Re: [DML] DMC How are the fuel injector suppose to work in this system?

[Soma576@xxxx]

Hello Louis,

having water in the gas for 10 years is probably the worst thing i can think 
of to have to deal with as far as the fuel system goes. this is so stupid 
because if there's water in it, all you have to do is siphon the tank, clean 
it out, put fresh gas in and add that water break-up stuff, and you should be 
ok. why anyone would just let the car sit is beyond me..... but anyway.
let's see if i can help....

In a message dated 10/30/01 6:09:44 PM Central Standard Time, 
jugeauj@xxxx writes:
> I was lead to believe that with the airflow sensor completely closed (as in
> the case with the engine not running) no fuel should make it's way to the
> injectors. Is this true?

this is true. as far as the '2 drops per second' rule, that's what the 
average injector will leak into the cylinders with the plate closed. however 
this is for the average worn injector. if you have brand new injectors 
(which is a MUST with rusty fuel parts!!), they should not leak at all. if 
you haven't replaced them, do it now.

> Is the distributor supposed to allow raw fuel into the intake or is there a
> problem stemming from either of the following:
> 1) Central fuel plunger valve (sorry, don't know the correct name for it)
> in the fuel distributor is bad?

i think the name for it is the fuel distributer regulator pin, but it doesn't 
matter. this could be a problem if you haven't had the fuel distributer 
cleaned by a pro or just replaced it. you see, the pin fits into the 
distributer so well that when you try to pull it out, it creates vacuum 
inside the orifice. that's how well-machined the distributer is. the pin 
and distributer are a matched pair at the factory - you cannot buy a new pin. 
if it is chipped or corroded, you need a new distributer - $1000 new. 
(gulp). it's possible that the pin has been corroded by rust and it's now 
leaking your fuel to the injectors when it shouldn't be. this isn't too 
tough to verify - just time consuming. if you haven't done it yet, remove 
all the lines from your fuel distributer and unscrew the top three screws 
which secure it to the air meter housing. CAREFULLY lift it off the housing 
- the pin just rests in there and you aren't careful it will slip out and 
fall down into your engine bay or something. then you're pretty much screwed 
because if the pin even gets scratched or takes a tiny chip, it's probably 
done for. take the dist off the housing and inspect the pin. look into all 
the holes that go into the distributer and look for wear or rust. carefully 
remove the primary pressure regulator and check that for wear and rust. you 
may have a damaged distributer.


> 2) The 12V battery I used couldn't work the pump up to around 65psi thereby
> not charging the system with enough fuel pressure for the plunger and other
> associated components to function properly?

i would advise against doing this. you will destroy the pump if you run it 
without sucking gas for even a second. the gas is the lubrication for the 
pump! i have done it myself by jumping it with a battery to see if my old 
one worked it not. it didn't after that! also, the sparks from the jumper 
cables could blow up the pump with all the vapors in there! Bosch told me 
that the fuel pump is capable of producing around 7 bar of fuel pressure, but 
a lot of that gets returned to the tank. you can only test fuel pressure 
with a K-Jetronic fuel pressure tester between the distributer and control 
pressure regulator as described in the shop manual. your system pressure 
(primary) should lie around 4.8-5.4 bar.

3) Fuel filter was significantly plugged up to restrict fuel flow thereby

> 

this is easily diagnosed - just replace it, if you haven't already!

water in the gas for a long period of time is the worst thing that can happen 
to your fuel system. you seriously must replace EVERYTHING if in doubt. if 
you have found rust in your banjo fittings, your injectors, or in the main 
metal fuel lines, you have to replace stuff. that includes - draining and 
cleaning fuel tank, replacing fuel accumulator, fuel filter, distributer, 
CPR, cold start valve, injectors, fuel pump, and probably every fitting in 
there too. VERY $$$. when working on the fuel system, you better buy a 
K-Jetronic fuel injection pressure tester. i recommend buying one from 
Tool-Aid.com. only $89 including both primary and control pressure readings, 
all the fittings needed, instructions, and a durable plastic case. sweet 
deal!

good luck,
Andy 


Soma576@xxxx
1982 DeLorean DMC-12 VIN#11596
Fargo, ND 58102


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