Hi. I have a question and any advice would be appreciated. I have a 95 Blazer, and I replaced the fuel pump maybe 6 months ago. I'm not an experienced mechanic, but I know some, and was able to do the job myself. Well, roughly a month ago, the pump started making a high pitched whining sound when running. Louder than usual. Today while driving, the vehicle died on me. After a few seconds it started back up and I got home okay. In the driveway, with it running (and still making high pitched whine sound) I decided to pull the fuel pump relay. It was pretty hot in my hand I noticed. The vehicle kept running, but I noticed the pitch of the whining dropped a little with the relay out (but still had louder than normal whine) When I put it back in, the pitch went up. I also killed the engine, and with the relay out, I was able to start the vehicle. Now first, I thought it shouldn't be able to start without the relay. But, it did. Second, I was wondering if the relay might be bad (since it was pretty hot, and taking it out affected the loud whine of the fuel pump.) If anyone has a comment or advice, that would be great. Thanks.

 

Not sure how thats possible with the relay out that the pump still worked. However before my fuel pump went out it did the same thing. High pitched whine. Higher than normal then that usual chevy fuel pump whine. Did you replace it with an OE fuel pump? Also start with fuel pressure readings. That could tell you a lot

 

The fuel pump is also powered through the oil pressure switch when the engine is running. I'm guessing that the additional current allowed to the pump through the relay was what caused the pump to make more noise. And if that is the case, the pump is likely on its way out.

What brand of pump did you install? Aftermarket pumps aren't known for their reliability.

 

I agree the pump is probably going south. Since its possibly failing it is probably pulling high amps. Pulling the relay would have removed one of the power sources. I also agree that the truck should have started without the relay. I believe it is actually only supposed to run the pump a few seconds on start up and a fewe seconds after shut down. All other times the oil pressure switch powers the pump.

 

Thanks for the replies. Yes, I am assuming the worse that the pump is going out, after only 6 months. I bought it from Autozone, Airtex, $80.00. After I posted this I read somewhere online that with the relay out, it was able to start because of pressure still in the fuel line. I don't know...maybe. This morning I drove it, and no whine, so it seems like it does it when it's hot out. I guess I'll rent a fuel pressure gauge and see what it says. Thanks.