ridge1

[mlevan]

Hello,
I'm new at this,so I hope L'm pushing the right buttons.I have a 1985 GMC c-2500 with a 6.2 engine.I've had this truck for several years with no problems until now.I get a surge like I'm stepping on and off the gas pedal.When I'm starting out,I start out easy and it takes off like I stepped on the pedal harder.I don't know how else to describe it.I'm new here and any info would be very much appreciated.Thank you

[DmaxMaverick]

Welcome aboard!

You did fine, hitting the right buttons......

Your issue could be one of several causes. First, an air leak can cause this. Air in the high pressure end of the system skews timing. An obstructed or kinked return line can also mess with timing. Next, a cracked or chemically/heat softened section of the throttle cable covering, along with a sticky pump throttle input. And, it could be a tired injection pump, getting ready to leave you. Chase the possibilities in the order of simplicity. Good luck!

[mlevan]

Thanks,I'll check those things you mentioned.I started having problems right after I had Aamco rebuild the transmission,the glow plug light stayed on longer and after the engine started the glow plug light stayed on steady for 40 to 50 secs.,instead of flashing a few times,so I replaced the glow plug relay and that fixed that problem but the surging has gotten worse.I thought maybe there is a electrical problem.We were careful not to disturb anything,but maybe we did.Thank you:(

[Subzilla]

Go even simpler than what Dmax suggested first. Try replacing the fuel filter. I've gotten these same symptoms with a clogged filter which as Dmax described, causes air in the lines.