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My '99 GMC Suburban K2500 w/7.4L has 95K miles on it and has been well maintained. On a cold Montana morning (below zero even) it starts perfectly on the very first crank. It does this any time it's been sitting for a long (8+ hours) period of time. However, if I drive somewhere and park for say 1-6 hours it will crank for a very long time before starting (about 10-15 seconds). When it does start it stumbles a bit as if I had run out of fuel and it's finally reaching the engine. If I park and run in somewhere briefly and right back out it'll start perfectly. I thought it was a fuel problem at first and still would if it weren't for the perfect starting after sitting for a period of time. Anyway, I replaced the cap, rotor, coil, checked plugs and wires, replaced crank sensor, fuel filter, air filter, and finally ended up replacing the fuel pump after none of the other steps helped. The pump was louder than I thought it should be (the hum was steady but loud enough to easily hear even over the running engine sound). The pressure checked out at the lower end of the acceptable range. I have tried cycling the pump multiple times before starting and that doesn't seem to help at all. I also tried removing the gas cap thinking vapor lock may be the problem? I also ran a 2 guage welding cable from the engine grounding directly to the battery negative terminal. Checked connections at all ends of both battery cables, cleaned contacts and even put in a new Optima battery. So, I've got a brand new fuel pump and all kinds of other parts but my problem is still there... Any ideas? The only thing left I can think of is the PCM but I'd feel like an idiot if there's something simple I'm not thinking of. I'm a relatively novice mechanic but have all the tools I could need and am willing to try and learn anything. Please help!
Thanks for the response. I changed the crank sensor already (one of the first things I tried). Checked all wires/cables for corrosion and tightness. Also replaced coil, cap and rotor and I do have spark. Checked distributor tightness while changing cap/rotor and it's nice and tight. No check engine light, no codes in history. I do have a good Snap-On scanner (even though I'm still learning how to use it). Thanks for the response. I changed the crank sensor already (one of the first things I tried). Checked all wires/cables for corrosion and tightness. Also replaced coil, cap and rotor and I do have spark. Checked distributor tightness while changing cap/rotor and it's nice and tight. No check engine light, no codes in history. I do have a good Snap-On scanner (even though I'm still learning how to use it).
I have a similar problem. Cold start: Starts right away most of the time. Every 1 to 4 weeks, cold start will back fire and then be hard to start. Once started, it will shake/vibrate violently and then smooth out after a minute or 2.
Warm starts consistently are hard starts. Requires long cranking to get the engine started.
1999 7.4 liter GMC Suburban K2500, 160,000 milesI have a similar problem. Cold start: Starts right away most of the time. Every 1 to 4 weeks, cold start will back fire and then be hard to start. Once started, it will shake/vibrate violently and then smooth out after a minute or 2.
Warm starts consistently are hard starts. Requires long cranking to get the engine started.
1999 7.4 liter GMC Suburban K2500, 160,000 miles
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Try the fuel pressure regulator. Mine was leaking raw gas through the regulator directly into the intake manifold. Acted like a vapor lock/flooded engine.Try the fuel pressure regulator. Mine was leaking raw gas through the regulator directly into the intake manifold. Acted like a vapor lock/flooded engine.
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Hi!!!! try to change the crank sensor .. but before you change it . check the ignicion coil, all wires ground and positve . star from the battery.make sure they are tigth.in place move one by one to ccheck in case it just holding by o0ne tiny piece o loos. than. set up for ignition timing check the ignition rotor is in place the distribuitor in place and tigth.(check the ignition control module is on the bottom of the ign rotor).get somebody to help you crank the car until theignition rotor points to the piston .no. 1 .after you do all this put everthing back star rhe car unplug the wire from the spark plug no.1 se if you have spark.. you have engine ligth on???
take of the starter and chek the teeth on both starter and flywhel. if somebody o you change the fuel filter check if the arrow points to therigth dirrecion. o take of and blow from one side if is cloge replca it..take of the starter and chek the teeth on both starter and flywhel. if somebody o you change the fuel filter check if the arrow points to therigth dirrecion. o take of and blow from one side if is cloge replca it..
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My
2007 GMC Yukon will not start in cold weather. When I turn the key over
the lights/dash controls come on, but the engine does not turn over at
all. Nothing. Put a new battery in and still does it. It is a random
occurance. Would not start for two days this week so I had it towed to
the dealership and the next morning it starts without the service dept
doing anything??? Bring it home and two days later it does it again???
Any ideas?
pedal gets hard when turned of because they are power brakes plus theres no vaccum try bleeding the brakes if theres still a problem check the master cylinder and fluid level when brakes wear down they require more fluid but try first bleeding remember start at pass rear driver rear and pass front and last driver front
this sounds like you have a problem with the electric fuel pump sticking, that would be where i would look, when u turn the key on with the windows up do u hear a humming noise for about 3 seconds? if not the fuel pump is the problem.
I HAD THE SAME PROBLEM WITH MY 1999 GMC YUKON WITH THE 5.7 ENGINE HAVING TO JUMP START ALL THE TIME TO GET IT RUNNING, THE PROBLEM WITH MINE WAS THE FUEL PUMP HAD TO BE REPLACED, EVEN WHEN I REMOVED THE PUMP AND TURNED THE KEY FUEL PUMPED OUT BUT WAS NOT ENOUGH PRESSURE TO GET AND KEEP THE ENGINE RUNNING.I ALSO TRIED STARTER FLUID, THE ENGINE WOULD RUN UNTIL THE FLUID BURNED OFF.SO THE SOLUTION FOR MY TRUCK WAS THE FUEL PUMP AND NOW ITS STARTING LIKE A CHAMP
sounds to me like leaking injectors or fuel pressure regulator. Think about it -- you have puff of smoke (rich condition) and on a cold morning after sitting 8 hours theres no such thing as too much fuel. after sitting 15 minutes the rate of leak down isnt enough to flood it. but in 1-6 hours enough fuel leaks down to the cylinders to flood it (engine still warm enough to not be needing that amount of fuel without stumbling and chocking on it)
Most likely the power steering system is a little low on fluid so it's pulling a little air when it's that cold. Check and see if that is the case and top the system up, should take care of the problem. Good luck
On the 1999 - 2000 5.7 vortec engines the distributor gears wear causing the timing to change 2 or more degrees. The ecm is designed to shut down at 2 or more degreedifference. This is in a GM bulletin that recommends replacement at 160k miles. Mine went out at 150k miles. Very similar driving symtoms until it quit running. Both cam sensor codes were set on mine though, not the crank sensor.
Thanks for the response. I changed the crank sensor already (one of the first things I tried). Checked all wires/cables for corrosion and tightness. Also replaced coil, cap and rotor and I do have spark. Checked distributor tightness while changing cap/rotor and it's nice and tight. No check engine light, no codes in history. I do have a good Snap-On scanner (even though I'm still learning how to use it).
Same truck/thing@204k miles. Curious about solution.
I have a similar problem. Cold start: Starts right away most of the time. Every 1 to 4 weeks, cold start will back fire and then be hard to start. Once started, it will shake/vibrate violently and then smooth out after a minute or 2.
Warm starts consistently are hard starts. Requires long cranking to get the engine started.
1999 7.4 liter GMC Suburban K2500, 160,000 miles
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