what would cause a 1999 Chevy C3500 with the 5.7 engine to fluctuate rpm between 50 and 60 miles an hour backfire and almost stall? I've gone as far as replacing the fuel pump with a new.

Asked by cad442 Feb 06, 2015 at 10:16 PM about the 1999 Chevrolet C/K 3500 LB RWD

Question type: Maintenance & Repair

2 Answers

120

Did you do the filter? Could just need a tune up or maybe a maf sensor. Is it putting out any codes?

thank you for your answer Steve, I changed the cam position sensorthe truck ran great for about 15 minutes with lots of power then act it up the same way check engine light was on rpm stop back down computer like reset itself and was backfiring , I change the cap and rotor ran smoothly not as much power but no check engine lights or rpm fluctuation so far I will know on Monday when I get to drive it further but got it past 70 mph I have yet to see if I resolved the sensor issue???

Your Answer:

CarGurus Experts

  • #1
    Joe_2019
    Reputation
    420
  • #2
    Gene Arnett
    Reputation
    380
  • #3
    Keith Massey
    Reputation
    220
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Chevrolet Silverado 2500HD
28 Great Deals out of 1,611 listings starting at $8,999
Used Chevrolet Silverado 1500
176 Great Deals out of 7,546 listings starting at $7,777
Used GMC Sierra 1500
127 Great Deals out of 7,869 listings starting at $5,500
Used Ford F-350 Super Duty
52 Great Deals out of 1,448 listings starting at $7,000

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.