Kingman Posted August 11, 2011 Share Posted August 11, 2011 I'm working on a 2000 Blazer 4.3L Vortec for my friend's Grandma. It's running like @!*% and dying out due to lack of fuel. Here's the issue, the fuel pump is running and pumping as it should, it's got spark, and when it's cool it runs perfect. Once it warms up for a few minutes it starts losing power and bogging out if you give it too much gas. Eventually it'll die and not restart for quite a while, then it'll start up fine and run for a bit. Repeat the process as many times as you want lol. It backfires out the intake and does what VGs do with the MAF unplugged. I've heard of the CFI issues with the cracked plastic lines inside the intake manifold. I think that's the issue but the parts to fix it are around $400. I made a video of what it's doing... but I was too late and all it did was basically die. No cool flame backfiring. Anyone on here good with Chevrolets? I really want someone to tell me that this injection thing isn't the problem and it's a simple fix. Ideally. But I know how vehicles work... any help would be appreciated! I want to get this fixed for her so she can take care of the 5 grand children living with her. Thanks guys. [media]http://www.youtube.com/watch?v=pURYsk7qn8o[/media] Link to comment Share on other sites More sharing options...
Towncivilian Posted August 11, 2011 Share Posted August 11, 2011 I believe you will have better luck posting on Bob Is The Oil Guy, it's a much more heavily trafficked forum with many knowledgeable members. Link to comment Share on other sites More sharing options...
Kingman Posted August 11, 2011 Author Share Posted August 11, 2011 Yeah I will. You never know where you'll find someone that knows something though. Link to comment Share on other sites More sharing options...
KovemaN Posted August 11, 2011 Share Posted August 11, 2011 That sounds like the CPI/spider issue. If she wants to keep the truck it's worth the rebuild. You will probably want to check the cat since it's probably been dumping fuel. The cat will likely be clogged or melted. Link to comment Share on other sites More sharing options...
BoneZ Posted August 11, 2011 Share Posted August 11, 2011 That sounds like the CPI/spider issue. If she wants to keep the truck it's worth the rebuild. You will probably want to check the cat since it's probably been dumping fuel. The cat will likely be clogged or melted. I agree with this, It is a classic problem with that style 4.3L Link to comment Share on other sites More sharing options...
Kingman Posted August 11, 2011 Author Share Posted August 11, 2011 Damn... Link to comment Share on other sites More sharing options...
adamzan Posted August 11, 2011 Share Posted August 11, 2011 A friend had a similar problem on his gmc truck turns out the fuel pump was worn out and when it would get warm it would not deliver enough pressure. The way he found out was attaching a pressure gauge with long hoses so he could drive and watch it and as it got warm the pressure dropped off. Link to comment Share on other sites More sharing options...
nunya Posted August 11, 2011 Share Posted August 11, 2011 start with keeping a pressure gauge hooked up. Just because the pump is running don't mean its pushing enough. Pump could be weak and once it gets warm losing its power. I don't see the spider rail issue too much with the obdII 4.3Ls but don't rule it out. Any engine light on? Link to comment Share on other sites More sharing options...
BowTied Posted August 12, 2011 Share Posted August 12, 2011 (edited) My 99 got to 270k km without having this issue, so I may not be a lot of help. These engines do require a lot of fuel pressure to run properly. The fact that it runs well cold seems to make me think it is not a fuel pump/pressure thing (it starts right up without trouble cold, right?). It is acting like there is a sensor problem when it comes out of open loop mode. Anyone else think this? Fuel pumps are not particularily cheap. Are there any CEL codes? Edited August 12, 2011 by BowTied Link to comment Share on other sites More sharing options...
adamzan Posted August 12, 2011 Share Posted August 12, 2011 Maybe coolant temp sensor, my friends vw would do that. Run great till it started getting warm then it went WTF OMG BBQ and wouldn't go and then stalled till it got cold. Link to comment Share on other sites More sharing options...
KovemaN Posted August 12, 2011 Share Posted August 12, 2011 I don't see the spider rail issue too much with the obdII 4.3Ls but don't rule it out. I didn't really look into how the 4.3 changed over the years, but the one I had a problem with was a '96 with OBDII. It was a GMC S-15 Sonoma. The problem started out innocently enough, the cat got clogged on a long road trip so I had a shop hollow it out and all was good. Eventually the truck started having more and more problems with stalling/warm starts. There was always a strong fuel smell, but I attributed that to the missing cat. I finally determined that the CPI crap was leaking. Good news though. Since then, a number of companies have released a MFI conversion and RockAuto has it for $140. You will also need to buy the adapter bracket for $20 and then all the related gaskets. You should be able to rebuild it for under $200. Of course it would be a good idea to check the fuel pressure first. Link to comment Share on other sites More sharing options...
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