No I have not. How would you do that?

__________________
1999 Ford Ranger XLT 2.5l 2wd (2k miles on the rebuild)

Gain access to a fuel pressure gauge that will attach to your fuel rail. Most have a 'bleed port' with small diameter tubing attached. You can run the vehicle with the gauge attached, and press the 'bleed valve' to allow fuel to flow into a suitable container(one with measurement marks). Do that for a measured amount of time, such as 15 or 30 seconds. Calculate the delivered volume for a minute(multiply by 4 or 2), and then multiply that by 60 to get volume per hour, and convert that to gallons, the common measurment, GPH, gallons per hour.
Stuff on the pickup sock(filter) can limit fuel flow, as can a semi-plugged filter or a failing pump.
tom

I would like to know the results if you can get this figured out. I'm having the same issue. Same symptoms at idle, runs choppy, same fuel pressure (60-65 PSI) that drops once shut off.

Hey guys sorry its been awhile I was just learning to live with the problem because nothing I did seemed to fix it, but driving it really makes me upset with how poorly it idles. I do not know the gpm I haven't checked, but I will try to tomorrow. I just don't understand how a low volume could affect the engine at idle when the problem goes away at high rpm which would demand even more fuel. I still question a vacuum leak to be the cause, but not sure how to find them better than starter fluid because that has helped me find nothing.

__________________
1999 Ford Ranger XLT 2.5l 2wd (2k miles on the rebuild)

Been a while. Correct me if I get it wrong.
- bad idle, lumpy, shakey
- backfire if you open the throttle quickly
- 65psi fuel pressure
- fuel pressure drops to ZERO quickly after shutoff
- can go down the highway ok, no lack of power(not mentioned exactly)
...
You have a leakdown problem, which could be a stuck injector, dumping excess fuel into the intake, which is et by the engine at high speeds, but is too much at idle.
I believe the fuel pump has a check valve, but the returnless(65psi system??) systems do not have a check valve in the regulator. Limiting leakers to pump & injectors.
You could pull the fuel rail & all injectors, and see if any leak when power is applied to the pump. If you do, be sure the injectors stay in the rail or you'll have a heckuva mess.
Be prepared to put out a FIRE, or have catch-cans (soup cans?) to prevent fuel spilling all over the place.
The injectors should not squirt a durn thing when the key is turned to ON, period. If they don't your leakdown is likely in the pump check valve.
I do not remember mentioning it, but the ribbed tube that feeds air to the throttle body could have damage, gaps in the ribs, that only shows when the tube is flexed. Leaky tube will scramble the idle as it lets in unmeasured air(lean mix).

tom

It doesn't backfire necessarily, just stumbles and hesitates greatly when you quickly hit the gas. Basically bouncing your foot on the pedal. Biggest thing is it shakes like crazy and RPM is all over the place. Also evidence that this is a problem and not just me being crazy is the voltage fluctuates a ton at idle because the rpm is inconsistent. I have inspected the intake hose and from what I can see that is fine. I have already checked the injectors for leaking. Also no smell of gas in oil which I am told is a possible sign. While looking at fuel trims through OBD II diagnostics I can see the engine is running lean with high fuel trims so also leads my belief that the injectors are not leaking as this I believe would cause it to run rich. One thing is when I did take it in the shop to get it smogged they found a vac leak coming from where the oil seperator (the black can the pcv valve goes in) connects to the block. So I took it out and put some gasket seal to seal it. One thing you could tell me is if this can just sits in there with a bolt in it or if it is supposed to be pressed into the block to make a tight fit. Other than that no vac leaks. sorry for the long reply just trying to give you the most info I have. Thank you so much for your time. BTW if it helps the fuel trims are LTFT: 15% and STFT: fluctuates within spec. When running at about 2500 rpm on highway LTFT drops to 7% which is more in spec but I would like to see closer to zero especially on a newly rebuilt engine. Thank you again.

----------

Also should mention sometimes it runs perfect and I have no explanation as to why but this is sometimes. Maybe once every month so close to never.

__________________
1999 Ford Ranger XLT 2.5l 2wd (2k miles on the rebuild)

Sorry, But I am lost... too many posts & different problems.

I'd do two things: Check idle and running fuel pressure. If it drops when you step on the gas, it will cause the engine to stumble & buck.
Check the MAF, once again if you've done so already. It will also mis-report airflow and fool the computer into spritzing the wrong amount of fuel. The same can occur if the fuel delivery volume is limited or the pressure too low or drops when you goose it.
tom

Okay I will try to check later.

__________________
1999 Ford Ranger XLT 2.5l 2wd (2k miles on the rebuild)