OK I changed my spark plugs today because they all were heavily fouled so I also decided to do some other tests to find out the cause. First of all, my AFPR wasn't set correctly; I didn't know you had to adjust it w/o the vacuum connected. I had it set @ 45psi but when I disconnected (and stopped up) the vacuum line it read 55psi! So I backed it back down to 45psi and reconnected it. Hopefully this takes care of the problem but I decided to do a (leakdown?) test anyway and here are the results. I turned on the ignition and primed the fuel rails for a minute then turned it off and watched the FP gauge.

44 psi - 00 min
40 psi - 04 min
35 psi - 08 min
30 psi - 10 min
25 psi - 14 min
20 psi - 18 min
15 psi - 23 min
10 psi - 29 min
05 psi - 37 min
00 psi - 46 min

What I want to know is is this just normal fuel pressure bleeding off back into the fuel tank thru the return line or is this indicative of faulty / leaky injectors? Thanks...

 

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Do you have trouble starting the car after its been sitting for longer than about 10 min? That's about how my pressure dropped off when I was having problems starting.

You can figure out if its injectors quite easily. Start the car and shut it off. Now pinch off both the feed and return lines and watch and see if pressure still drops. If so you have at least one leaking injector.

I ended up putting on a new set of Accel 23# and have had no problems as yet.

Bob

 

Sorry, but just watching the pressure bleed down doesn't tell you anything. It could easily be either the regulator or the injectors, or even the check valve in the pump.
You can check the injectors simply by pulling the fuel rail out of the intake, putting dry paper unde rth einjectors and pressurizing the system. You eliminate FPR leakdown or fuel pump check valve by clamping those lines closed with pressure in the system. Thats all there is too it. Don't guess, just check. It's faster, easier, and guaranteed to be the right answer.

 

That looks pretty normal to me. i just replaced my injectors, and they bleed off at about the same rate.

 

Just my opinion, but if you still have 20 PSIG after 15 minutes, fuel leakage/flooding is NOT your problem. That doesn't necessarily mean that the injectors are O.K., just that they're not leaking heavily. You may still have fuel atomization problems, poor spray patterns, unequal flows, etc. That leakage rate is more indicative of a regulator or fuel pump check valve leaking back, and is inconsequential.

But that's just MY opinion. If you want a professional opinion, check with Rich at Cruzin' Performance for the definitive answer. Don't be surprised if he suggests you send you injectors in for service. If he does, he's not just trying to drum up business. I know he's been utterly swamped lately and can barely keep up. Frankly, it seems like he'd rather get out of that part of the business to concentrate on other things, but he still does it, and does it very well. If you doubt that, ask a few others who have used his service. He knows his sheot in injection systems. He might tell you that I'm "full of it" and that you have a bad regulator, pump, or injector. If so, I'll defer to his opinion.

 

Ed, are you saying that you still have to clamp off the feed and return lines for this test? I have this same problem withmy car. Takes a little whileto start when cold and when it finnaly does it barely wants to stay running unless I hitthe gas pedal. Warm start ups are fine. And I smell gas under the hood but there is no leaks. also will clamping the lines destroy them.

 

Cold start problems are not likely caused by injector or fuel pressure leakdown. Those are causes of hot start problems.

 

ok so what can cause the car to have a cold start problem. My car will turn over and then stumble and just die. it will doit a few times before it catches and keeps running, unless I give it gas after the first turn over

 

very true but the tiniest leak can cause the car to need to prime after the injectors have leaked away the volume of fuel from the rails. I would suggest some injectors being that ford injectors are so cheap if they turn out to leak this is just one of many options