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2002 chevy trailblazer_ls
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Discussion Starter #1
2002 TB 4.2L. Brand new Bosch fuel pump. Just installed since I had it on the shelf anyway. Not a fun job in the driveway.
New style ignition switch last year replaced.
New fuel filter about 20K miles ago.
New/used fuse box about a year ago.

So the other day the truck would start but then stalled immediately. Tried a few times, some times it would not start and just keep cranking. Every now and then it would start but then stall within a second.

Had it trailered home and did the fuel pump since it sure seemed like the problem and that I already had it on hand. Go to start the truck after checking all of the fuel lines and no start. Just cranks. I'm fairly mechanically inclined but not the greatest with wiring.

I'm not sure where to start but it seems like a fuel problem still. Could a fuel line be clogged? I can't see the filter being clogged so soon or at all. I have noticed that my battery is weak after only 1 year but I had it trickle charged overnight before testing and trying to start it.

Please help with some guidance ladies and gents. :)
 

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2002 chevy trailblazer_ls
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Discussion Starter #2
I should add that I can hear the fuel pump prime when turning the key on.

I just ordered a fuel pressure test gauge from Amazon for $35. Wanted one anyway and no I have not tested the pressure.
 

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Use a LOGIC TREE and don't go looking for zebras when you hear hoof beats.

  1. Listen for an even cranking rhythm
  2. Confirm spark by getting a child to stick their finger --- nevermind.
  3. Confirm injector activity (you said you have fuel pressure - right?) although on a Vortec, this can be complicated.
Very few things can cause this NO-START BUT CRANKS OK problem - but they trickle down to COMPRESSION, SPARK, FUEL, in that order.

Spark & Injection are usually together and if one is working, the other SHOULD too.

Again ---> test them in order - and then go looking for zebas.
 

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I should add that I can hear the fuel pump prime when turning the key on.

I just ordered a fuel pressure test gauge from Amazon for $35. Wanted one anyway and no I have not tested the pressure.
PRESSURE is not the only test --- you need sufficient fuel FLOW too!
 

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2002 chevy trailblazer_ls
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Discussion Starter #5
The cranking was slower than normal. Like a dead battery, charged up but my battery should be fine. This seemed to be normal though for a while and the TB would always start with these conditions.

So it could be compression... I have a compression tester somewhere in my garage, haven't seen it for a while so I may have let someone borrow it.

I'll check for spark tomorrow. How would I test the injectors without bringing them to a service station?

I have a feeling its the fuel flow as you stated last. But it's an 02 so there's no port in the engine bay. I will check the things you stated and report back. Working tomorrow so it'll be tomorrow night. Thank you.
 

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If you have an FI Fuel Pressure & Flow Tester, this would be easy.

I didn't know that there's NO pressure tap on the fuel rail of these Vortecs!

If that's so, then the only place to test the system is at the fuel filter - but I know that the EXTs don't have a fuel filter.... so that's a problem!

I'm also new to TrailBlazers, but have been in the auto repair industry as both owner and operator, so this should be easy.

I'll take a look at my 2005 California CARB Certified TB EXT and see what I can find, but it's night here and I'm kinda sleepy. Tomorrow calls!
 

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2002 chevy trailblazer_ls
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Discussion Starter #7
Okay so my battery is less than a year old but it seemed weak so I replaced that. Before I started it up I already had the coils and plugs out so I cleaned the TB while I was in there.
The TB was really gummed up. It makes sense since I had a bad oil leak and was too broke to buy the parts and a few special tools to fix it. So I had to deal with it for about 2 months.

Between the TB cleaning and a new battery the truck started just fine. All good now.

However, if my battery is dead this fast then I likely have a electrical issue still. I've replaced a bit of the harness and have been through 2 fuse boxes. What else in the electrical could cause my battery to drain?
 

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Okay so my battery is less than a year old but it seemed weak so I replaced that. Before I started it up I already had the coils and plugs out so I cleaned the TB while I was in there.
The TB was really gummed up. It makes sense since I had a bad oil leak and was too broke to buy the parts and a few special tools to fix it. So I had to deal with it for about 2 months.

Between the TB cleaning and a new battery the truck started just fine. All good now.

However, if my battery is dead this fast then I likely have a electrical issue still. I've replaced a bit of the harness and have been through 2 fuse boxes. What else in the electrical could cause my battery to drain?
How long does it take to 'kill' the battery?

If less than a few hours - there's gonna be HEAT somewhere..... find something that's still hot - or getting hotter.

Use your nose and sniff for things that are smoking or really hot.

If it takes overnight - then you have a device somewhere that is draining the battery and can handle it pretty well. It may not get noticeably hot - but if you use a thermo-scan infra-red thermometer, you can find it pretty easily.

How about any add-on boom boxes, amplifiers or remote engine start devices?

At this point - I got little to add - but you are there and I am here and I need more input!
 

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2002 chevy trailblazer_lt_ext
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For the love of god, dump this place and get some real help! We have tons of info and real people, not actors. We have FAQ's that lists most of the common problems like yours:
Cranks but won't start

@Ravalli Surfer , Sniff for a battery drain? Check for heat? Really? And EXT's do have fuel filters. In fact, all of them have filters from 02 to 04. 05+, all of them, are in the tank with the fuel pump. Design change from a return to returnless system. You can check for fuel pressure at the fuel rail on the 05+ instead of at the filter on the older ones, which is actually easier.
 

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2003 gmc envoy_sle
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For the love of god, dump this place and get some real help! We have tons of info and real people, not actors. We have FAQ's that lists most of the common problems like yours:
Cranks but won't start

@Ravalli Surfer , Sniff for a battery drain? Check for heat? Really? And EXT's do have fuel filters. In fact, all of them have filters from 02 to 04. 05+, all of them, are in the tank with the fuel pump. Design change from a return to returnless system. You can check for fuel pressure at the fuel rail on the 05+ instead of at the filter on the older ones, which is actually easier.
Take your negativity back to your own forum. Do you really think everybody has stumbled across it, and knew it even existed. You need to make 414 posts here before I ran across your existence.
Just to let you know, the height of your ego just came crashing down to the level of your social IQ. I'm afraid it didn't survive the fall.
I don't care if you have ALL the answers. I prefer not to hear them from you.
And yes, with so much of the newer cars depending on electronics, connectors, and wiring, old school says where there's a stink, there's a possible short. It helped me find out that my fancy new electronic water heater was about to burn my house down.
 
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