Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: joker77_2005 on January 24, 2009, 07:57:51 AM

Title: fuel pressure spec
Post by: joker77_2005 on January 24, 2009, 07:57:51 AM
what is the fuel pressure spec for a 84 bird 2bbl fi
at idle i have about 42lbs but it doesnt change when i open the throttle
mike
Title: fuel pressure spec
Post by: BadShoe on January 24, 2009, 10:32:23 AM
I think I remember that's a good reading for a CFI 5.0L and there is no pressure change on rev up with a CFI system.
Title: fuel pressure spec
Post by: jcassity on January 24, 2009, 11:33:46 AM
stock idle is 40lbs

as throttle is applied, the fp will decrease under load (ie-transmission is topping out between gears)

check out my diy link below with pretty much everything ive said below to include links to topics here about various things.

To test the fp correctly so you can simulate problems, connect fp tester then duct tape the guage to your windshield.  Drive your car and watch your guage.  If the presure drops below 25psi between transmissin gear shifts, I would be looking at a replacement.

A good replacement is the 1990 supercharge 3.8L fuel pump you can purchase at your parts store.  It is just the pump only and you reuse your housing and rubber boot assembly.

typically people find the 2'' long 90deg bent rubber hose in the fuel pump assembly has a crack in it.  This causes the pump to dump fuel back into the tank and some up to the engine.


The CFI has a stock adjustable fuel presure regulator also.  the small freeze plut atop of the FPR which is mounted on the top of the cfi can be drilled out to reveal an allan screw adjustment.  1 turn equals about ~@ 2psi.

If your wanting to wake up the air flow ,, remove CFI and take it apart so that you can hone out the upper half just below the butterflies.  The 3.8CFI has a huge air restricton where as the 5.0 is not so bad but still has some form of hour glass bottle neck.

In addition, there is a tiny tear drop filter screen at the top of each injector which can be removed with no ill effects that i saw.  You have the option to change your main fuel filter out more often to compensate for this or install a secondary filter up on the line that feeds the pass side fuel feed line.  If you want to cure that age old "hesitation" issue when you stop the gas but there is a huge delay in response,,then pull the injector screens.

In a way, CFI guys are lucky when you need a random amount of gas for yard work.  You simply disconnect the pass fuel feed , stick that end into your gas can, jumper the tan/light green wire at the eec test connector to ground, turn on the key, the fuel pump will run full time.  when the can gets full, turn key off, fuel pump will take longer than usual to shut off like 5 sec then it will cut out.


scott
Title: fuel pressure spec
Post by: jcassity on January 24, 2009, 11:36:12 AM
................................
Title: fuel pressure spec
Post by: joker77_2005 on January 24, 2009, 12:38:26 PM
with a low pressure pump in tank,a high pressure outside how wud i do the supercoupe pump mod?
the problem i am having is the engine will not start on its own,i have to push pedal to floor while cranking it over
mike
Title: fuel pressure spec
Post by: joker77_2005 on January 24, 2009, 01:07:19 PM
my fuel pressure wont move,engine running,in gear brake applied gas pedAL to floor trying to get a tire to spin and the pressure remains steady at 42 lbs butt it wont break loose and spin.it acts as if the exhaust is clogged butt i know its not,no ler or tailpipe yet
Title: fuel pressure spec
Post by: TurboCoupe50 on January 24, 2009, 03:21:27 PM
Quote from: joker77_2005;253347

the problem i am having is the engine will not start on its own,i have to push pedal to floor while cranking it over
mike


Have you checked codes(I'm guessing no)??? You most certainly have a issue other than fuel pressure...
Title: fuel pressure spec
Post by: TurboCoupe50 on January 24, 2009, 03:22:30 PM
Quote from: joker77_2005;253347
the problem i am having is the engine will not start on its own,i have to push pedal to floor while cranking it over
mike

Have you checked codes(I'm guessing no)??? You most certainly have a issue other than fuel pressure...

May very well have a TPS or Idle speed motor problem...
Title: fuel pressure spec
Post by: joker77_2005 on January 24, 2009, 03:29:50 PM
nocodes what so ever,at idle tps shows 1.003 volts with a smooth transition to wot 4.57 volts
the idle speed selonoid is good,will hold idle fine,also jacks the idle up when i turn the a/c on
whats is the vacum spec that these engines should pull at idle?
mike
Title: fuel pressure spec
Post by: V8Demon on January 24, 2009, 04:42:11 PM
Quote
my fuel pressure wont move
 
Quote
whats is the vacum spec that these engines should pull at idle?


Here's an interesting animation for vacuum diagnostics:
http://sbftech.com/index.php/topic,3020.0.html
Click on each scenario. It's a very nice tutorial.

For the exact values, I'm not sure, but I BELIEVE it's gonna be around 20" Hg @ idle...
Title: fuel pressure spec
Post by: joker77_2005 on January 24, 2009, 04:57:29 PM
you guys are pretty nice,most other forums i go on i get buttholes telling me to use the search,or figure it out on my own
anyway at idle i have about 15in of vacum,i am thinking the egr valve is not closing fully,i tried cleaning the carbon off butt still have the prob and the egrp sensor is showing 1.30-1.40 volts at idle,and i belive it should be closer to 1.0 volts.with that leak at the egr valve the fuel pressure reg is probly not getting enough vacum to regulate the pressure down any
does that sound right?
mike
mike
Title: fuel pressure spec
Post by: TurboCoupe50 on January 24, 2009, 07:37:55 PM
Quote from: joker77_2005;253391
y.with that leak at the egr valve the fuel pressure reg is probly not getting enough vacum to regulate the pressure down any
does that sound right?
mike
mike


That's a possibility,  but remember this... Vacuum plays no part at cranking speeds, whatever you starting problem is, it isn't vac or fuel pressure related...

Going to full throttle puts the EEC system in dechoke mode which shuts off the injectors(to clear a flooded engine)... Only thing is I'm not sure a '84 CFI has this function, I know it's on all SEFI EEC systems... Unfortunately I don't have any info older than '86...
Title: fuel pressure spec
Post by: jcassity on January 25, 2009, 03:00:33 AM
Im not really clear on what your problem is.  You hinted at it on your previous post saying it "acts clogged".  Initially I didnt think you had a problem at all, but a question.

What specifically is the car doing wrong?

You said no codes at all,, with that being the case you would have one code only so what was it?  You should have gotten code 11.  You cant avoid getting atleast one code if it's done right.

With no codes,, your running in open loop.
Title: fuel pressure spec
Post by: joker77_2005 on January 25, 2009, 04:54:23 AM
yea the code 11 i ignore on koer, only code.
on koeo i get 11 ,and 34 egrp out of spec,which led me to check voltage on the egrp which was 1.35 ish volts.no cel while it is running
when i start it i cold i tap the gas to set the choke and it fires right up.
after it is warm i have to all but wot to get it to start
driving down the road moderate throttle is runs ok,kinda lacks power.
on wot it acts sluggish with no power,like the exhaust is clogged.
if i let off of wot just a little then it gains a little power but still acts slggishs
all filters,plugs wires,cap,rotor,pcv are new
mike
Title: fuel pressure spec
Post by: TurboCoupe50 on January 25, 2009, 09:34:08 AM
Ummm(looking at ceiling) Assuming the iginition system is Ok, WOT throttle problems are commonly caused by a weak fuel pump that cannot keep up with demand... Have you checked F/P while driving the car???
Title: fuel pressure spec
Post by: joker77_2005 on January 25, 2009, 02:07:07 PM
fuel pressure is constant at 42 lbs wether the engine is idleing or driving down the road at wot .it does not fluctuate
with the koeo i get the 2 sec puel pump prime,pressures goes to 42lbs and holds that pressure for roughly 15mins b4 it starts to leak down very slowly
mike
Title: fuel pressure spec
Post by: jcassity on January 25, 2009, 08:45:46 PM
You did check the fuel presure while driving???? 


Next up would be to check and verify you have nice bluish white spark.  anything short of that points to a TFI or Stator on/in the distributor.

BTW,, its an EVP sensor but i get what your saying though.  Your CFI base plate could also be broken but you did not meniton if you idle a little high or had to recently back down the idle.

also, the CFI base plate itself could be carbon clogged and therefore it will not actuate the evp properly.
Title: fuel pressure spec
Post by: joker77_2005 on January 25, 2009, 09:47:14 PM
yea yea that was while driving,
i sprayed around the intake , baseplate gaskets with carb/choke cleaner and didnt get a change in idle speed,still idles at 15-16 in of vacum
i have a good clean spark,all the secondary ignition componants have been replaced
i am kinda leaning toward the egr valve,after i cleaned the passages out i could still blow some air threw the ports even tho it was closed
i havent touched the idle speed,but it does idle a little low
mike
Title: fuel pressure spec
Post by: jcassity on January 25, 2009, 10:24:13 PM
look down in the distributor where the metal fins pass through the stator.  ther eis a manget on the inside part of the stator.

remove the metal fin device and see if there are metal chips or debris on the magnet.

If you have good fuel, good spark, no vac leaks along the cfi, then you problem must be mechanical that would not generally trigger a code. 

The ACT sensor has a little tear drop part that gathers air flow info and converts that to an eec input.  See if it is dirty and clean with a decent evaporative cleaner.

I suppose next would be a compression test.
Title: fuel pressure spec
Post by: joker77_2005 on January 26, 2009, 11:07:37 AM
yea compression check yeilded 140 across the board ,the distributor had some corrosion powder down inside ,everything else inside was clean
timing is sitting at 7* as per the sticker,timing doesnt jump around
mike
Title: fuel pressure spec
Post by: jcassity on January 26, 2009, 12:22:53 PM
do you have the duraspark ignition system?
Title: fuel pressure spec
Post by: joker77_2005 on January 26, 2009, 12:37:37 PM
tfi?has the ignition module on the side of distributor
mike
Title: fuel pressure spec
Post by: softtouch on January 26, 2009, 02:50:29 PM
Quote from: joker77_2005;253695
timing is sitting at 7* as per the sticker,timing doesnt jump around
mike

Is this with the SPOUT disconnected?
Title: fuel pressure spec
Post by: joker77_2005 on January 26, 2009, 02:53:15 PM
yep
Title: fuel pressure spec
Post by: jcassity on January 27, 2009, 10:22:41 PM
well then,, theres only one thing remaining.

PUll the cfi and chip away at the carbon buildup under there.  Thats all thats remaining.  either that or your injector screens are clogged up even though you've probably looked at them pulsing.

If your getting 42 psi while driving and it does not move when the transmission is shifting, then you are the only one on earth with a stock 60lph bosch pump that does that.  Obviously the pump is good, however, using the pics I posted, you could install a better pump in the tank along with minor wiring mods to get a SC pump to work.  I do not have that exact wiring diagram for your two pump setup but Softtouch probably does.

If your getting nice blueish white spark, then your ignition is good.
If your compression is even and such then everything is sealing up good as far as rings/valves go.

Your vac pres reading could be misleading because of were you are taking it.

It might be helpful to undo the vac line leading to the rear CFI gold fitting and plug it off. get the car started and see if that fitting is sucks air.

If the CFI has never been off, its time to pull it and clean anyway.  while you are at it, take it apart and yank the injector screens.

Can you rig up a little bulb / bulb socket with pigtails to each injector connector and crank the engine so the light blinks consistantly?-ie power delivery to the injectors in even strobes.

Also, when the car is shut off after you got it running, fish you a paper towel under each injector for a few minutes and check on it later to see if fuel dripped with the car off.

What color are your injectors??dark blue like?  If they are green, then let me know.

BTW, dont unplug / replug the sprout with the car running.

I believe you have that one odd ball CFI which has the old carb like automatic choke pull off on the pass rear side,, correct?
If so, then you dont have an idle control motor but a vac operated plunger on your trottle linkage driver side.
Title: fuel pressure spec
Post by: joker77_2005 on January 28, 2009, 01:27:22 AM
yea i have the odd ball cfi
i pulled the cfi off and it is pretty dam clean and shiny,as is looking down into the intake...no carbon buildup at all
i am taking vacum readings from the brake booster line port on the intake/cfi
fuel injecters dont drip after the engine is shut off,holds fuel pressure for at least a half hour...i checked after a hour and had about 15lbs
a noid lite on the injecter connecters shows even pulses
both injecters have a nice clean wide spray pattern
engine has no blowby ,capping off the pcv valve has no effect
even the egr plate had very little build up to clean off
i did order a new egr valve as the old one ,the plunger did not seal up airtite
i borrowed a borescope/cam from snap on and took a peek in the plug holes,pistons and walls look fairly nice.i/e no carbon buildup
should the fuel pressure stay the same,or should the pressure drop some at idle and then go back up off idle,like the fox mustang efi?
i am not wanting to turn this into a hot street car yet,
i have a 89 stang that does low tens, and a 89 cougar 5.0 5speed that i am finishing up
mike
Title: fuel pressure spec
Post by: jcassity on January 29, 2009, 02:26:33 AM
mustang,tbird,coug,, its all EEC.

The fuel presure what?  you said it was rock steady.


It should drop a little when you apply throttle but recover while holding a steady rpm range.

example,, you work the linkage up to xyz throttle and hold it there.  The fuel pres guage will drop a little then steady out / recover to about 40psi.

Now driving will produce more of a drop when you watch the guage.  I know you didnt say the fuel presure was doing this ,, you are only asking "should" it do it.

I am wondering why you are asking.
Title: fuel pressure spec
Post by: joker77_2005 on January 29, 2009, 10:03:18 AM
well i checked fuel pressure on all my other fords and at idle i have around 32-35 psi of fuel,driving down the road under load with throttle the pressure ramps up to 42-48psi,and under deccel i have 32-35psi.so what makes the old cfi differ for fuel pressure?
btw i wanna say the injecters are a lite green
mike
Title: fuel pressure spec
Post by: jcassity on January 29, 2009, 12:52:29 PM
Now we are getting somewhere...........

Like the color green I show on post 4 or whatever?  Those have never been inside of a 5.0CFI.  You lack fuel delivery by nature of thier flow rate.

Yours should be blue tops, green tops are for v6 cars, uless they are equal to or aftermarket, I cant explain why you have green tops.

Go to my diy link or jump to the thread below.

http://www.foxtbirdcougarforums.com/showthread.php?t=22388&page=3


For your high tps voltage at idle,, remove the tps and use a round or "chainsaw file to oval the holes.  Remount and snug only the screws down. Rotate the tps or adjust it until you dial in .6v - .9v DC.

you having over a volt is not correct but is on the boarder of acceptable limits.

Later CFI units will have a 1/4'' x 1'' long gold elbow fitting near the driver rear cfi mount.  Since we have just discovered yours is the earlier or "first breed" CFI, I can see now why you dont have carbon build up. 

Your CFI and the later verson appeared on 84's so there are two types for that year.  I am starting to wonder if you are EECIII instead of EECIV.
Title: fuel pressure spec
Post by: joker77_2005 on January 29, 2009, 02:22:50 PM
the emission stcker on the fan shroud says eeciv
Title: fuel pressure spec
Post by: joker77_2005 on January 29, 2009, 02:34:27 PM
i see a
eose a1a
0280150900
445
060
ur right up is saying these are the blue top injecters
Title: fuel pressure spec
Post by: softtouch on January 29, 2009, 04:14:34 PM
Came across some interesting verbage in the 84 shop manual.

In the disassembly of the CFI Fuel charging assembly:

"One at a time pull the injectors out of the upper body. Identify each injector as "choke" or "throttle" side".

It refers to a figure with an arrow pointing to the bottom end barrel of the injector and says "injector identification letter"

In the assemble section:

Identify injectors and install them in their appropriate locations (choke or throttle side).

It kind of implies there is some difference between the two. I never thought there was any mechanical difference.

I wonder if the EEC controls them differently, like when cranking for instance.

Maybe you could try reversing the the connectors on them and see if it starts any better.

I read somewhere you can test the injectors by unplugging them one at a time while idling and see if the RPM drops the same amount.
Title: fuel pressure spec
Post by: jcassity on January 29, 2009, 04:36:58 PM
His orintation of the tan / black connectors are correct.

That unplugging an injector shop manual test works better if you have an injector for each cylinder.  you just do the ratio of rpm to qty of injectors.  This means he will have a flipping / flopping motor if he unhooks one.

Here is what i do see / know.  Someone has been all up in that CFI.  That is not a stock FPR unless the freezeplug has been drilled out on top and removed so someone can adjust it.  The shrader valve is not stock either.  That CFI ****I THOUGHT***** was only found on 83 cougs and most all your LTD's of the like back to 82 or 81.

You have a cfi pn on the side, can you put it up?
Title: fuel pressure spec
Post by: jcassity on January 29, 2009, 04:41:57 PM
Is that injector wet?

You can also attemp to flush out any debris on the top side of the injector by removing the shrader valve, ground your eec test conn to chassis, set up to catch gas, turn on your key , let gas flow out. 

There is a square bolt head on the under side per your last pic that can be removed as well to get up in there with a gun brush to clean out those ports as well.


If you can have someone up at the cfi spraying a little gas while you keep her running, and while adding gas by spray bottle and gas pedel she sounds better, then your problem is back to fuel delivery,likely at the injectors.

Those injectors should read about 2ohms there abouts.
Title: fuel pressure spec
Post by: joker77_2005 on January 30, 2009, 12:40:12 AM
the fitting on the shrader valve is for my pressure gauge,as for the injecters being wet i had sprayed them down with carb cleaner to see the color better and they were still wet when i took the pic
i wanna say this thing is flooding out,maybe getting to much fuel
as for when i try to load it up and do a power brake to spin a tire it will bogged down and cut off and wont start unless i put the pedal to the floor
throttle body has --e4ae fb b 4f 13--highlghted with yellow markall paint
mike
Title: fuel pressure spec
Post by: jcassity on January 30, 2009, 11:13:51 AM
ok,, turn down your fuel presure......

your plugs must look wet/like hell.


Now that you think its too much fuel, pull the ACT sendor located on one of the intake runners (I think on the pass side front) and clean it off as well.  Read its resistance per my diy link just to make sure its cold reading is correct.

Set your choke just like you would a carb when the motor is bone cold and the throttle plates barely start to open.
Title: fuel pressure spec
Post by: joker77_2005 on January 31, 2009, 12:31:31 AM
i lowered the pressure to 35psi,choke is good,when cold i pat the gas once and she will start right up.after she gets a lil warm is when the problem starts
that is as far as i got,may look at the o2 sensor and act in the am
mike
Title: fuel pressure spec
Post by: blackcougar71 on January 31, 2009, 09:45:46 PM
all the cfi v8 i have seen  had the plunger/ vacuum thing instead of the throttle position sensor and the v6 had the throttle position sensor.
Title: fuel pressure spec
Post by: jcassity on January 31, 2009, 09:49:32 PM
Quote from: blackcougar71;254703
all the cfi v8 i have messed with have had the plunger/ vacuum thing especially on 83-86 and the v6 had the throttle position sensor. my car when i got it had the blue injectors instead of the green injectors. but i switched to green till i upgraded the fuel system that  went i to two yellow injectors from a 4.6 crown vic.


How does this help out with the problem other than adding to the problem trying to figure out what it is you said.?
Title: fuel pressure spec
Post by: joker77_2005 on February 01, 2009, 07:40:35 AM
yea,i am still trying to comprehend that one
mike
Title: fuel pressure spec
Post by: jcassity on February 01, 2009, 06:19:20 PM
im out of ideas man.............sorry
a fresh set of eyes would be better cause i have no idea what the problem is.  First time ever on here is say it,,, "i give up"
Title: fuel pressure spec
Post by: joker77_2005 on February 01, 2009, 08:26:06 PM
thats cool,imma take all the relpys and read threw to try and get some diff ideas on what it may be
i did find out that the ignition switch itself is about broke in half,it has about fallen apart
mike
Title: fuel pressure spec
Post by: joker77_2005 on February 06, 2009, 02:01:39 PM
little update
i found that the wries going to the ignition mod connecter are bare with no sheilding,i ordered a new one,should have it in a couple days
mike
Title: fuel pressure spec
Post by: joker77_2005 on February 15, 2009, 01:28:22 PM
FiNAL UPDATE
i put a new ignition module on and the ole girl came to life
wow it is amazeing what a old non ho 302 with single 2in exhaust will do
now to get her inspected and start moding her out
mike