put in a new gasket. I have dealer books on this truck so I used the paperclip method to scan any codes that came up. The only code that came up was the EGR. We took it off, cleaned with carbon cleaner, and put in a new gasket. As my problems were sporadic I am not positive this has worked but my thoughts are that it worked. Been driving around without any trouble and I have found that my truck has an increase in power that I had not realized it lost until doing this work today. I think I have my truck back!!!!!!! Thanks again. Both of your inputs came in handy and made me search on the computer scan as well as the EGR.

**Raylo** · 09-06-2009, 05:35 AM

Good job Dimples! Glad you could benefit from my previous experience with the same problem on my old S10 pickup 4.3. At least something good came out of it.

09-03-2009, 01:46 PM	#1 (permalink)
dimples0925 Registered User Join Date: Sep 2009 Posts: 2 OS: xp	1994 GMC Sierra Sputtering problem I have a 1994 GMC Sierra with the 350. It has started sputtering only when taking off from a stop, and now it will die out when this sputtering happens. Have to pump the gas peddle to get the truck running again and stay on it to get going. Once the truck is moving it acts fine. This also happens very sporadically, not all the time. When acting up like this it also has dark smoke coming from the tail pipe. A few months ago we did a complete tune up. A month and a half ago we had the intake gasket changed on the truck. This started a few weeks ago and is getting much worse. We sprayed around the intake as well as the TBI while the truck was running to look for leaks around the gaskets and found nothing. I also used fuel injection cleaner to see if this would help the problem. The check enging light has been going on and off. Never on all the time. I know I should have it scanned to see why the light is on but the auto stores around me don't have computers that are compatible for the age of my truck, trying to find someone that has one. Until then do you have any suggestions as to what we might check next? Thanks

09-04-2009, 01:26 PM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 566 OS: WINXP	Re: 1994 GMC Sierra Sputtering problem Hi dimples0925 Test the fuel pump by hooking up a fuel pressure gage, take note of the pressure at idle then under load having someone hold down the brake pedal while putting it in drive. If the fuel pressure is not within specs the fuel pump or fuel regulator needs to be replaced. Also, hook up a vacuum gage to test for vacuum leaks, testing for leaks using old fashioned methods sometimes do not yield the complete picture and it requires further investigation. Should the check engine light come on again, have the code extracted as soon as possible, the code can pinpoint which engine circuit needs attention. To extract the codes, there is a method by jumping 2 pins using a cotter pin on the ALDL connector without using a scanner. Do an on line search for GM code extraction, there is plenty of information out there to show you how it's done. post back your findings.

09-04-2009, 02:04 PM	#3 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 525 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: 1994 GMC Sierra Sputtering problem Possible sticking EGR. But like Octaneman says, check the code.

09-05-2009, 09:55 PM	#4 (permalink)
dimples0925 Registered User Join Date: Sep 2009 Posts: 2 OS: xp	Re: 1994 GMC Sierra Sputtering problem Thanks for the answers. After the remark on EGR I did research on this and the symptoms fit and made sense since the guy that did the intake gasket did not put in a new gasket. I have dealer books on this truck so I used the paperclip method to scan any codes that came up. The only code that came up was the EGR. We took it off, cleaned with carbon cleaner, and put in a new gasket. As my problems were sporadic I am not positive this has worked but my thoughts are that it worked. Been driving around without any trouble and I have found that my truck has an increase in power that I had not realized it lost until doing this work today. I think I have my truck back!!!!!!! Thanks again. Both of your inputs came in handy and made me search on the computer scan as well as the EGR.

09-06-2009, 05:35 AM	#5 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 525 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: 1994 GMC Sierra Sputtering problem Good job Dimples! Glad you could benefit from my previous experience with the same problem on my old S10 pickup 4.3. At least something good came out of it.