TPI fuel pressure

[Marteney, Steven J.]

Need some help from you guys who have been there, done that...
Was checking fuel pressure with my mechanical gauge.  On my friend's stock
IROC 305, pressure was around 36psi.  Crack the throttle and it would jump
to 43, works good, very smooth and steady gauge reading.

Now, my 89 350, not stock.  Before I checked the IROC I noticed my fuel
pressure was DROPPING when the throttle was cracked.  However, with the
vacuum line unplugged it would go up to 48.  (I have an AFPR.)  Now, after
seeing my friend's IROC I checked it again yesterday.  The gauge reading is
very erratic.  Bounces around fast about 5psi.  I crack the throttle and it
initially goes up, then settles at a LOWER pressure than at idle.  If I
unhook the vacuum, it is still erratic.

So, is the erratic pressure causing my rough idle (potentially) or is the
rough idle causing my erratic pressure?  (Wouldn't think so since vacuum
unplugged does the same thing.)  So, what's bad?  Fuel pump?  Regulator?
Both? Neither?

Any help is appreciated.  Also, am willing to do any tests you think will
help.

Steve
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