Well… most of you already know where this is going…

 

Now, I am not normally this stupid. I say STUPID, because I know better!!  So just

what was it that caused me to momentarily lose sanity? Pressure!  Isn’t that what usually

throws our thinking off? Ever notice just how easy things seem when your viewing them

from the confines of a classroom? How the instructor just seems to make it all sound so

easy?

 

Real world for many of us technicians is having 3 jobs going at once, the phone ringing off

the  hook, an empty stomach (can’t find time for lunch), worrying about flagging enough hours

etc… You all know the story…

 

But was that it for me on this job? Nope, not this time. I just cannot explain why my brain

malfunctioned… The good news is the malfunction only lasted for a couple of minutes <g>

If there are any green horns out there reading this, please take some comfort that even those

of us who have many years of  acquired knowledge and experience STILL screw up from

time to time. That is one reason I will never refer to myself as a Master Technician, regardless

if ASE or anyone else wants to call me one. That is just one of my hang-ups…  I never will

feel good enough <g>

 

Ok enough blabbering… on to the story! With approximately 35 psi of fuel pressure in the

fuel rail, the fuel pump power feed disconnected, the engine cranking, and the injectors firing,

the fuel pressure did not drop; and that is how it should have been…

 

Many times I have referred to Poppet Nozzle Injectors assuming everyone knew what I was

talking about; today, lets make sure. Poppet nozzle injectors are composed of three parts.

 

 

The injector itself is a solenoid-operated valve that either allows fuel flow or blocks it. The injector solenoid is operated by the PCM. Take note that the injector itself does not care what the fuel pressure is; it will flow fuel at any pressure PROVIDING the outlet is not blocked.

 

The fuel tube is just that; a plastic tube connecting the injector to the poppet nozzle.

 

 

The poppet nozzle contains a spring loaded ball which will not allow fuel past its tip unless sufficient pressure is achieved to force the ball off of its seat. The pressure required is approximately 42 psi. Now just because

the nozzle will open at that pressure does not mean that the engine will run with that low of fuel pressure! Normal fuel pressure should run between 55 and 62 psi with the engine

running.

 

 

 

Since 1996, the fuel injectors and pressure regulator are serviceable separately. Previous CPI units (that also have poppet nozzles) are only serviced as a complete unit. Remember, this has a vacuum modulated fuel pressure regulator. Key on engine off, you should get 60 to 66 psi. If you have sufficient

Key-On-Engine-Off pressure but while cranking the engine over, the pressure drops below 50 psi, the engine will not start.

 

So what was wrong with my S10? I feel so stupid… The coil wire had come off of the distributor. I would

have found it much sooner if I hadn’t decided to go high tech right out of the gate. I really didn’t spend that

much time fooling around with this and came out quite nicely in the end; the customer spent a great deal

of money on much needed maintenance work. Cap, wires, rotor, tune, decarb, etc… <g> Yep, that’s right.

A high mileage vehicle at a dealer; we see lots of them…

 

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