rev up your engines, welcome to a mechanic's Monday, if your car is
hesitating or misfiring, doesn't have very good acceleration you might have a
weak fuel pump, so today I'm gonna show you how to test fuel pump using a fuel
pressure gauge, now in order for a modern fuel-injected car to work right the fuel
pump has to put out just the perfect amount of pressure, so that when the fuel
injector computer pulses the fuel injectors, they spray just the exact
amount of gas, if the pressure is too high, it can run too rich and if the
pressure is too low it can run too lean and not get enough fuel, the most common
thing of a worn-out fuel pump is, the engine will run lean and when the check
engine light comes on it'll say the engines running too lean or you can get
the code for random intermittent misfire cuz if the pressure is too low, the
engine won't be firing right and it's often just a bad fuel pump but
unfortunately unless you have a very late-model fancy car, most vehicles don't
have a sensor for fuel pressure to tell the computer what the actual fuel
pressure is, so it's just left guessing for solutions now some of the modern
ones yeah they have fuel pressure sensors so the computer knows and when
that fuel pressure gets too low it's gonna trip a code for that and you can
figure that out really fast, but if you're amongst the majority of people's
cars, you're gonna have to pressure test the pump to see if it's bad, now years
ago it was real easy you got a gauge and you screwed the
gauge on to a hose and the other end of hose had a threaded adapter that went on
a Schrader valve just like on your tires and that would measure the fuel pressure
but alas most manufacturers don't have Schrader valves for the fuel pressure
gauges anymore, you got a tap into the system to find
that fuel pressure, the manufacturers came up with excuses like, oh well the
Schrader valves had a tendency to leak and that's dangerous leaking gasoline
but really they could make them pretty well and they used to make them pretty
good, it's just a cheaper way to make cars and making it harder for you to
diagnose problems in your car, now if you suspect a fuel pump is getting weak on
your car, the first thing you should always do is, replace the fuel filter
because if the fuel filter is clogged up it's gonna jam up the
passage way, so then the pressure after the filter is going to be lower and the
whole problem could be a clogged fuel filter, so always change your fuel filter
first if it's an easily accessible one like this Toyota that's right in the
front it just bolts on and off, but if you have one of those modern cars where
are those evil swine engineers put the fuel filter on the fuel pump inside the
gas tank and you got to pull the gas tank and in order to change the fuel
filter, then just go directly to a pressure reading of the system because
you never know, maybe the fuel pressure is fine if it is, then you can rule out
the pump and the filter being clogged and even if the filter is clogged you're
gonna pull a gas tank off you might as well change the pump and the filter
while you're in there doing all that work, in the case of this Toyota you need an
adapter to do fuel pressure you can take the top of the fuel filter bolt off, you
go to the fuel filter here's the top of it, you unscrew this bolt and then screw
this adapter on top, then hook up the gauge, then take my advice do all this work on
a cold engine, so if there's any fumes or leaking gas it won't burn on a cold
engine it's safer, then crank it up, the engine won't start cause you got no fuel
going to the engine it's all going to the gauge to see what the pressure is
and in this case the pressure is about 42 psi which is totally normal for this toyota
even though it has 240 thousand miles on it, it still has the original fuel
pump, Toyota uses these Nippon Denso pumps and they're pretty good pumps, now
you can easily look up the pressure readings for your own car on the
internet in two seconds, but here's a warning about really modern cars, if you
notice this gauge only goes up to a hundred psi pressure, if you have a
modern GDI gasoline direct injection, some of those pumps put out twenty nine
hundred pounds per square inch pressure, so let's just say you're not gonna be
testing those pumps yourself, there's just too much pressure, if they have
problems with those systems it's basically you just replace them if it's not
getting any fuel and you don't think that pump is working right, that puts out
twenty nine hundred psi you just buy another pump forget trying to test it,
and since this is mechanic Monday I'm giving away one of these blue driver
fuel pressure tester kits, to have a chance to win, place the clean non
offensive comment on you comments below, and a winner will be
chosen randomly by computers to be able to check their own car's fuel injection
pressure, so if you never want to miss another one of my new car repair videos,
remembering to ring that Bell!