Fuel pressure issue - 95 Astro - please help

On Sat, 12 Feb 2005 00:31:13 GMT, aarcuda69062
> wrote:

>In article >,
> Lawrence Glickman > wrote:
>
>
>> > All of these parts are new or re-built.
>>
>> So what is left over that could be causing his symptom of loss of ALL
>> fuel pressure on occasion?
>
>It could be any of the parts he's already replaced.
>The fuel pressure bleeding off at rest can only occur in three
>places;
>1) Injector (CPI) assembly
>2) Fuel pump check valve
>3) External fuel line between #s 1 and 2
>
>It's not hard to isolate sections of the fuel system to determine
>where the leak off is.
>
>> What would you want to look at next as a probable cause of his
>> difficulties?
>
>If it is fuel starvation or over fueling, it will show up on the
>O2 sensor voltage and/or the fuel trim numbers viewed on a scan
>tool, I mentioned this to him in a post a while back at the
>beginning. He procured a scan tool but went no further with it.
>He could have posted the scan data here and myself and a number
>of others could have given out opinions of what was there.

OK. Myself, I've recorded what should be "normal" numbers for my own
engine using a data logger and storing the file(s) on my hard drive
for future reference.

I've also used my Scantool to record what parameters that reveals:
e.g.
long term fuel trim bank 1 % = 5.5, 4.7, 1.6, 2.3
short term fuel trim bank 1 %= 0.00, -2.3, 1.63, 3.9

long term fuel trim bank 2 %= 3.1, 3.9, 7.0, 7.8, 7.0, 7.8, 3.9
short term fuel trim bank 2 %= 2.3, 2.1, 0, -.08, -2.3, -3.1

and I am lead to believe, from my readings, that it is perfectly
NORMAL on my engine for bank 1 to be quite different from bank 2,
although I can't put my finger on the source of that information at
this moment.

Now goody for me, I can program my data logger to record all of the
above values in a continuous stream if so desired, so if I see any
MARKED deviation from my baseline reading, I've got a "clue."

There are many many other parameters I've recorded for baseline
purposes, too many to list here. Point is, I would have reference
values to consult. Maybe this is asking too much for anybody to do.

>He did mention in one post that his running fuel pressure dropped
>to 50 psi, this is 4 psi below the absolute minimum required to
>open the poppet nozzles in his CPI system ( pressure
>differential)
>
>He'd be best off with a scan tool with recording capability, that
>way he can trigger a recording on a test drive at the moment the
>problem occurs, and then review the movie from the trigger point
>for anything unusual.

Wouldn't he get what's called Freeze Frame? IOW, my data logger has
the ability to show all engine parameters it is capable of reading at
the moment a malfunction occurs. I've never had the pleasure of
seeing this happen, so I can't be more specific, IOW, I can't give you
the parameters delivered because it hasn't happened to me =yet=. But
if and when it does, I may post for General Information purposes.

>It's also entirely possible that it isn't a fuel problem.

Could be electrical. Intermittent loss of power to fuel pump, etc.
But I'm wondering if that wouldn't throw a DTC. Again, I've never
experienced ( on this car ) a malfunction so I can't be more specific.

Lg