Finally No Start

Reply #60 – June 19, 2012, 06:05:50 PM

Quote from: dw85745;392760

Soul:

Yep: But based on previous thread both pressure and volume on supply side look OK,

Let me see if I can conceptually clarify this pressure regulator thing.
If the fuel pump was only capable of 39psi of pressure, the regulator valve would never open and there would be no return fuel flow.
If the pump is capable of more than 39psi, it forces the regulator valve open and some fuel returns to the tank.
How wide does the regulator valve open? It depends on how much more than 39psi the pump is capable of.

Finally No Start

Reply #61 – June 19, 2012, 10:12:38 PM

Softtouch regarding:

Quote

If the fuel pump was only capable of 39psi of pressure, the regulator valve would never open and there would be no return fuel flow.

Makes logical sense.

Quote

If the pump is capable of more than 39psi, it forces the regulator valve open and some fuel returns to the tank.

Again logical - but - How this pressure correlates to the volume that is pushed through the regulator is the question (at least for me)?
Per the shop the return line is supposed to put out a volume of 9.5 oz at 39 psi.
So if it is less (volume that is), does that mean there is something wrong???
-- or --
Is the pump pushing just air (> 39 psi) and no gas?
There is probably some math formula (my guess in area of fluid dynamics) but will have to search net.

Quote

How wide does the regulator valve open? It depends on how much more than 39psi the pump is capable of.

This I'm not sure of, My guess is that with any pressure > 39psi, the diaphram and spring in the regulator that controls (limits) the pressure
to 39 psi, would reach its design point (here 39 psi) and any additional pressure (and volume) would be routed through the return line orfice of the regulator
instead of through the orfice to the injectors.

///////////// FollowUP //////////////////
Worth a read:

http://www.kennebell.net/KBWebsite/Common/pdfs/BAPtheory_kens.pdf

Finally No Start

Reply #62 – June 19, 2012, 11:40:17 PM

Volukm and pressure are different, and don't match each other.

Think about 120 psi in a squirt gun, then 120 psi in a garden hose. One move much more liquid.

Where you have 39 psi at idel, i. Don't think the pressure is the problem. It doesn't take 9oz of fuel to run a car for 10 seconds.

Going back to the starting fluid,

I ran my car out of gas. The guage didn't work, and the wife cleared the trip computer so I wouldn't know how mmuch she drove the car. I thought the fuel pump died. I tried starting fluid after checking some other things, and it fired right up, with no problems. Half a gallon of lawn mower gas got me to the gas station, and I wasted $90 because I was on the freeway and couldn'kt leave it.

If it won't start on starting fluid, its not gas related.

Finally No Start

Reply #63 – June 20, 2012, 08:25:58 AM

Haystack:

Re:

Quote

Volukm and pressure are different, and don't match each other.

Think about 120 psi in a squirt gun, then 120 psi in a garden hose. One move much more liquid.

Where you have 39 psi at idel, i. Don't think the pressure is the problem. It doesn't take 9oz of fuel to run a car for 10 seconds.

Hose and Squirt gun good buttstuffogy.
That's why -- IMO -- shop has two separate tests.
On the volume side they must "think" 9.5 oz on the return side is of importance or why call it out as a spec {see shop p24-35-5} ?

Quote

Going back to the starting fluid,

Interesting. In my case I let car sit overnight with both the fuel injector harness disconnected as well as the fuel pump relay - so - the only gas was the starting fluid.
You can tell it wants to start -- just doesn't.

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Before messing with the CFI, I think I'm going to pull all plugs again. Then attach them to the plug wires and crank to see if I'm getting spark at all cylinders.
I also may try and redo compression test and make sure dissy is ot TDC.
That - IMO - should eliminate any questions on spark and compression.

Finally No Start

Reply #64 – June 20, 2012, 01:28:31 PM

Does that engine have a TFI module? if not, disregard my post...but if it does, try a known good one, and let us know the changes (if any)

Finally No Start

Reply #65 – June 20, 2012, 01:33:23 PM

Thundersport302

will do, but will have to be this weekend. AFAIK, if you get spark at the plugs, this eliminates the TFI and PIP.

Finally No Start

Reply #66 – June 20, 2012, 01:53:00 PM

Once again if you have fuel
Spark and compression it will start

Another thing is the exhaust CLOGGED??? At this point anything is possible. But you compression numbers are in the DUMPS. Very low. Min is app 135-140.

Finally No Start

Reply #67 – June 20, 2012, 02:26:46 PM

Quote from: dw85745;392854

Thundersport302

will do, but will have to be this weekend. AFAIK, if you get spark at the plugs, this eliminates the TFI and PIP.

My mustang had a piss-yellow spark at the plugs, wouldn't start. swapped in a different TFI, and it started. Ran like , but that was another issue that's not relevant to this thread. Remember, your TFI DOES affect your spark output....if it's weak or deadd, you'll get weak to no spark.

Finally No Start

Reply #68 – June 20, 2012, 07:58:55 PM

Your car will still run with low compression. My old 86 5.0 with 235k miles or so ran at 110-125 psi with onne cylinder hitting 90psi, and would spin a tire up till about 40mph from a dead stop. but that doesn't mean it will run well. By the time I got to 290k, it was barely running.

Finally No Start

Reply #69 – June 20, 2012, 09:50:52 PM

Quote from: Haystack;392906

Your car will still run with low compression.

Not always , I just dealt with a 79 f250 that would not run at all , a compression test revealed a max of 75lbs on two cylinders...those were the "good" two

Finally No Start

Reply #70 – July 09, 2012, 10:53:45 PM

Thought I'd do an update:

1) Swapped TFI and till No-Start.
2) Decided to rebuild Throttle body and have injectors tested.
Have TB cleaned and injectors out, but still need to have them tested.
Injector screens look clean.
3) Just noticed a couple of wires where insulation has come off near connector.
So this needs some liquid tape.
4) Haven't got around to pumping some gas yet to check for water in tank.
As noted -- believe this thread -- replaced fuel filter with low mileage on it (around 2000)
to see if any trash or rust. Nothing wrong with filter.
5) Just noticed tranny front pump seal is leaking a bit.

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Kinda reaching a point - my age that is -- of all the little fixes.
Hate to do it, as love this car, but looking into getting rid of the Cougar.
Thought I'd never say that.
Since original owner have a detailed parts history.
Can get $400 - $500 from the metal guy here, but would like to see bird go to a good home, even if just for parts.
Anyone near Tucson, and need a bird with a lot of new parts let me know via this thread and we'll see what we can work out.