2002 SCAB 5.4. Is the fuel pressure schrader port "special" on this thing? I have a hot no start That i am diagnosing i believe i have NO FUEL.... but i also do NOT have the correct adapter either...SEEMS like? is there something special about this schrader? other than it is very deep?

my tester.

 

I dunno. I have a similar looking test gauge that fits the valve.

 

It's your pressure gage fittings.
Nothing special about a Schrader valve thread.
It's been around a long time.
Same as used in an auto, Bicycle or other implement tires.
.
Hot restart is no different than cold starts (for fuel pump control).
The difference is in the temperature readings the PCM uses, of intake air [IAT], and cylinder head temperature [CHT]
To set fuel table, ignition timing and IAC opening.
The pump runs the same either way.
The system has no other way to know the difference..
.
Upon cranking, the Crank sensor sends it's signal to the PCM to operate the fuel pump via a timer circuit. This in turn operates a relay that passes separate fused power to the pump.
The design is done this way so the fuel pump cannot feed a fire. When the crank stops the pump stops (PCM timer stops) plus a crash sensor to open the pump circuit under high impact.

 

On the hot no start, what happens if you floor the gas? If it starts, you probably have leaky injectors. What about if you put the gas down just a bit? If it starts, you may have a sticky IAC.

Is that gauge a OTC 5630? If so it's junk according to some Amazon reviews. The little adapter in the pic supposedly is for Ford fittings.


This one appears to be better quality:

 

adapter screws onto schrader.....but the "valve: on the fuel line is quite recessed not allowing the valve in the adapter to contact it.
the intermittent no start:
spins over FINE....but does NOT run....nor does it sound like it wants to.....either NO ignition or no fuel. I do NOT have any noids....YET to check ignition. It has done this about 3 times now, only when warmed up. Go into store...exit...(so about 5-10 min sitting) then get this no start. I turned key on...wait 5-10 sec...then off ( I can NOT hear fuel pump) go again.....then maybe 3-4 time I will give it a start....YEAH I runs.

 

If you can't hear the fuel pump when you turn the key on, the fuel pump is probably on its last legs.

If you can't get the gauge working, hit the pin in the Schrader with a small screwdriver. If fuel squirts out you have pressure.

 

duhhh....figured out the start issue.(I think) Air filter (K-N) was loose to the hose assembly AFTER the sensor....sucking air
but the schrader valve is/was an issue...seems the valve assembly is .120 below the top surface. I measured some others i had laying around ....they measure .050 below top surface. Measured adapter..it allows the "plunger" to go .060 after top surface contacts seal.....so there is NO WAY the "plunger" COULD contact the fuel rail schrader "valve"........so (since i had another after intake swap) I simply removed the valve assembly ...remove valve....ground -.070 off top surface, refinished edges and installed on vehicle. Works as it is supposed to.

 

after doing a 15 min leakdown test.....on the fuel rail. I know why I couldn't hear the pump....it's still holding 29-30 psi (same as run pressure at idle)

 

That's pretty close to the lower limit (28). With it idling, pull the vacuum hose off the FPR, what does the reading jump to?

 

Goes up to 40 without vacuum

 

Then the pump is OK. The FPR may be on its way out.

^^^^^^^^

 

another question about fuel control. Do modern ECM's turn off fuel if: cranking while throttle is WIDE OPEN? i know back 100 yrs ago the early electronics WOULD shut off fuel delivery during cranking if TPS was full throttle....like cranking a flooded engine ..or to provide an ignition "health" check.

 

My truck's fuel pressure checks around 30 psig running and it's been that way for years and it runs just fine.

 

Yes, that's why I suggested to floor it. If the injectors are leaking, it's flooded and this will clear it.

 

has anyone ever found a different fix for the recessed schrader valve? My 01 king ranch 5.4 is exactly the same way. Can't test fuel pressure due to valve not high enough for the ford adapter to open the valve.

I did unscrew the valve some and it stated to work but it also leaked all over the place.

Sorry for resurrecting an old post.