So, recently here in Ohio is been hot, 85+ degrees. When it's hot the Blazer will stall when at idle, coasting or at a stop light. When it's cool, zero problems.

While messing with the Blazer today trying to replicate the stall, sitting in it with the driver's door open (car was in park idling) I could hear the fuel pump running whereas just a few hour earlier after the car had sat for a few hours it was very hard to hear. While listening to the pump I could hear it getting louder as if it were revving up Its pitch getting higher. It reached a peak, there was a break in the sound and the car stalled instantly and the pump kept running but at a lower pitch.

Now, whether the break in it's noise as the car stalled was the pump causing the car to stall or the stall caused the break in the sound, I do not know. It happens near instantaneously.

I believe the pump is overheating, skipping a beat so-to-speak and the engine stalls. Is my conclusion sound and supported by the data I have or am I grasping at straws? I have added more gas to the tank to test if the added fuel will keep the pump cool. I believe if this test works it will verify that the pump is indeed overheating. Any thoughts?

 

The actual pump motor itself is mounted in a "well" or "reservoir" which is part of the fuel pump module. The return fuel line from the fuel pressure regulator directs fuel into the well which keeps the pump motor fully submerged in fuel whenever the engine is running. At the very least, you'll need a fuel pressure tester to monitor the pressure when the engine stalls, to determine if a loss of pressure is what's causing your problem. Following the instructions in this link may help you narrow the problem down: https://blazerforum.com/forum/2nd-ge...eakdown-88305/

 

Yesterday I did my usual, daily, 20 mile drive (10 there, 10 back) with 1/4 tank of gas. A mile away from my destination it started stalling, on the way home it stalled nearly 20 times. Today I did the same drive, same outdoor temp but this time with over 3/4 tank of gas and had zero problems.

Today it stalled twice while going shopping and once in the drive as I stated in my previous post. Tank was at 1/4. After adding gas, doing my drive I let it idle in the drive for 10 min with no problems. This leads me to believe that the extra 1/2 tank added enough liquid to sufficiently dissipate heat from the pump motor.

Going through the past repair receipts of the previous owner I found that the tank (steel), pump (unknown) and lines (rubber, not plastic or steel) were all replaced in 09'. No info on the parts make/quality.

In order to test the pressure when it stalls I will have to use up the gas I added in order to recreate the initial test conditions. I will order a new pump today and hopefully by Tues afternoon the fuel will be low enough to start stalling again and I can rent a fuel pressure tester. If the pressure is causing the stall then I can replace the pump on Weds when it arrives. If the pump is not the culprit, I can return it with no issues (Amazon Prime). I will also be replacing the fuel filter tomorrow.

Is there also a fuel pressure regulator located somewhere and how would you test it? Since the lines were replaced with 3/8" rubber fuel lines could they be a problem? I saw no kinks in the lines.

 

The link in post #2 explains how to test the fuel delivery system. Both tests must be performed to obtain a 100% accurate reading of regulated fuel pressure, (the link explains why).


Rubber lines: As long as they are "fuel injection rated", the proper type of clamps were used, (not worm gear) and there are no kinks, they are fine and shouldn't present any problems.