For some time now, I have notice my rebuilt 302, .40 over, exhibit engine ping, mostly when just climbing hills and in 3rd gear. Mostly very audible between 35 and 50 mph. I converted the SD system over to MAF back in late March I believe. Now, with the MAF, I lost my Knock sensor, since it isn't incorporated into the A9P Mustang PCM. The A9P worked out well since I have an AOD tranny. The engine ping is more audible/noticeable when running 87 unleaded, faintly noticeable with 89, and clears with 91 or 93 octane.

The reason I decided on checking my fuel pressure is because my Autometer Air/Fuel ratio gauge keeps leaning out whenever I give the engine throttle. There is a noticeable delay of around 2-3 seconds at times that when I'm giving the engine throttle, it goes from Stoich, to dead Lean at bottom of scale then as I'm settling out, it pushes over to Rich.

What I noticed today while checking my fuel pressure...

1. When 1st turning key on, I get a fuel pressure of around 30. Relieve pressure and try again, I get around 32, with a steady loss of fuel pressure, ending around 22-26 psi.

2. With gauge connected, I start truck, and showing only 30 psi. The needle is fluctuating rapidly at 30. When increasing throttle, the PSI falls to 28 and then slowly achieves 30. This loss and maintain isn't momentarily. It is only achieved when adjusting the throttle and maintaining it at that certain RPM, and again, as such. If you achieve the 30 PSI at 1500, and let it go back to idle, the PSI will hit maybe 32, and then fall back to 30, with no discernible increase. After you reach above 1200 rpm, the needle goes from rapidly moving to just straight and steady. When I mean it is rapidly moving at idle, its around 30, but its like it scribbling and rapid. Also note that when I removed the vac hose from the FPR, it did cause the fuel PSI to increase about 6 PSI.

3. After numerous back and forth diagnosing, I shut truck off, with gauge still connected. It shows 32, 34, almost going to 36. I'm left scratching my head here...

4. Fuel pressure regulator was changed last year because it would lose fuel pressure right after prime and with engine running, it would hardly maintain 25 psi. It was the Original Ford, 1992 FPR. The motor that was stripped and rebuilt had a replacement Bosch FPR on the fuel rail that came with it, so I yanked it and installed it. It showed at least 35+ and nothing lower than 28 psi when I installed and ran it. Im not sure if that was a PO doing before the engine was pulled, but this was an engine that was originally rebuilt by ford in '98, and cut .40 over. Timing chain was stamped '98 and so were the bearings. Also, the valve covers had a "Rebuilt by Ford" sticker on them.

5. The fuel pumps have both been replaced 2 years ago, but I have been mostly running on the rear for a year now because the front tank developed a leak after I 1st repaired it and have not been able to run it since. Both Airtex pumps.

6. I have EV6, yellow stick injectors, rated at 19lbs/hr. I see they have a flow rate of 210cc. I know with the improved 4-hole pintle/spray pattern, they do a better job at atomization. They are suppose to respond quicker to fuel delivery requirement. What I'm concerned with is whether this is part of the problem. I understand that without the correct fuel pressure, the truck can exhibit "leaning" out. Pulling plugs, shows some leaning of the fuel/ignition system, but I have removed plugs that have been much leaner, without ever realizing that or with symptoms.
I recently removed the wifes injectors from the 2000 expedition, with 201,000 miles. I cleaned them all well, with only 1 having a crack in the pintle cap. I did not re-use them, but instead swapped in a known good EV1.3 set of injectors, rated at 19lbs/hr. I have her injectors ready to use if someone can validate whether the newer EV6 style injectors are part of my problem. For reference, the part # is F4SE-A1B

Apologies for the novel, but trying to be concise as possible.

 

You still have a fuel delivery problem, you should see 40spi when priming the pump and when vacuum is removed from the regulator and pressure should never.. ever drop when engine speed increases. I would not suspect the regulator at this point you may have a cross flow problem to the front tank.

 

Front tank is completely empty. If you put fuel in it, it will leak out near the tank strap. Haven't noticed any fuel from the hairpin hole where it's leaking from.

The other option is to get a few gas cans, fill them up and dump in the front tank and then put a spill container under it so I can recovery what leaks out. At least I could get a fuel psi reading from the front pump and compare with the rear.

Also fuel PSI was around 38-39 when I removed the vac hose from the FPR, with engine running and back down to 30 when vac hose is re-attatched.

I couldn't think of the word last night, but I meant to say "The fuel pressure gauge needle is oscillating rapidly" when it's at idle.

 

Is that fuel pressure gauge fluid filled? That needle oscillation you talk about is really bad with the non fluid filled gauges, I have seen this myself and it's not something to worry about if the system produces the correct pressure values. As stated before fuel pressure should instantly jump to the higher number when vacuum is removed from the regulator or the throttle is cracked open for a split second, anything less indicates a potential clogged fuel filter, a borderline weak pump, or a possible fuel transfer problem that is siphoning off some of the active pumps volume and pressure.

 

I had a chance to take a few pictures and also try the front tank. The front tank produces near identical results as the rear tank. I've included the pictures with a few descriptions to help clarify, pinpoint at each result.

And thanks for clearing up the gauge issue. Yes, this isn't a fluid filled gauge. That would make sense with the oscillation since there isn't any dampening effect.

Engine Off, Fuel PSI near 34, was closer to 35, but just a little weeping of gas at the connector. It held here fine after getting fitting tight.


Idling Fuel PSI


Engine running, increasing throttle, PSI falling
(NOTE) The running PSI never increases above 30, no matter what the RPM is, even when cracking it open for a split second.


Vacuum hose removed & plugged.
(NOTE) The fuel PSI increased and when actuating the throttle to higher RPM's, the gauge stayed consistent @ around 39 PSI.


Only other thing I have noticed is that after shutting the engine down, the fuel PSI will continue to creep up, usually stopping @ around 38 PSI. Even if it was shut down with 30 PSI, it will gradually rise and stop at around 38.

This may or may not have anything to do with my problem. Last year I had the larger fuel hose that connects to the fuel rail, popped out. I had forgotten to snap the safety clip back on the fuel connector, so I don't know if that also meant something was wrong as well. I believe this occurred after I changed the FPR, with the Bosch unit.

Thanks for your help so far Conanski. I'm just at a lost here.

 

I understand your confusion with this, the fact that the system does produce upwards of 40psi with vacuum removed from the regulator suggests the pumps are fine and maybe the problem is with the regulator. When you remove that vacuum line does the pressure instantly jump or is it a slow buildup? If it's slow I say change that regulator.

 

I believe my problem is with the regulator. I forgot about my Ford Powertrain/Emissions Reference Service Manual (Thanks for Ebay!!). I happen to flip through and came across the section Fuel Delivery Systems. It gave me several troubleshooting options and I figured we would give the easiest plan of action a try. It said to apply 20 Hg. of vacuum to the regulator and check to see if it drops 10 Hg. in 10 seconds. If it does, replace FPR....It does.

Going to try a new FPR before going any further. I'm hoping that BWD makes a quality replacement part cuz I'm usually adamant about using Motorcraft parts.

 

Yes that's right... it shouldn't change at all in 10seconds with a steady vacuum signal attached so something is wrong with that regulator. FWIW I have an Accel regulator on my truck that has worked flawlessly for 12 years or more.

 

Well, looks as though I didn't quite diagnose the FPR well. I was checking for leakage at the hose nipple for the vac line, not the fuel return side underneath the FPR itself. It hold vacuum fine. Gonna replace filter and then im guessing it is either the injectors or the pump(s). Seems many here have had problems with Airtex pumps, maybe its just conciendence that both are able to keep up.

Also, I forgot to mention that the fuel pressure jumped right up when I removed the vacuum line, so if you have any other ideas about what that entails, I'm up for options.

 

Interesting result from changing fuel filter. After connecting the fuel pressure gauge, I notice that it doesn't oscillate now. That was really surprising, as it was straight and not fluctuation. Noticed that had some fuel pressure increase now when actuating throttle. I'm leaning towards injectors perhaps as my leaning out issue.

One question I have is I could not run the fuel pump test from the DLC connector...I have before using the wire and ground. I tried directly to the battery ground, and nothing. Is this a result of using the Mustang A9P PCM? I ran this test before back in 2012 and 2011 and never a problem, but cannot now since converting to Mass Air.

Edit: I was trying the #6 pin in the DLC connector. The short/slanted side of the connector.

 

I am having the exact same issues with my rebuilt .030 over 300 I6! After finding my fuel pressure gauge I am going to check my fuel pressure(should be ~55PSI for the I6). Also going to hook up a O2 monitor to see how it is responding.

Have you verified the EGR system is functional? That was not working on my engine and caused alot of my problems but was not a 100% fiat least I am back to 10BTDC timing with EGR operational)

How's your engine vacuum at highway speeds? The wore out 302 I had at 70mph was around 8 to 12" vac. Now with the 300 I3, its under 5" vacuum.

I too have the AOD and next person who says its the tranny causing my problem is getting a nose turned inside out(jerk at a parts store yesterday)! I don't know why people hate the AOD tranny.....

 

My vacuum is around 10-11" @ 70mph, in 3rd. If I'm in Overdrive, vacuum is around 6" @ 70mph. My egr is functioning and what I noticed since I did the Mass Air conversion is that when Im at cruising speed, light throttle, the Air/Fuel gauge is consistently switching. Now, with my old Speed Density system, with the same speed, same driving as above, the PCM would lean the system out, I suppose with full open EGR. It would go completely red, bottom of Lean, on the gauge. Weird...

I have been getting code 34 C, usually once or twice a month, sometimes not for 2 months. Changed EVP sensor, helped, but it still will come and go. I've read this has been a problem with the Mustang MAF systems. I completely removed the EGR and cleaned it really well. It doesn't leak from exhaust side and is completely sealed. I did find though it is leaking from the intake shaft area. It holds vacuum but I believe the guide in which the shaft runs up and down has worn a groove inside. It leaks but it operates. I know it has to be causing a problem, but I'm leary if buying a new one will fix it. It's rather expensive for a Motorcraft one. I may do the soda can trick, block the EGR off and see if it will bring me a 1" or 2" increase in manifold vacuum.

 

I verified my fuel pressure and it was in specs of 55psi at idle, goes up to 62psi without the fuel pressure regulator vac line attached. My fuel pressure gauge is too short so I can't run down the road with it.

On the EGR issue, you mean the EGR valve shaft? If that was leaking you get a exhaust leak there and most likey will melt the EGR valve diaphram. I had that happen to me before.

 

Digging further into the problem...EddieC1564, may want to check this on your 300...

I have noticed that when 1st starting the truck, I never get out of lean, unless I give it throttle, then the switching from the O2 is shown on the A/F gauge. This was also predominate as well with my SD system as I always would have a near stalling effect after the "Known" high idle concept. This could be corrected IF I disconnected the vac line running to the TAB/TAD solenoids. I never gave it much thought as I had problem with the system in the past, but would somehow correct it self...

Well, lets move forward...I found that if I pull vacuum on these 2 solenoids, they hold as they should, until I start the truck. Ok, so I disconnect each one. TAD is holding, TAB completely dumps all vacuum, and it keeps dumping, losing all manifold vacuum, till around 5" Hg. Did some testing on these solenoids, they're great, no problems. All vacuum lines hold. Now, it gets interesting! I decided to check the ACTUAL voltage coming out of the TAB connector line. Well, it's 10.37, acceptable, but when the truck is started, it pulls 13.7 and it NEVER switches...Weird. At the same time, there is NO CEL for this. There should be! It never came on in my 20 minutes or so of testing.

I'm pulling my wiring schematics and double-checking my MAF conversion, but I'm HOPING that someone with a little more insight can provide me with some more info on why the TAD solenoid connector, from PCM, isn't switching, causing the valve to hold and then dump correctly.
This was also a problem before with my OEM SD system, so I'm fairly confident, since I have no CEL or stored codes.

 

I think I found my problem, bad ole boozed up gas(E10) has "cleaned" my tank and lines and plugged up the new fuel filter. I replaced the filter back in January and never though of this till my friend told me of the boater's having exact problems.

Turns out in SW Florida area we finaly recived the E10 gas in March or April. That crap is plugging up filters and eating up carbs in lawn mowers. He replaced a fuel filter in a Mercruser EFI engine back in Febuary, the owner came back with issues we had at full power(lack of and engine ping!) Well 1st thing boaters do is clean the fuel tanks, lines and replace filters(figure water got it) That fixed the problem there. Out of curiosity he drained the fuel filter, it had black crud comming out of the inlet side and it was plugged to the point he could not blow through it.

SO I pulled down my fuel filter and what I found..... its full of black crud!! Well a new filter is going in and hopefully THAT fixes my problem. Never before I had a fuel filter plug up like this(not counting the azzhole sugaring my gas tank 20 years ago). Fuel filters should last years.......

Wonder if my Dad's 06 F150 missfire is caused by this.... still missfireing after replacing 8 of Ford's "mistake"of a spark plug design(yep the LAST one broke off)......