your car running sluggishly? Are you noticing a slight stumble as you drive?
Chances are, your fuel injectors need to be cleaned. In this tech article, I
will go over the easy steps in removing the fuel injectors and cleaning them
out. This article applies to my E30 325is 6 cylinder, however the principles
behind this apply to nearly every car in general. Usually, most people just
run a can of fuel injector cleaner in a full tank of gas. I would also
recommend this, but in cases of cars that have been poorly maintained or
have been sitting for a while, the only way to get those injectors truly
clean is to pull them out.
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said, lets begin. The first step is to disconnect the battery, as we will
be working around fuel injection components and raw fuel. You dont want a
spike going through the system. This could fry your fuel injection computer.
Also, you dont want t a random spark igniting raw fuel. This is VERY bad.
You will have to sit back and watch as your car goes up in flames.
Disconnect the battery and be safe.
the car until you have less than a quarter tank of fuel in there. This will
reduce the overall amount of fuel pressure in the system and help prevent
raw fuel from gushing out when you remove the injectors. Now, start out by
removing the hose clamp holding the fuel line to the fuel pressure regulator
and plug the fuel line using a bolt. Also disconnect the vacuum hose at the
top of the regulator. This picture shows the fuel pressure regulator. Now look at the rear of the engine on the
passenger side right above the valve cover. You will see the connection for
the rear fuel line. Loosen the hose clamp that
holds it to the fuel rail and remove the fuel line. Plug the end of the fuel
line with a bolt. Be prepared for some raw fuel to spill out of the lines.
Just have a rag nearby to clean the fuel up.
Remove the four 10mm bolts that hold the bracket between the valve cover and
the intake manifold. Now take the bracket off and set it aside. We will need
to remove this bracket in order to remove the fuel rail. Now loosen the hose clamp holding the breather hose to
the valve cover and pull the breather hose off and move it out of the way.
now must remove the six electrical connectors for the fuel injectors. Simply
push the metal bar in and pull up on the connectors to remove them. Now,
locate the four 10mm bolts that hold the fuel rail in
place. This picture shows the location near the front of the engine. This picture shows the bolts near the rear.
pull up on the fuel rail evenly from each end. You may have to use a little
force to get the injectors out of the intake manifold. Once out, maneuver
the whole fuel rail from out between the cylinder head and the intake
manifold. Be sure to have a coffee can or some other sort of tray around to
catch the extra fuel inside the fuel rail. Now take the whole fuel rail over
to a workbench or other suitable work area.
will now need to separate the fuel injectors from the fuel rail. Use a small
flathead screwdriver to remove the retaining clips holding the injectors on
and store them in a safe place. Now pull the injectors out of the fuel
rails. You may have to use a little force to get them out. Keep in mind that
you will most likely have a little bit of gas spill out when you remove
them. Once out, remove the old seals on the top and bottom of the injectors
and throw them away. You never want to re-use injector seals. If you do,
there is a chance they may crack. This could cause an air leak or worse,
cause raw fuel to leak out.
the injectors out, you might see a build-up of crud on the tips. This is
usually a mixture of carbon deposits, fuel additives and gas. Use a rag to
wipe off as much as you can. Now, get a can of brake cleaner and spray the
outside of the injectors and the tips. Use a soft brush to remove any grime
on the tips. Now spray a bit of brake cleaner down the inside of each
injector and blow them out with some compressed air. You may be surprised at
what comes out of there. Each fuel injector has a small filter that collects
any debris or crud in the fuel system. Spraying the brake cleaner in there
will dissolve any deposits in there.
good way to clean the inside is to spray cleaner in there, then hit it with
compressed air. Keep doing this until the brake cleaner coming out is clear.
This is an indication that they are clean. CAUTION: be sure to use goggles
when you do this, as the compressed air will spray the cleaner everywhere.
You dont want this stuff to get into your eyes.
you have all the injectors clean, get some new fuel injector seals and place
them on each end of each injector (Pelican Parts carries these seals for $0.61
each. You will need 12 of them) Now to re-install them, put a little engine
oil on the outside of the seals and press them back into the fuel rail. The
engine oil will help you push them into the fuel rail as well as help seal
them. Now re-install the retaining clips the secure the injectors into the
go back to the car and plug each injector port with a small piece of paper
towel. Now take some brake cleaner and a small brush and clean the area
around the injector ports. This will clean the area and prevent any loose
dirt or debris from entering the injector ports. Take the paper towels out
and look inside each port to make sure there is no dirt in there. If there
is, use a small vacuum to suck it out.
each lower injector seal with a small bit of engine oil and position the
fuel rail/ fuel injectors back in place in the intake manifold. Now, using
equal pressure on both ends of the fuel rail, push down until each injector
seats in the manifold. Now re-install the four 10mm bolts that hold the fuel
rail in place.
installed, re-attach the fuel line on the rear of the fuel rail and tighten
the hose clamp that holds it in place. Now move to the front of the rail and
re-attach the fuel line to the fuel pressure regulator and tighten the hose
clamp that holds it in place. Also re-connect the vacuum hose at the top of
the regulator. Now push the electrical connectors for the fuel injectors
back on. Just push them down until they click.
take the valve cover breather hose and push it back onto its fitting on
the valve cover and tighten the hose clamp that holds it on. Next, re-attach
the bracket that holds the intake manifold to the valve cover and install
the four 10mm bolts that hold it in place. Now would be a good time to
change out the fuel filter on the car if you have not already done so.
re-connect the battery and fill the tank up. When you restart the car, it
may take a few times to get it to run. This is normal. Keep in mind that the
fuel system is under constant pressure and we just opened it up, introducing
air into the fuel lines. It will take a little time for the fuel pump to
deliver fuel to the injectors and pump all the air out of the system.
Well, there you have it - it's
really not too difficult at all. If you would like
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