Fuel Pressure Fiasco, (Rant)

[Jimmy Lewis]

As many of you may know, I am having fueling issues with my car. Welll...

After talking to some guy at Autozone about a fuel pressure tester, I went in and what commenced nearly drove me to break things, haha. First, I waited in line to get up to the counter to ask about the tester. The guy at the register was obviously the person I talked to on the phone because the other guy had a strong spanish accent and the other looked like a 12 year old. I asked the guy "Do you have the gauge I called about?", all he said was, "isle 5." Not too bothered, I can find it myself, I thought. Well, I walked down the isle and there were nothing but blinged out 9" tachs and other instrument panel gauges. The guy obviously knew what I needed because I talked to him on the phone about it for 5 minutes. I waited in line again and said that I needed a gauge that could be made "in-line" to check the pressure, a simple t-fitting with a gauge attached. He glared at me, and said "isle 3. Fairly bothered at that point, I walk down the isle and all they have is tire gauges and various sockets and such. Getting pretty pissed, I walked up and I say "I know you are allowed to leave behind the counter and actually show me where the shit is." He glares and asks me again what I need, as if I hadn't told him 4 times previously. Well, he simply turns around and hands me a gauge, which looked to be exactly what I wanted. I looked at it and it looked right, but only read to 15psi, and having read that our cars should produce somewhere between 40-43ish psi, something was wrong. I said well my car is supposed to actually put out about 42psi, and he laughed at me and said that I was illinformed. He asked what kind of car it was and I said "an old '91 BMW", he laughed and said that again there is no way that that car should put out 42 psi. I went and placed the gauge on the counter and said that, "I won't be coming back here again."

Just to make sure that I'm not the dumbass, I randomly looked up what the fuel pressure should be on a 5.0L mustang, sure enough, 40psi. Am, I retarded or is this guy? Every fuel pressure gauge I have ever seen reads from 0-100psi or 0-70psi. I do know that older carburated motors probably put out less pressure than the newer injected cars, but still, the guy should know that a '91 BMW isn't going to be carbed.

End rant. Input?

[strad]

A 15 PSI gauge might work fine on a carbureted motor.  I seem to remember that our 86 Suburban mechanical fuel pump (350 4bbl) ran at something like 12 psi.  Don't quote me though because it's been 20 years or so since I thought about it.  

The M42 fpr is rated at I think 3 bar, which is about 43.5 psi.  Don't ever expect parts guys to know what they're talking about: I learned long ago that most of them do not.  That's why I shop online whenever possible.

[Jimmy Lewis]

Yeah I tried to be as patient a possible and not to sound pompous when I thought that he was wrong. At the place I usually go, the guy wouldn't have even asked what the car was, he would have just asked if it was in the parking lot, and to show the issue I am having to him.  I called him and he said that he had one for $40, which is just fine, it isn't made of plastic and the guy ringing it up won't be deaf and dumb. I guess I'll have to wait until tomorrow to see if my pump is indeed the culprit.

Also, I saw where guys were talking about replacing the pump with a walbro unit? Where can I find an aftermarket pump that will fit like oem? If I can get a walbro pump for under $100, it beats the $230 for the oem bosch. I know this motor isn't going to last another 100K, so I'm not too worried about it. I need it fixed, and soon.

[colin86325]

Unless you've got a parts man who knows what's up, and is familiar with BMWs, always expect the worst.  I mean, you can go to the BMW dealer and also have ill-informed people who only know the modern cars.

This will not be your only such experience, so come to expect it, and be pleasantly surprised when somebody actually knows what the hell is going on.  At least that's my attitude.

[peerless]

Auto Zone, Kragen, Checkers, any big name brand auto parts store = McDonalds.

Do you expect anyone at McDonalds to know their ass from a hole in the ground?

What you needed was a 'fuel injection pressure tester'. They go up to 100psi, and cost about $40 for a basic setup.

[Jimmy Lewis]

I know what I needed and I thought the guy at the counter also knew what I needed, oh well. While I was leaving I saw him go meet a friend of his in the parking lot who was driving a mid 90s Cadillac with what looked like 22" chrome wheels, I guess I expected too much. But am I correct in thinking that a pressure tester hooked up before the fuel filter will measure the true fuel pressure produced by the pump, something around 42psi? I've been such a lazy bastard lately, I still haven't brought Dave (Wise Old Dog) his clutch alignment tool, but I'm on it I promise, haha I'll give you boys a ring sometime this week to go drop it back off. Thanks guys for leveling me out.