Thermo Time Switch for '87 5ktq? [was Fuel Pressure Testing - 5ktq - where to tap?]

[Ben Swann]

Well something would seem to be.  Here are the results of the pressure
testing.

Note: I used two guages and can shut off either side.  The system side
guage tended to read a little higher, so I give a range, or an average of
the two.

Ambient temp = 67 degrees
Engine cold, not started, warmup reg. connector unplugged:
Cold Pressure(engine not running, fuel pump only): 15-18 PSI
System Pressure 88-91 PSI
Shutoff Pressure, engine not run - System side only: 50 PSI
Shutoff Pressure with Control side open: 43-45

Engine started,
Control Pressure: 30 PSI upon startup
System Pressure: 90 PSI upon startup
Control Pressure 5min into warmup(fan not running) 35 PSI
Control Pressure (Fan just coming on): 38 PSI
Control Pressure ( Fan Cycling): 40-45 PSI

Residual Pressure(s) -
Hot just after shutoff: 47 PSI
5 min after shutoff: 45
10 min: 43
20 min: 42
1 hour: 40

I checked about 4 hours after testing: 0 PSI - there was total leakdown in
the system!

I noticed when I started it up to move, engine cold, with warmup reg still
unplugged, engine started poorly as usual, but had a nice idle(not lopy),
but more like a purr.

So, what does this mean?  It seems the pressures are near spec. from what I
can tell, but to have no pressure in the system after it has been sitting.
   Also, it tend to be hard starting even after 5 min. when hot.

Things done -
New injectors about 2 years ago, only have about 20kmi on them.  This whole
thing is like deja vu, as I ran pressure tests before replacing them
experiencing a similar hot start.  The car has started and run beautiful
until after rebuild ( well it did kind of have a deceleration exhaust pop,
which I attributed to exhaust manifold leak).

Replaced 2 of 3 o-rings in system check valve.  Outermost one (Control
Pressure reg side not replaced), because the mechanism seemed to be a press
fit and I didn't want to break.  How do you replace this one?

Currently, I have both valves closed, to see if either or both sides have
leaked down after sitting.

Also, checked the thermo sensors - both were 0 ohm hot, 1.5k ohm cold.  I
would think since both had identical readings, they are both good, except
for the 0 resistance when hot.  Perhaps my meter is not reading right.

Also, in addition to going over all potential vacuem leaks many times, I
did the propane test, which revealed nothing.

Anyway, it would be nice to nail this problem.

Thanks for the tips so far.

Ben

'87 5000 tqa Pearl - Engine rebuilt and running...Elgin 270i260e cam,
lifters & techtonics springs, new rings and bearings, seals.  T03/K26
hybrid turbo, 2-Piece Exhaust manifold, highflow cat and 2.5" Stebro
exhaust.  Bypass valve and supplimentary fuel injector installed(but not
connected to fuel yet) in intercooler. 200 Flywheel, Clutch and Pressure
plate.  Using existing QLCC chip & Schrapnel Knob for control - set for 1.7
bar max during break-in.

On Thursday, April 11, 2002 5:08 PM, Huw Powell [SMTP:human747 at attbi.com]
wrote:
>
> > Yeah, I got the guages hooked up, and so far don't see anything out of
spec.
> >
> > I have not done warmup tests, only cold with fuel pump running, engine
off.
> >
> > System Pressure = 88-90 PSI
> > Control Pressure = 30 PSI
>
> I *think* that control pressure should be lower when cold, more like 15
> psi or so. (goes to 45-50 or so when warm)
>
> So your warm up reg might be at fault.
>
> --
> Huw Powell
>
> http://www.humanspeakers.com/
>
> http://www.humanthoughts.org/
>