Failure Mode From Hell Solved

[russ southerlin <russell.s.southerlin@ast.lmco.com>]

Gentlemen,
The failure mode from hell is finally solved (its been a long 3 weeks)
after replacing almost my entire fuel injection system. After numerous
hours troubleshooting a low fuel pressure problem and subsequent
dismantling of my fuel distributor (which I never got back together -
had to buy a junkyard unit for $130) I discovered, with the help of many
E-mails back and forth from Scott Justasin (thanks Scott) and Phil Payne
(thanks Phil), that the fuel flow rate was too low. I then concluded
that it had to be either a restriction in the fuel line or the new fuel
pump was defective. here is what I found: I am assuming that my Mitchell
manual 0.71 qts. in 30 sec. is spec. 

1) Removed fittings at press. accumulator and ran pump - flow was same
as at fuel dist (very low about 1/2 the 0.071 spec.).

2) Removed fuel pump and did a bench test on FP itself.

3) With press. damper removed and check valve in place pump output was
great - over twice the 0.071 spec. (fuel came out so fast I could not
even get a good measurement).

4) With new check valve and press. damper in place flow was low - 1/2
spec.

5) With old check valve and damper in place flow was great - over twice
spec. (my old check valve won't hold any pressure so using it is out)

6) Upon inspection of the new check valve and damper assy. I noticed the
length of the new check valve (the section that screws into the damper
through the banjo fitting) is about 0.025" longer than the old check
valve. When this is screwed into the damper that extra 0.025" is
bottoming out (or coming very close) against the internals of the damper
causing a flow restriction.

7) To verify this I put an additional (0.050") washer (2 washers total)
on top of the banjo bolt to take up this 0.025" and with new check valve
and damper flow was great. - over twice spec. 

I then put everything back together with an extra 0.030" washer in place
and I have rock solid 92 psi of system pressure.

Car is running great - I think I was having a bad case of 15psi
withdrawal (my 79 F150 4X4 long bed, super cab - read slow pig - doesn't
do a whole lot for my need for speed!!!!!!!!!!!!)

I think I might post some lesson I learned along the way in the near
future.

Russ
87 5KTQ