The Resurrection of Vixen Continues...

["Stragand, Dave" <dave.stragand@xxxx>]

Hi All,

I've made a bit of headway with my idling problem. Berryman's ChemTool
B-12 has helped to smooth things out a bit, as well as replacing the
o-ring seal under the fuel distributor and adjusting the idle mixture.

I've got a new problem though now, of course. It seems that once the
car has been idling/running for about 2-3 hours, any attempt at
acceleration is met with at best a "bogging" condition, and at worst, a
stall. This has happened every time I have ran the car for a while in
the last few weeks. Now with the luxury of a fuel pressure gauge, I can
see that when this situation occurs, the following conditions are true:

- The fuel pressure (not control pressure, but system pressure) dips to
between 3 and 3.5 bar, and fluctuates heavily. (Test done with pump
jumpered at RPM relay, engine off)
- Control pressure remains at around 3.5 bar, with slight fluctuation.
- Rest pressure starts at 3 bar, dropping to around 2 bar in 2 minutes,
and sinks to zero in about 30 seconds thereafter.
- Car will restart easily, but dies after a few seconds.
- Fuel temperature is very warm.

It would help to have a comparison, eh? 'Nuff said. With the engine
running for only 5-10 minutes (warmed up from a cold start), I can turn
it off and find the following:

- The fuel pressure (not control pressure, but system pressure) steady
at 4.9 bar. (Test done with pump jumpered at RPM relay, engine off)
- Control pressure remains steady at around 3.5 bar.
- Rest pressure stays above 3 bar for about 15 minutes or longer.
- Car will restart easily and stay running.
- Fuel cold.

I believe the warmed-up from cold start figures all fall within specs.
(By the way, I installed a spring in the suction tube last week, so I
can rule out the tube collapsing when warm).

With these facts in mind, I'm leaning away from a leaky injector (rest
pressure would drop faster initially then slower later, right?), and a
bad accumulator (rest pressure is great when cold). According to my
figurin', that leaves four possibile causes to the problem:

1) The pressure regulator in the fuel distributor failing only when hot
(not likely)
2) A fuel filter building back pressure only when hot (never even heard
of that one).
3) An accumulator failing only when hot (but that's in the return line,
isn't it? Would it affect running system pressure?)
4) A fuel pump (or fuel pump check valve) failing only when hot. (It's
a new late-style pump from DMC Houston).

Any thoughts out there as to what might be the issue here? I think I
have a good grasp of the effects now, but I'm still stumbling on the
cause.

In other news... I'll be heading to Long Island this Friday night /
Saturday to visit PJ Grady and pick up my new undented passenger door
and a few other miscellaneous pieces and parts. Hopefully both doors
and the front end will be fully installed by the weekend of May 11th. I
may as well leave her rear panels off until I get the engine in
top-notch running condition. It has -got- to be easier to work on that
engine without the fascia and quarters in the way. With time running
out before Memphis, I'll take all the small luxuries I can get!

I just have to wonder about my sanity though, when after this weekend, I
will have travelled over 8,000 miles gathering parts for a car with only
1721.4 miles on it.

-Dave Stragand
VIN #05027
http://www.projectvixen.com
(Recently updated to Week 130, many new photos added!)


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