possible fuel pump issue

[racsan]

twice this week my '94 2.3 has died right after starting. i got it to fire on either both times and eventually would run on its own. i bought a guage to see what the fuel pressure was running cause when i suspected it was a fuel issue i had put a small scewdriver in the fuel rail test port valve, expecting a spray of fuel and there was nothing. well with the guage on i had no pressure at first, engine wouldnt start, finnally for no reason i had pressure and it started, was running right at 30 psi. can drive down the road and seems to have no problems getting enough fuel, accelerates through the gears just like always. i dont know if theres a relay/electrical issue or a pump about to die completely. seems a pump should either work or not work, not be a intermittant problem. and its never happend once its running, its always been a start-up issue. im sure sometime its going to be completely dead in the water. any thoughts/ideas?

 

[alwaysFlOoReD]

I suspect wiring. I hate electrical gremlins. I see RonD is looking at your post so I'll let the master speak first.

 

[RonD]

Any electric motor can be intermittent.

Ever "tap" on a starter motor to get it to work?
Or transfer case motor?

Fuel injection systems are designed to hold pressure for MONTHS, not minutes, hours or days, MONTHS.

So at any time you should see no lower than 20psi at the engine, even after it has been sitting for a few months.
30-40psi engine running is normal

So you are losing pressure
In 1997 and earlier Rangers there is a Fuel Pressure Regulator(FPR) on the engine, it is connected to the fuel rail and fuel Return line, there is also a Vacuum hose connected
FPR is just a Valve with a spring, spring is set for about 42psi, so at 43psi valve will be pushed open and release fuel and pressure, to flow back to the gas tank, until pressure is at 42psi again
The Vacuum hose adds pressure against the spring, so with engine running average pressure will be 35psi this keeps pressure from bouncing around as fuel demand changes, low RPM and high RPM

Fuel pump only runs for 2 seconds each time key is turned on, but you can turn key on and off as much as you like, to build up pressure in the system.
2 second thing is a safety feature, key on engine off 2 second rule prevents electric pump from continuing to pump out gasoline in the event of an accident, key on engine off.

So FPR holds pressure at engine end, inside the fuel pump is a Check Valve, Back flow preventer, simple a flap the is pushed open when pump is on and then closes and held close by pressure when pump is off, so this holds the pressure at gas tank end.
If you have 30psi engine running and when you shut off the engine the pressure drops to 0psi then you have a leak
If you don't smell gasoline then either FPR or Check valve is leaking fuel back to the tank.
You can remove the Return fuel line on the FPR, put a rag down under FPR, and then cycle key on and off, no fuel should come out of Return hose port in FPR, not until pressure is above 42psi approx.

It is also possible for fuel injector to leak, but you would usually get Rich Codes and big drop in MPG

 

[racsan]

i have noticed a gas smell every now and then, looked for a leak but didnt see anything. once in a while on a cold start it would seem to not be running on all 4 for a few moments, but would clear up before i got to the street, would run fine on the road. cant really check milage as ive changed tire size and rear axle ratio so speedometer is about 10 mph off. i just thought one of the injectors was bad, have a set from a '90 302 i was thinking about putting in (im certian they will fit, years ago i changed injectors in my '88 2.3, so still have the other 4 injectors from the 302) be good if i dont have to change a pump, between the price and the hassle of taking the bed off to access it, yuk. i have the pump from my 97 but the sender for the guage doesnt work on it. plus if im changing a pump id just as soon put a new one in it due to the hassle of changing it. i'll look at things again tomorrow. makes sence about pressure loss, i thought i should have pressure at the rail with engine off and seemed odd no fuel came out the schrader valve on fuel rail when i checked for that the first time it wouldnt run for me. thanks for your input.