Simple question, really, but need other's to make sure I'm not missing something.

I have a '93 Taurus 3.0, got it for a few hundred bucks, and am going to resell it, so nothing I do is going to be big bucks for this thing.

This thing hesitates quite a bit, gets a little better when warmer, but not much. It pops out the intake when it's not fully warmed for 10 minutes or more.

I pulled the vacuum line off the fuel pressure regulator, and it didn't affect the idle at all. I put a hose on the regulator, and sucking on the hose (applying vacuum to the regulator), the idle didn't change AT ALL.

Shouldn't it really affect the idle a lot ?

If so, looks like I might change it to try to alleviate the problem.

BTW: I already checked the MAF, and it was filthy, but only affected the hesitation slightly, making it slightly better, but not gone.

PS: I know all the other things to check, but to me, applying and/or removing vacuum from the fuel pressure regulator should have seriously affected the idle, right?

 

Wow, no takers? Turns out, I checked the pressure with a guage, and it looks "normal" ... I'm still investigating if 35 at idle, and 45 at load is "normal" but looks OK.

I just don't like the gas smell coming from the FPR vacuum hose when I pull it Might change it anyway just because it seems the diaphram is a'goin'...

 

Have you tried pulling codes? The EEC-IV system on the '93 can store substantive codes without tripping a CEL. You don't even need a meter or anything, just watch the CEL blink: http://www.shophoenixproject.com/eec/eec.htm

If there's no liquid fuel in the FPR vacuum hose and the pressure test seems normal, then I would think the FPR is OK, but who knows? (Does the FP "hold" for a minute or so and stay within the specs for KOEO?) How about a new fuel filter? Cheap and pretty easy to replace.

The ECT is another cheap sensor and relatively easy to replace, as well. Since it has such a bearing on air/fuel mixtures, it might be worth replacing. And I would definitely recommend cleaning the MAF sensor if it has not been done in a while (did you clean it?).

Also, are you sure it's fuel (and/or air)-related? What do the plugs look like? Could it be time for a tuneup with some cheap plugs and wires?

 

I cannot comment on the exact specs for a Taurus, but I can on an Explorer. The vacuum hose removal probably will NOT result in any noticeable difference in running, but can clearly be seen with the pressure gauge attached. The pressure should run in the 30-35PSI range with vacuum hose attached and engine running, and 5PSI higher when removed and engine running. If it does not do this, or the pressures are out of range (tolerance) replace the unit.
Also if raw gasoine is present in the vacuum line, then diaphram is leaking and unit should be replaced. A third test should be done to see how long the regulator maintains pressure after engine is shut off. It should hold a good percentage of pressure for up to 30 minutes or more. If not, you need to determine if regulator is leaking past, or an injector is leaking. On my Explorer, I disconnected the return line at the frame connection point, dropped the return line into a plastic coke bottle, charged the fuel rail, and observed the flow when key was shut off. My regulator was leaking down and all pressure was lost within 3-5 minutes resulting in hard (long cranking) starts and excessive backfire on starting. Replaced it and all was well with the world again.
Dialtone

 

Mine was stuck giving my a constant 65PSI...lol, around 6-8MPG! It bled down to 0 in a matter of seconds. Replaced it and now I get around 13mpg.

I dont know what the pressure should be on a 3.0, but you definetly need a fuel pressure gauge. If the regulator is stuck closed, you will notice a very fast bleed down. Of course, it could be the injectors, like dialtone said, but its not likely.

 

Well, it wasn't the FPR, which I found worked just fine at 35PSI at idle, and up to 50 under load (no vacuum).

The timing was 30 degrees retarded! It appears the tranny was worked on at one point, and the wires to the module on the dizzy are short, and if the engine was left to sag down, it would pull on the dizzy.

Thanks for all the ideas!
art k.