Hi. New to the forum, but have a repair question.

[sancho]

Hello, I have a 98 GMC 1500 5.0 liter. Automatic.

I've been having an issue with cranking. Sometimes it would sometimes it wouldn't. Once, it wouldn't crank on a Friday and I tried several times throughout and a couple times on the weekend. It woudl just turn over and over but never fire. Well, I was going to trying to gtdet it hauled someplace on the following Monday. I went out, and it cranked right up and ran perfect. It's been acting like that for a few weeks now. Well, I check the fuel pump pressure and it's right at 60. I even poured some gas into directly and nothing. It will turn over but no fire. So, I checked for fire at gthe spark plug. It was firing but it looked a little red and not blue. I put a new coil on it. Nothing. So, I put a new crank case sensor on it. Nothing. I changed the plugs, wires, and cap and rotor all about a year ago and I figured that if any one of them were bad now that it would at least fire but run bad.

I don't know what to do, but I just can't keep changing parts out and I really don't have enough dough to come up with at once to take it someplace.

Please help if you can. Thanks

By the way, I unplugged the negative on the battery so that the computer could reset it's too. I let it sit for 30 minutes. Nothing.

[pearsont74]

if its turning and turning...but never fires, sounds like ignition to me have you checked plugs recently?
the intermittant thing is strange though

[sancho]

yeah, I've check that and I've checked all the fuses.

[1500cheyenne96]

Kinda sounds to me like the coil is bad i've had similar problems with mine(96) is it the original coil still? if it is it will be riveted in if not i would one of the days it's not firing pull a plug and check for spark should be a real nice bright blue if its not i'd say replace the coil. Also it wouldn't hurt to pull the cap and check the cap and rotor for corrosion as that could also be part of the problem.

[Faxcion]

Do you have a bunch of stuff on a single keychain thats heavy?
Beleave it or not the weight of my keys fouled up my ignition one time and it did exactly that.

[Crmzendrgone]

Could be your ICM ignition control module is going bad. I am curious if you follow these steps when you did your cap and rotor a year ago?

You cannot adjust the ignition timing. You may need to adjust the distributor in order to prevent crossfire
. To insure proper alignment of the distributor, perform the following:

1. With the ignition OFF, connect the scan tool.
2. Start the engine. Allow the engine to idle until the engine reaches the normal operating temperature.

Important: The Cam Retard Offset reading will not be accurate below 1,000 RPM.
3. Increase the engine speed to 1,000 RPM while performing the following steps.
4. Use the scan tool in order to monitor the Cam Retard Offset.
5. If the Cam Retard indicates a value of 0 degrees, the distributor is properly adjusted.
6. If the Cam Retard does not indicate 0 degrees, the distributor must be adjusted.

Adjustment Procedure

1. With the engine OFF, slightly loosen the distributor hold down bolt.

Important: The Cam Retard Offset reading will not be accurate below 1,000 RPM.

2. Start the engine and raise the engine speed to 1,000 RPM.
3. Use the scan tool in order to monitor the Cam Retard Offset.
4. Rotate the distributor as follows:
• To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
• To compensate for a positive reading, rotate the distributor in the clockwise direction.
5. Repeat step 4 until 0 degrees is obtained.
6. Turn OFF the ignition.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
7. Tighten the distributor hold-down bolt.

Tighten
Tighten the bolt to 3 N·m (25 lb ft).
8. Start the engine.
9. Raise the engine speed to 1,000 RPM and view the Camshaft Retard Offset.

[Wyley87]

all lights on guage cluster come on? if not could be ignition switch

[gmctrucks]

Have you checked to see if theirs any codes are in the computer? Also where are you from what state?
Good luck! GMC

[hotrodpc]

My guesses would be Ignition Module first, then Coil.