Hi y'all. So I've got a 98 Tahoe 4x4 5.7. Trucks died on me while driving. Its done it a couple of times before but always started back up. Not this time. The truck isnt getting a spark. Its cranking but not starting. So a buddy helped out and we changed the plugs, wires, ignition coil, fuel filter and crankshaft sensor. We checking and the ignition control module has power. And the distributor and rotor appear to be fine without damage. What's my problem and where do I look next?
I need sone help on a 98 Tahoe......
- Thread starter CWB2316
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Welcome to the forum.
Why change all that without changing the well known problem area of the cap and rotor?
Just for giggles, did you actually check for fuel pressure or did you assume the fuel pressure is there because you said you have no spark? Again, just curious.
Why change all that without changing the well known problem area of the cap and rotor?
Just for giggles, did you actually check for fuel pressure or did you assume the fuel pressure is there because you said you have no spark? Again, just curious.
I didn't change it just because it seemed good from the looks of it.
As for the pressure, no I didn't even check it. I figured that since there was no spark that it wouldn't be an issue to check. I'm not too mechanically savvy. But here's a dumb question. Is it known to not start if I dine see a spark but the pressure is low or off?
You need spark, fuel, compression and air to start the engine.
bsamole
Member
Has the camshaft sensor been checked?
No I haven't checked that sensor at all.
Like @bsamole said, replace that cam sensor. I would always do the cam and crank sensors in pairs. Just like I would always do the plug wires and cap/rotor at same time.
Mean_Green
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This thread is kind of spooking me.
I agree with all the above. Cam position sensors were known to go bad on those trucks. Also, the cap and rotors have had their ups and downs over the years for reliability. My guess is when you remove it you're going to find evidence of electrical tracking to ground (look for fuzz on the metal parts, off colored areas, etc.) Like @OR VietVet said, go after those 2 items and then check fuel pressure.
You could try unplugging the cam sensor and see if it fires since you have a new crank sensor. Some of the older vehicles would allow for a base map run (think safe mode) if certain sensors were unplugged. It may work, but I don't remember exactly what the outcome was for that one.
You could try unplugging the cam sensor and see if it fires since you have a new crank sensor. Some of the older vehicles would allow for a base map run (think safe mode) if certain sensors were unplugged. It may work, but I don't remember exactly what the outcome was for that one.
iamdub
Full Access Member
Check engine light on? Why not plug a half-decent scan tool to it and read the live data? I don't know exactly what data the crank, cam and other sensors would be reporting while cranking, but it'd be something. A quick Google would tell you what to look for.
drakon543
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cam sensor as stated above is a potential and you mentioned the icm is getting power. just because the icm is getting power doesn't mean its doing anything with it. right after i sold my 97 had to diagnose a faulty icm for its new owner and ive replaced 1 or 2 others for people. if it appears to be original id be suspicious of it but there's an actual test procedure for that but i dont recall what it was. when you replaced the cap and rotor was there any wierd residue inside the distributor? ive never tested this theory but with as much trouble i had with distributors and venting moisture it always seemed like the cam sensor was getting hit with an arc and cooking. well that and numerous other dizzy related wtf issues.
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Welcome to the Forum from NH.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
You are already receiving sage advice from the knowledgeable folks on this Forum.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
You are already receiving sage advice from the knowledgeable folks on this Forum.
Where are you checking for spark? If you're checking at the coil wire you are eliminating cap and rotor. These trucks are much more known for lack of fuel pressure. Changing parts without diagnosis usually leads to multiplying problems especially in todays world of new parts being junk.
The minimum required tools for these trucks diagnostics are-
A fuel pressure gauge with a long hose to reach windshield (test drives).
An inline spark tester
A VOM
A cheap bluetooth scanner
Thats less than $100. Easily saved first run to parts store for wrong part, as you noticed.
Here are a few things that may help.
www.tahoeyukonforum.com
A fuel pressure gauge with a long hose to reach windshield (test drives).
An inline spark tester
A VOM
A cheap bluetooth scanner
Thats less than $100. Easily saved first run to parts store for wrong part, as you noticed.
Here are a few things that may help.
Helpful Links
Helpful links- If this is a successful post maybe it could be stickied! Here's the first- https://www.gmt400.com/threads/88-95-service-manuals.43575/ https://67-72chevytrucks.com/vboard/showthread.php?t=700011
www.tahoeyukonforum.com
