I'm posting this tome "for the archives," hopefully it will help an
owner to fix his or her car.
The engine is a '97 24 valve straight six, #104.995.
I've owned this car since new. After about 15K miles I noticed that some
starts took longer but I couldn't relate those instances to anything. At
18K miles the dealer checked the fuel system pressure and found it to be
OK, they also checked the crank position sensor; it was OK. No other
ideas were offered and the new car warranty expired.
Time passed and the problem ripened. Cold starts were instantaneous, but
with a strong fuel odor from the exhaust. Hot starts were fine if the
engine was restarted within, say 10 minutes, but delayed thereafter -
crank crank crank - until the throttle was opened the engine then roared
to life. The exhaust then had a strong fuel odor. It was as if a
carburated engine were "flooded".
The engine ran well otherwise, had lots of power and good fuel economy;
it passed all California's biannual SMOG inspections.
At 30K miles I installed new spark plugs and found a strong fuel odor in
the engine's air intake and #6 spark plug wet with fuel. I added fuel
system and injector cleaner to the tank and the problem seemed to
improve, but not for long.
Since I know more about carburated engines than fuel injected ones I
researched gas fuel injectors and learned that they can be
professionally cleaned ultrasonically of the fuel deposits that build up
over time but that a leaking injector due to a bit of internal rust or
corrosion probably needs to be replaced. There was also the actual "how
to" aspect of removing the injectors and whether to remove all six for
cleaning and testing or to try to identify the probable leaker.
Rather than pull all the injectors for testing I parked the car for a
few days (to leak) and removed all the spark plugs. Sure enough, #6 was
again wet with fuel so I was assured that #6 injector was the culprit.
A "rail" (pipe) supplies (approx.) 45 psi fuel pressure to the
injectors; the connections are sealed by rubber "O" rings on the
injectors. So to remove the injectors one needs to relieve the fuel
pressure and drain the fuel rail. Some Volvo owners pull the fuel pump
relay and run the engine to reduce the pressure and consume fuel in the
rail. Others just put a rag over it to contain the spray and catch as
much fuel as possible in a can. Neither prospect attracted me.
I had the local M-B dealer estimate the job of replacing only #6 fuel
injector - not cheap but specific, no "let's try this and if it doesn't
work we can do that" guessing game. Now it's fixed - 2 hours labor and a
new Bosch injector.
What a difference! Just like a new car again.
Thomas G. Lambach
'97 E320 @ 38K miles