2001 Blazer LT 4X4, 120,740 miles. I have replaced the alternator, fuel filter, and battery. It will turn over but it just will not “catch”. Any ideas?? I am a basic mechanic so I can do some things. Should I be looking at the distributor cap, rotor, wires, plugs?? Any ideas or advice would be greatly appreciated.

 

Fuel pump?

 

Almost surely fuel pump or fuel pressure regulator. Check fuel pressure at the rail.... needs to be ~60. Wouldn't hurt to check for spark to be sure.....

 

First thanks for the information, guys. Now for the strange thing. It sat since Friday morning when this all started. It didn’t start. We took off for the weekend in my wife’s car and came back Sunday. Tried again. No luck. Got up this morning and again it wouldn’t start. Then I got thinking did I hear the fuel pump “whine up” as I call it. Well I tried it and sure enough it was, which to me meant at least the pump was doing something. I did it twice. Then just for grins and giggles, I tried to start it. It fired right up!!!!!!!!!!!!!! Have no idea unless my fuel filter was clogged and I broke something loose. So this weekend I am going to replace the fuel filter and run a fuel treatment/injector cleaner through the system. What do you think?? I will keep you guys posted. Again, thanks.

 

Sometimes instead of failing outright the fuel pumps start getting weak, meaning they put out slightly lower psi than they should. If so, sometime the motorwill start, sometime not. Also, cycling the key a couple times may get you over the threshold to start. I'd make sure to test fuel pressure and make sure it isn't going south on you... or you will get stranded somewhere.

 

Do not over look the start of an ignition switch failure as well. Have you noticed the security light on the dash when it was not starting?

 

The security light seems to befunctioning normally. Nothing unusual about it. I assume the ignition is working properly since the engine was turning over every time. I will be making some phone calls today about the fuel pump replacement and keep you guys posted.

 

Ok, it has to be the fuel pump. It did start and ran great for three days. Then the same thing. I did get stranded but it was at work so no foul. I finally got it to turn over so the wife and I went back to my office and I drove it home. Now that it is here, I can search for a fuel filter and if I am lucky have it start just one more time so I can drive it to the shop and not have to have it towed there. Any suggestions on where to look and what a good price would be? Thanks.

 

You mean price for a fuel pump, not filter, right? I didn't check today but IIRC the pumps alone are ~$100 and the entire assembly ~$250. Check Rock Auto, or the usual places Advance Auto or Autozone online.

 

I would only recommend AC Delco fuel pumps. Many have had problems with other aftermarket pumps and if you have to replace it once in short order, it will cost a lot more in time. RockAuto.com has some decent prices. You can also find pumps on eBay for a good price. Run a search, I ran down through the fuel pump part numbers in a few old posts. MU85 comes to mind as far as the AC Delco PN is concerned so you have something to search for.

With that said, you may want to look into a wiring problem or possibly a relay problem (or ignition switch as I suggested earlier). Fuel pumps often aren't a gone one day, working the next kind of thing. A failing ignition switch often has other problems associated with it, but the engine will almost always turn over just fine when they start to go. Most often, the security light illuminates, but it is not always the first indicator. Sometimes the gauges do not respond properly. And definitely one of the symptoms is a non-responsive fuel pump.

I would definitely check to make sure that the fuel pump is getting power properly while you are experiencing the no start issue.