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OK, this one is tuff...... No codes. 96 Bird, about 128K on the clock. 4.6L

Engine intermittently starts real hard. Continuous cranking seems to be only thing that starts it....then it runs rough for 15-20 second and smooths out....to run/start fine after......no loss of power, purrs fine....

Car was driven this morning a 6am (started fine after sitting out in cold all night) , and went out to start it about 4pm and it failed. No prob's yesterday.......

While cranking today, occasionally get a plug or two firing, and today, smelled a little rich....but my daughter said she had pushed the gas pedal down......

I eventually just cranked it for 20-25+ seconds and it fired...and sputtered to life.

Dug thru the diag procedures and the IAC comes up a lot..... but I've never seen this....so don't know exactly what is going on. I know the IAC is to richen when cold...then lean out once the injectors take over. Just can't tell if the plugs are fouling out yet....or very very lean.......

I would think if IAC failed rich, that the O2 sensors would be screaming "rich!" and we'd see a code.

I may have an IAC from an old intake.....but I may have trashed it......and I don't know if I have a new gasket.

Can IAC gaskets be purchased new by the piece?

There is a procedure to test the IAC by having it cold, then heating with a heat gun to see if the plunger moves when warm..... so was thinking of trying this....

If the wiring was toast (open wires or shorted) we'd see a code too. But no luck there.

One last section recommend trying to start car with accelerator depressed half way or so. If it starts then, things really start to point to the IAC and or circuits. But no codes tends to make me think this is a mechanical issue of sorts.

I had thought (read guessed!) it seemed like the keep alive mem was going funky.....but I see that this is wired directly to the battery..... thinking that the computer had to relearn the running profile......don't think that is the case now....

I replaced the ignition switch thinking it was supply voltage to one of the relay circuits....but that was a bum shot.... (shotgunning is a bugger on these cars!)

Any help is appreciated!
Steve
 

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fuel pump losing its prime maybe?
Agree check fuel pressure
Key on engine off 35-45 psi
Idle w vacuum 30-45
Idle w/o vacuum 40-50
Holding pressure after 5 minutes 30-40
Max pressure 65

I'm pretty sure these are accurate but if you have a manual you may want to double check considering I've had beer since the last time I redid my fuel system.
 

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There have been a lot of cars over the last year or so needing fuel pump replacement; my 97 was one of them.

The fuel pressure checks blue95lx recommended are where I'd start.

Most likely, you will see the pressure bleed off after you turn the key off; and it takes a while to come up while cranking.
 

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Most likely, you will see the pressure bleed off after you turn the key off; and it takes a while to come up while cranking.
Thinking the same thing. I'm in the process of a complete rebuild this year and before the body went out for paint I realized when I'd turn the key it would start at 38-40 psi and drop drastically to 18 and bleed down slowly to darn near zero.

Ended up being the vacuum hose to and the fuel pressure reg but I had a new pump, sending unit and filter sitting in the trunk. Before disassembly I put it all in and she's holding steady around 40 psi

No check engine light
 

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yep, that would have been my guess.

usually what works for this problem as well is keying on the car a couple of times before trying to start, runs the fuel pump through its prime cycle a few times and builds the pressure needed to start easy.

i would also make sure you change your fuel filter if its an unknown when it was serviced last.
 

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Discussion Starter #7
Good Fuel Pump Gauge?

OK, thanks for the re-direction! Never would have gone there right away, but you guys seem to be running the same path... and easy enough to test....

I have an old school Vac/Fuel pump guage, but that won't handle 40psi+! To use it would be a scary thought.....! Also have a compression tester which would handle pressure, but not sure about using it on fuel!

Can any one recommend a good tester that is well built and has all the proper fittings? I like OTC and good ol' Rotunda/Motorcraft tools when I can get them, as they are well built, (even if built off shore) and I can see the future of having this gauge around! (Also have a FI F150 with 140K miles and Mazda3....so potential re-use is high!)

I'll also look into Orielly's and see if they rent the testers...may be the quick thing to do while I can then relax and search for another good new one to have on the shelf as "insurance!"

Thanks again!
Steve
 

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Orielly will have a tester for about 45 bux. Having worked for each of the big 3 parts houses I'm pretty sure they don't rent them anymore. The pressure tester should come with the fitting for the schrader valve. If not they'll have one in the help parts aisle down buy the generic fuel lines.

They usually have them behind the counter btw so go straight up to the counter. It'll save you some time and money as opposed to walking through the store looking for it and loading up a basket with stuff you don't need :)
 

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Discussion Starter #9
Have tester...no love!

Update:

Received an OTC fuel system tester that I picked up at a reasonable price and it works well!

So does the car.....unfortunately!

Here is what I found.

With zero pressure on the manifold, the first Key On test resulted in an 8psi reading.

Second time key off, key on, it jumps up to 39 or so. Pump cycles on and off for a very brief time....probably not allowing full pressure build up.

Idle with vac= 32 (30-45 desired)
Idle with no vac= 42 (40-50)
5 minute leakdown= 40 (30-40)
Max of 65 was never seen.
Leakdown 40 min= 19, 50 min=11
Final leakdown after 1 hour saw 7psi.

SO, looks like fuel pump is working as it should........this time.

Will need to wait for next failure.....ugh!

Steve
 

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try cleaning the grounds for the ccrm, worked for me when I was having intermittent fuel pressure problems.
 

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SO, looks like fuel pump is working as it should........this time.

Will need to wait for next failure.....ugh!

Steve
That is a perfect description of a bad fuel pump.

If it was the regulator, it would be running fuel out the vacuum fitting...
 
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