MrMekanik

hello, new to the forum, I have searched through the threads and have not been able to find any issues that match mine, so, here goes, I have a '99 Blazer LS with the 4.3 Vortec, it starts, runs and drives fine until it gets hot and idles for extended periods, it will still idle fine, but if I press the gas, it bogs out and will die if the gas is held, let off, idles fine, if very slight pressure is applied to the pedal, will very slowly increase in speed, sudden push, bogs out, the fuel pump, fuel filter, injector spider, fuel pressure regulator, spark plugs, wires, distributor cap, rotor, throttle position sensor, idle air control, battery and alternator have been replaced, I am getting no check engine codes. I drive 30 or so miles each way to work, if the traffic does not slow to a crawl on the interstate and I do not have to sit at idle for extended periods this issue does not happen, but when it does happen, it has left me stranded, let it sit overnight, no issues at all till it happens again. I am at a loss. Any help would be greatly appreciated.

jfmorris

Wow - you've for sure fired the parts cannon at this problem!

One thing that comes to mind. You've tried to address any spark or fuel delivery issues. Have you checked the MAF (Mass Air Flow) sensor? It is inline in the air intake. If that misbehaves when the engine is hot, the ECM won't know how much air is coming into the engine, and things could get wonky. Note I am NOT saying to go buy a new MAF - just to check it.

If you can buy or borrow a ODB2 reader that can display or capture live data, you should be able to examine the MAF readings when the engine is cold versus hot, and see if it is not reading correctly when hot, when you step on the gas pedal.

Other than that, a connector or component is obviously acting up when hot. I am hopeful someone else can come along with better ideas than me...

MrMekanik

I have checked and cleaned the MAF, had a scanner on it while driving for a while, but the issue did not happen while I had the scanner on it, most of the parts that have been replaced were replaced due to the truck sat for a couple of years, the fuel system was completly shot when it was dug out and hauled to the shop. All of it was replaced to get it to run correctly, just still has this issue if it idles for a long period or gets too hot, at highway speeds, the temp stays under 210, sitting still at idle, will get up to 215-220, I am going to flush and fill the coolant system when I get the chance, probably gunked up from sitting.