Trouble Starting/ Engine dies once in awhile while stopped at a light

Asked by Mar 11, 2016 at 03:53 PM about the 1999 GMC Sierra 1500

Question type: Maintenance & Repair

My truck will start just fine after sitting for awhile (i.e. overnight), but if the engine is shut off and I try to start it back up in 5 minutes, 10 minutes, 30 minutes later, its hard to start and takes a little (5 sec).  Always starts eventually. Also, when I am stopped at a light, I will feel the truck is about to die, but if I let off the brake it will catch itself and be fine.  Any ideas on what it could be...I'm thinking fuel pump, but after looking at some of the answers on the site to similar questions, it seems like that's not always the case. Also its not the battery...its brand new.

2 Answers

20

If you let off the brake and it acts differently, then maybe you have a vacuum leak in your brake booster line.

71,245

Hard starting is an indication of leaky fuel injectors, spider lines, and fuel regulator. What size is the motor? So what you do is hook up a fuel pressure gauge to the Schrader valve, then just cycle the key on off until it builds up pressure, should be 56 to 63 lbs. then let it sit with the key off, now just watch the gauge for 3 minutes, the fuel pressure should not drop off more than 5 lbs. If it does, then the injector assembly would need to be replaced as a unit.

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