2007 gmc canyon sputters like it is going to cut off when applying brakes sometimes hard to start. just changed plugs and air filter . could it be brake booster or something else
if I say possible servo booster is faulty,surely you will feel it on the brake pedal ( stiff ),or the engine running would be erratic.the other alternative situation is the pipe( hose ) which is connected with inlet manifold and servo booster and inside has the check valve probably is faulty. Test : off engine,pump brake pedal several times till gets stiff. Keeping your foot on brake pedal start the engine and if your servo works fine then the pedal goes a bit down,if not will not move at all. If the engine is running erraticly then with engine off, remove the pipe connecting manifold and servo block the pipe you remove from servo side,block it and start the engine,If engine run fine,then you must confirm whether is the servo or the check valve hose. For the check valve hose how to check,just put in your mouth the servo side pipe and blow into,if the air goes in the engine means that the check valve is broken and you must renew the pipe with check valve,if on blowing into will not allow air to get through,means is ok and the servo is the fault. Good luck.
2007 GMC Canyon...
on Jan 03, 2013