Last night, got out of work and2000 Blazerwouldn't start. Crank, crank, crank, no fire. Towed to Firestone repair shop, they say the fuel pump is shot and that I need a tune up because it is missing on cylinder 2. They want $485 to do the tune up, which I can do myself this weekend, but they are refusing to do the pump without the tune up since they say that the missing on cylinder 2 will ruin the new pump. I have a friend who has been a mechanic for several years, and he laughed at this, so I had it towed down the road to a shop that said they would do the pump without the tuneup, but they couldn't sayif the misfiring would affect the pump. I think it is BS, but I'd love to hear other opinions. Also, I've only had the vehicle a couple years and never done a tune up on it (done several on 90's Jeeps and old Bronco), are there any tricks or issues I should know about???

Thanks in advance for the help, I love this site!

 

Completely false. The fuel pump's only job is to supply fuel to the engine. There is no way that a misfire condition in the engine could cause a fuel pump to go bad.

Now, as far as your problem, without a fuel pressure test, I cannot say for sure if your pump is bad. If two places diagnosed it as a faulty pump, then it is probably a bad pump, but I wouldn't condemn the pump until the pressure has been tested, including a leak down test. The SCFI fuel pressure regulators are not as problematic as the earlier CPI regulators, but they still can fail. If the pressure leaks down to zero after the system has been pressurized and turned off, then it is a good possibility that the FPR is shot.

 

a miss fire will give u bad fuel milage thats about all it does to affect the fuel