Question about 1998 GMC Sierra

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I replaced intake manifold gasket which the distributor had to be pulled. Distributor was marked but gas mileage has dropped. How do you set timing on a 98 GMC 1500 with 5.7 350? I don't see timing marks but can't really see much down there.

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Hi, I think the distributor only goes in one way, so no way to get it wrong and no timing adjustment either. That said, the thing does rotate and so you do have to get it where the sparks can reach the terminals inside. You might want to bring #1 to TDC (take the plug out and use a screwdriver to check when it's all the way up) and then take the cap off to make sure the rotor is aligned to the terminal in the dist. It might align with the #1 or the #6, depending on whether #1 is on compression or exhaust stroke. Usually, if #1 and #8 distributor terminals are in front, you're about right.
Other things that can affect mileage are a bad fuel pressure regulator or camshaft position sensor. The latter will usually put the engine light on if it craps out, but the regulator may not. The regulator is on the fuel rail. Pull the vacuum line off the regulator and plug it with a golf tee. Then start the engine and check for gas coming out of the open vacuum port. If it does, replace the regulator. If you have a schrader valve on the fuel rail, check the preesure there with engine running. It shouldn't be more than 65 psi even with the regulator plugged in. It should peak around 60 psi when the throttle is cracked wide open.

Posted on Mar 27, 2011


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2000 chevy s-10 blazer distributor placement

Hi Jerry,

Welcome to the club! Anybody who has never had this same problem has not worked much on cars! I say this because I have done the same thing several times.

Anyway, there are timing marks on the front crankshaft pulley and on the distributor. (see pictures)

You have to be sure that Number 1 piston is coming up on the compression stroke when you line up the mark on the front crank pulley with the indicator on the timing chain cover. To do this, remove the spark plug from #1cylinder and stick your finger in the hole. Have a helper "bump" the starter untill you feel the compression trying to push your finger out of the hole. Then use a wrench or socket on the crankshaft pulley bolts to get the marks lined up correctly.

If you look at the edge of your distributor with the cap removed, you will see two marks on the edge. One is an "8" and the other is a "6". when you drop the distributor into the hole, the distributor rotor needs to point directly at the "6" mark. (Since your Blazer is equipped with a 3.4L 6-Cyl. engine) (See Picture)

Sometimes the oil pump is not lined up properly to let the distributor drop all the way down in the correct position. There are two ways to handle this:

1. you can stick a LONG screwdriver down into the hole and try to rotate the oil pump into the correct position.

2. You can find the spot where the distributor WILL drop all the way down, then lift it back up and move it forward 1 tooth. the oil pump will also move 1 tooth and let the distributor drop again. Repeat this until the distributor drops into the proper position to get it lined up with the mark on the distributor.



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My car is 2004 Chevy Blazer, 4WD 4Dr, 4.3L. I changed intake manifold gasket today. When I pulled off the distributor, I didn't mark the position of the rotor, distributor and lower manifold. I thought...

Turn the engine over and bring #1 piston to the top of the cylinder then remove the dist. cap and be sure the rotor is pointing to #1 plug wire in the firing order. Turn the oil pump shaft with a screwdriver so you can keep the rotor pointing to #1 in the firing order set the dist. You have to pay close attention when you set the dist to the oil pump shaft or you can get it a half tooth off and car will backfire when you start it. Good luck

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My 98 exployer is misfiring on all 6 cycdeers but runs fine after warmed up

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Priority Action Part Type Cause 1 Inspect Wireset Worn, Damaged or Faulty Spark Plug Wire(s). 2 Inspect Distributor Cap Loose, Burned or Cracked Distributor Cap. 3 Inspect Distributor Cap and Rotor Kit Loose, Burned or Cracked Distributor Cap and Rotor. 6 Inspect Spark Plug Fouled, Damaged, Broken, or Incorrectly Gapped Spark Plug(s). 7 Inspect Coil - Ignition Faulty Ignition Coil. 8 Inspect Condenser-Ignition Faulty Condenser-Ignition. 9 Inspect Point Set Burned, Worn or Incorrectly Set Ignition Points. 15 Inspect Timing Specification Incorrect Ignition Timing. 19 Inspect Fuel Injector Dirty or Worn Fuel Injectors. 21 Inspect Intake Manifold Gasket Leaking, Worn, or Damaged Intake Manifold Gasket. 22 Inspect Distributor Worn, Damaged or Faulty Distributor. 24 Inspect Valve Burned, Worn, or Sticking Exhaust Valves.

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answer , very carefully ...

drain coolant , remove and mark all vacuum lines , make a schematic to diagram your hose routing, disconnect and plug all fuel lines, remove distributor and mark location of rotor, disconnect battery, remove any necessary cables, brackets and or accesseries, remove intake mounting bolts, note length of bolts and reference location, pry up on intake , remove intake, scrape old gasket off , must be very clean to reinstall new gasket or you will cause a leak..

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