1999 gmc yukon loss of power
#1
10-27-07, 12:11 PM
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1999 gmc yukon loss of power
when i press the gas going up a hill or passing the car almost stalls light pressure on pedal and idle fine, replace the bank 2 sensor cat converts, dist cap spark plugs,rotor cap,added fuel treatment what else could it be???? p0305 last code
#2
10-27-07, 03:13 PM
Fuel filter, or fuel pump or anything else in the fuel delivery system where there just is not ENOUGH fuel. Fuel pressure can be checked.
#3
10-27-07, 03:46 PM
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A bad PCM ground will cause this. Check the ground, which is probably located on the front of the passenger side cylinder head. Remove it and clean any rust theat mey be on it, then put it back on. The most likely cause for this DTC is the following:
a mechanical failure causing low cylinder compression.
a fuel leak at the high pressure fuel injection lines or injection nozzles.
a fuel injection nozzle stuck closed. Could be a bad spark plug, plug wire, injector. Also, it could be too tight of clearance between the valve stem and valve guide. I copied and pasted this right from GM's online Service Information:
The vehicle may exhibit a SES Light due to a P0300 and misfire. If the misfire is related to the information below, it will typically happen while cruising uphill, pulling a trailer or on hard acceleration and then stop misfiring shortly after returning to an idle. Typically, cylinders 3,4,5 or 6 will be the ones to experience this.
Remove the valve cover, valve springs and valve seals on the effected cylinder or cylinders. A small wire tie or rubber bands can be placed in the valve stem keeper groove to prevent the valve from falling into the cylinder. Rotate the valve while moving it up and down in the guide to see if it binds. If a binding valve is found, remove both cylinder heads and use either of the following methods to increase the stem to guide clearance:
• Send the head out to a machine shop and advise them to increase the valve stem to guide clearance to 0.002 inch per guide.
• Hone the guide with a 9 mm hone, such as Snap On BCG249, until a clearance of 0.002 inch is obtained. This will usually take about 4 strokes of the hone.
Reassemble the cylinder heads using new valve seals.
a mechanical failure causing low cylinder compression.
a fuel leak at the high pressure fuel injection lines or injection nozzles.
a fuel injection nozzle stuck closed. Could be a bad spark plug, plug wire, injector. Also, it could be too tight of clearance between the valve stem and valve guide. I copied and pasted this right from GM's online Service Information:
The vehicle may exhibit a SES Light due to a P0300 and misfire. If the misfire is related to the information below, it will typically happen while cruising uphill, pulling a trailer or on hard acceleration and then stop misfiring shortly after returning to an idle. Typically, cylinders 3,4,5 or 6 will be the ones to experience this.
Remove the valve cover, valve springs and valve seals on the effected cylinder or cylinders. A small wire tie or rubber bands can be placed in the valve stem keeper groove to prevent the valve from falling into the cylinder. Rotate the valve while moving it up and down in the guide to see if it binds. If a binding valve is found, remove both cylinder heads and use either of the following methods to increase the stem to guide clearance:
• Send the head out to a machine shop and advise them to increase the valve stem to guide clearance to 0.002 inch per guide.
• Hone the guide with a 9 mm hone, such as Snap On BCG249, until a clearance of 0.002 inch is obtained. This will usually take about 4 strokes of the hone.
Reassemble the cylinder heads using new valve seals.
#4
10-27-07, 10:23 PM
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Originally Posted by Mr. Dummas
A bad PCM ground will cause this. Check the ground, which is probably located on the front of the passenger side cylinder head. Remove it and clean any rust theat mey be on it, then put it back on. The most likely cause for this DTC is the following:
a mechanical failure causing low cylinder compression.
a fuel leak at the high pressure fuel injection lines or injection nozzles.
a fuel injection nozzle stuck closed. Could be a bad spark plug, plug wire, injector. Also, it could be too tight of clearance between the valve stem and valve guide. I copied and pasted this right from GM's online Service Information:
The vehicle may exhibit a SES Light due to a P0300 and misfire. If the misfire is related to the information below, it will typically happen while cruising uphill, pulling a trailer or on hard acceleration and then stop misfiring shortly after returning to an idle. Typically, cylinders 3,4,5 or 6 will be the ones to experience this.
Remove the valve cover, valve springs and valve seals on the effected cylinder or cylinders. A small wire tie or rubber bands can be placed in the valve stem keeper groove to prevent the valve from falling into the cylinder. Rotate the valve while moving it up and down in the guide to see if it binds. If a binding valve is found, remove both cylinder heads and use either of the following methods to increase the stem to guide clearance:
• Send the head out to a machine shop and advise them to increase the valve stem to guide clearance to 0.002 inch per guide.
• Hone the guide with a 9 mm hone, such as Snap On BCG249, until a clearance of 0.002 inch is obtained. This will usually take about 4 strokes of the hone.
Reassemble the cylinder heads using new valve seals.
a mechanical failure causing low cylinder compression.
a fuel leak at the high pressure fuel injection lines or injection nozzles.
a fuel injection nozzle stuck closed. Could be a bad spark plug, plug wire, injector. Also, it could be too tight of clearance between the valve stem and valve guide. I copied and pasted this right from GM's online Service Information:
The vehicle may exhibit a SES Light due to a P0300 and misfire. If the misfire is related to the information below, it will typically happen while cruising uphill, pulling a trailer or on hard acceleration and then stop misfiring shortly after returning to an idle. Typically, cylinders 3,4,5 or 6 will be the ones to experience this.
Remove the valve cover, valve springs and valve seals on the effected cylinder or cylinders. A small wire tie or rubber bands can be placed in the valve stem keeper groove to prevent the valve from falling into the cylinder. Rotate the valve while moving it up and down in the guide to see if it binds. If a binding valve is found, remove both cylinder heads and use either of the following methods to increase the stem to guide clearance:
• Send the head out to a machine shop and advise them to increase the valve stem to guide clearance to 0.002 inch per guide.
• Hone the guide with a 9 mm hone, such as Snap On BCG249, until a clearance of 0.002 inch is obtained. This will usually take about 4 strokes of the hone.
Reassemble the cylinder heads using new valve seals.
Yah, I would DEFINITELY try the fuel filter first. Very common on these vehicles and WAY less trouble and expense than re-building the cylinder heads. 
You should be able to blow into the inlet side of the filter with little resistance...if not the filter is BAAAAAD......I have replaced many many fuel pumps on these (GM) trucks because the fuel filter was COMPLETELY stopped up and so the pump burned up. It is possible that your pump is already damaged and just so weak that it cannot provide enough fuel when you accelerate, but this is much more rare. I think that a fuel filter is likely to fix your problem.
If not....THEN you can think about taking the cylinder heads off...
#5
10-27-07, 10:27 PM
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