Gapping Plugs

[edwcdc]

Hey Guys, I recently tuned up my 96 tahoe and a friend/mechanic suggested that I gap the plugs at around 56/57 as opposed to the .60 that it should be. Is this a common practice? I have noticed that since I changed my fuel pump it wasn't running that great and my gas mileage was greatly reduced. I decided to tune it up plugs, wires, pcv, air filter, and cap and rotor. This made it run a little better. When the motor is warmed up, it doesn't want to start right away and at least once a week I get a SES P0300 misfire code.

Number 1, should I regap the plugs to the recommended .60 or should I leave them alone?
And number 2, any thoughts on the bad gas mileage and difficulty starting when warm?

Thanks in advance.
Ed

[2000CAYukon]

Originally Posted by edwcdc

Hey Guys, I recently tuned up my 96 tahoe and a friend/mechanic suggested that I gap the plugs at around 56/57 as opposed to the .60 that it should be. Is this a common practice? I have noticed that since I changed my fuel pump it wasn't running that great and my gas mileage was greatly reduced. I decided to tune it up plugs, wires, pcv, air filter, and cap and rotor. This made it run a little better. When the motor is warmed up, it doesn't want to start right away and at least once a week I get a SES P0300 misfire code.

Number 1, should I regap the plugs to the recommended .60 or should I leave them alone?
And number 2, any thoughts on the bad gas mileage and difficulty starting when warm?

Thanks in advance.
Ed

In my opinion, there is not enough difference between .060 and .056 to regap the plugs.

Hard starting when warm and bad fuel mileage sounds more like a bad fuel pressure regulator. The diaphram leaks sucking raw fuel into the intake.

Do a fuel pressure test and watch the pressure after the engine is off. It should hold pressure. I have seen a bad regulator cause the pressure to drop to zero in a few minutes.

Do a search on fuel pressure regulator in the C/K forum and you will see more posts on the subject.

//2000CAYukon

[edwcdc]

Thanks 2000CAYukon. I hear that replacing the fuel pressure regulator is a real pain. I understand from reading on this forum that you have to take the intake manifold off. How difficult is this?
And also, how do you check your fuel pressure? Is there a port or something where you put a guage?

[2000CAYukon]

Originally Posted by edwcdc

Thanks 2000CAYukon. I hear that replacing the fuel pressure regulator is a real pain. I understand from reading on this forum that you have to take the intake manifold off. How difficult is this?
And also, how do you check your fuel pressure? Is there a port or something where you put a guage?

On the Vortec engine there is an upper intake manifold (plastic) and a lower intake manifold. To get at the regulator, you need to take the upper plastic cover off.

There is a test port on the fuel rail where you can hook up a fuel pressure gauge. IIRC, it is on the drivers side fuel line going to the intake. There is a dust cap on the test port that you need to remove to hook up the fuel gauge.

//2000CAYukon

[edwcdc]

Originally Posted by 2000CAYukon

On the Vortec engine there is an upper intake manifold (plastic) and a lower intake manifold. To get at the regulator, you need to take the upper plastic cover off.

There is a test port on the fuel rail where you can hook up a fuel pressure gauge. IIRC, it is on the drivers side fuel line going to the intake. There is a dust cap on the test port that you need to remove to hook up the fuel gauge.

//2000CAYukon

Once again thanks for helping. I will see if one of my friends has a fuel gauge and see if my pressure isn't holding.

Ed

[wafrederick]

GM does have problems with the distibitor gears for the vortec engines and most auto parts stores,dealers stock the distribitor gear.It might be a worn out distribitor gear and it will cause a miss.I went through this and and it was a distribitor gear after finding out replacing the plugs was not the problem.Mark the distribitor before pulling out and the timing is not adjustable.The distribitor is set with a scan tool,+ or _ 0 degrees.Where did you get the plug wires?Cheap plug wires will do it too,ones from AutoZone and Advanced.Cheap parts are not the way to go.

[edwcdc]

Originally Posted by wafrederick

Where did you get the plug wires?Cheap plug wires will do it too,ones from AutoZone and Advanced.Cheap parts are not the way to go.

I did get the wires at Advanced. I still have the old ones. Do you think it's worth it to put the old ones back on? I think they are original. Truck has 155k miles on it. The new wires did seem a little cheap compared to the old ones.
The problem started the day the pump went out. I replaced the pump with one from the dealer. The truck ran great up until then so I thought maybe I did something wrong while installing. Come to find out the plastic fuel lines were bent in half so I dropped the tank again and replaced the lines that go to the pump. I never checked the line at the front of the tank. What is the purpose of that line? Is it a return? I thought the smaller diameter line that connected to the sending unit was the return. Any way I dropped the tank again last weekend and discovered that I was pinching the fuel lines again so I fixed that but I still have the problem.

[wafrederick]

If you want to get a new set of plugwires,Carquest sells high quality plug wires and I have been having very good luck with them and with no comebacks.I know Ac Delco plug wires are expensive and are very good I have been hearing