Surging

Tiny
TIM0920
  • MEMBER
  • 2001 GMC SIERRA
  • V8
  • 2WD
  • AUTOMATIC
  • 99,400 MILES
I have tried changing the 02 sensors, fuel pump, fuel filter, and egr valve. The problem still having same problem. Under acceleration the vehicle. Surges like I was pushing on and off on off on off. Please let me know if there is something I am missing. I am thinking fuel pressure regulator. Thank You in Advance.
Saturday, November 22nd, 2008 AT 1:56 PM

10 Replies

Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
Unplug the mass air flow sensor and see if the surge goes away. it will run a little funky with it unplugged but you should be able to tell. If it runs better replace the MAF. Here is a guide to help us.

https://www.2carpros.com/articles/engine-surges

Please run down this guide and report back.
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Sunday, November 23rd, 2008 AT 4:44 AM
Tiny
MICHAELJDEAN88
  • MEMBER
  • 2 POSTS
  • 1997 GMC SIERRA
  • V8
  • 4WD
  • AUTOMATIC
  • 133,000 MILES
When I press on the accelerator the engine surges. It seems to me its not getting enough fuel and when it starts to surge I lose oil pressure. I put a brand new fuel pump, 3 actually, in it, changed fuel filters regularly, new plugs and wires, mass air flow sensor, throttle positioning sensor, and new fuel pressure regulator. I drained the tank and cleaned it out thinking I might have had a dirty tank. I'm considering putting a brand new tank with a new pump and sending unit. What should I do next because I'm not what is wrong with the truck? Thank you for the assistance.
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Wednesday, August 14th, 2019 AT 10:06 AM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
When ignition switch is turned to ON position, PCM/VCM turns electric fuel pump on by energizing fuel pump relay. PCM/VCM keeps relay energized if engine is running or cranking (PCM/VCM is receiving reference pulses from ignition module). If there are no reference pulses, PCM/VCM turns pump off within 2-20 seconds after key on.
As a back-up system to fuel pump relay, the oil pressure switch also activates fuel pump. The oil pressure switch is normally open until oil pressure reaches about 4 psi (.28 kg/cm2 ). If fuel pump relay fails, the oil pressure switch closes when oil pressure is obtained and operates the fuel pump.
Cranking time will be longer if fuel pump does not receive current until oil pressure switch contacts close.
Oil pressure switch may be combined into a single unit with an oil pressure gauge sending unit or sensor.
PCM/VCM monitors fuel pump circuit between fuel pump relay/oil pressure switch and fuel pump, enabling PCM/VCM to determine if fuel pump is being energized by fuel pump relay or oil pressure switch. A failure in this monitored circuit results in the setting of a related diagnostic trouble code in PCM/VCM memory.
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+3
Wednesday, August 14th, 2019 AT 10:06 AM (Merged)
Tiny
MICHAELJDEAN88
  • MEMBER
  • 2 POSTS
Ok thanks for the help by the way. I know the trouble codes I've been getting have been for the O2 sensors and the other code is a random misfire. Is it possible that if either the fuel pump relay or the oil pressure switch are failing could that cause a random misfire? I checked for vacuum leaks and replaced my plugs and wires because I wasn't sure what cylinder was misfiring. Someone had mentioned to me that the egr may be bad. Would a faulty egr valve cause these problems? Once again thank you for the assistance.
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-1
Wednesday, August 14th, 2019 AT 10:07 AM (Merged)
Tiny
GMC_3500
  • MEMBER
  • 2 POSTS
  • 1998 GMC SIERRA
My truck is a diesel turbo 6.5 it seems to run fine but when I am driving it it seems to have a surge where the truck has more power for about 1-2 sec. And when idling it seems to also surge. Changed oil and filter. And I also changed my fuel filter. I can not figure this out as we do not know a whole lot about diesel engines.
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Wednesday, August 14th, 2019 AT 10:07 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Injector pump may have an issue or the injectors may be clogged.

I reccomend letting a shop check it for you as it is more complicated than you think and not for a do it yourself unless you have expierence

Roy
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Wednesday, August 14th, 2019 AT 10:07 AM (Merged)
Tiny
GMC_3500
  • MEMBER
  • 2 POSTS
Ok. The vehicle is not shutting off at all. He just came in from checking the coolant pressure and he said after idling the pressure goes 20+. We suspect a blown headgasket. Could this be what is causing the problems we are having?
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Wednesday, August 14th, 2019 AT 10:07 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Absolutely. I would resolve that issue first. Make sure you check the heads closely, they are common for cracking.

Roy
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Wednesday, August 14th, 2019 AT 10:07 AM (Merged)
Tiny
PSTONE1959
  • MEMBER
  • 1 POST
  • 1998 GMC SIERRA
  • V8
  • 2WD
  • AUTOMATIC
  • 249,000 MILES
I have a 1998 GMC serria 1500 2wd. In high gear driving down the road the truck surge until you reach about 2000 rpm( 45mph-65 mph) then it stop until it get back un the rpm range. You can be driving along in high between 45-65 mph tach jump from 1800 to 2100 rpm continue until you reach 65 mph. Idle good and do good in 1-3rd gear. Pulling a trailer or under a load it drive good and shift good.
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Wednesday, August 14th, 2019 AT 10:07 AM (Merged)
Tiny
BIGALLEN19
  • MEMBER
  • 0 POST
Replace the MAF cost me $101.00 all set.
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Wednesday, August 14th, 2019 AT 10:08 AM

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