Help please. (Fuel or exhaust problem?)

jake_black94

jake_black94

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Been searching the forums for the past couple days, can't really come up with anything that I haven't tried - was wondering if one of you experts could point me in the right direction.

I've been fighting a hard-starting condition on my '94 for a couple months now. First start of the day takes at least 5 seconds of cranking before it catches; at the worst, it requires waiting a moment and turning the key again. When it does catch, it's rough for the first couple seconds. Later settles down and idles fine ~750RPM.

It's quite driveable on the street - handles WOT fine, even. Highway cruising, though, is where the second problem starts. After cruising for about 10 minutes, I've been getting an intermittent CEL - comes on, goes off, seemingly at random. After this starts to happen though, it's nearly impossible to surpass ~3250RPM.

Already: cleaned MAF, replaced plugs, wires, fuel filter, and Camshaft Position Sensor. I'm going to test the fuel pressure at the rail tomorrow, but does this sound like a fuel pump/pressure regulator, or possibly a bad catalytic converter? Those are my only two thoughts.

Car is all stock (save for K&N filter and air silencer removal.) About 89,000 miles.

Thanks guys.
-Jake
 
jake_black94 said:
Been searching the forums for the past couple days, can't really come up with anything that I haven't tried - was wondering if one of you experts could point me in the right direction.

I've been fighting a hard-starting condition on my '94 for a couple months now. First start of the day takes at least 5 seconds of cranking before it catches; at the worst, it requires waiting a moment and turning the key again. When it does catch, it's rough for the first couple seconds. Later settles down and idles fine ~750RPM.

It's quite driveable on the street - handles WOT fine, even. Highway cruising, though, is where the second problem starts. After cruising for about 10 minutes, I've been getting an intermittent CEL - comes on, goes off, seemingly at random. After this starts to happen though, it's nearly impossible to surpass ~3250RPM.

Already: cleaned MAF, replaced plugs, wires, fuel filter, and Camshaft Position Sensor. I'm going to test the fuel pressure at the rail tomorrow, but does this sound like a fuel pump/pressure regulator, or possibly a bad catalytic converter? Those are my only two thoughts.

Car is all stock (save for K&N filter and air silencer removal.) About 89,000 miles.

Thanks guys.
-Jake
Click to expand...

Im not sure but maybe an IAC? Gen1 is PITA and they do go bad!
 
so did you check to see what the code was?
or are you blindly throwing parts at the car?

guessing, you might need O2 sensors, and you might need a fuel pump.




on a cold start,
key on, 1 2 3, key off, key on, 1 2 3, key off. key on, 1 2 3, key off ..... this primes the fuel system.
does it start any better?
 
Chris, that does help it. That's why I'm thinking fuel pump.

I'm trying to avoid blindly throwing parts at it - I have at least been doing research regarding the symptoms I'm getting. I've not been able to check codes, though, as the CEL turns off when I bring the car to a stop each time. OBD1 wouldn't have a store codes, would it?
 
Last edited:
jake_black94 said:
OBD1 wouldn't have a store codes, would it?
Click to expand...

yes. it does. you need a paper clip.

http://www.troublecodes.net/Ford/

ford-analog-voltmeter.jpg


use the bottom diagram for hooking up the jumper wire.

your car will output 3 digit codes.
 
Alright, I wasn't aware it stored them... thought that was an OBD-II feature only. Thanks.
 
if you're thinking fuel_pump, you can check it by filling up your tank...that's when they like to die
:joke
 
You can rule out O2 simply because its ignored on a cold start. As mentioned, IAC, TPS (throttle position sensor) or if custom programed, a problem there. Although dump the K&N filter. They are crap and have taken out a few good MAFs. Even when cleaned, a MAF once coated with oil can easily be toasted for good.

And then there is always the vacuum leak problem. Check you intake tube to throttle body. A known location for leaks. Its a sneaky thing to get on just right once off.
 
besides, the O2 sensors affect the fuel trims. and the fuel trims are used in startup and wot. so they are not exactly "ignored" at all.
 
The long crank time is probably a weak fuel pump. I agree also that most likely 1 or both o2's are bad. In my experience obd 1 only stores the codes about half the time. But don't rule out plugged cats, as they can cause those symptoms also. If you check fuel pressure, check it both ways, unplug the vacuum to the pressure regulator and see if the pump can increase the pressure 8 to 10 pounds. Even if it can it still could be weak though.
 
You can get 2 Motorcraft 02's for fairly cheap on rockauto. Much cheaper than anyone else near you will have them for, unless something has changed since I bought two. I would change the fuel filter to eliminate that first. Almost sounds like a weak pump though to me. Then again, sounds like 02's too, in some ways. TPS and IAC are never a bad buy to know that worry won't be there for years to come. I would try and get this stuff little by little if you plan on keeping it because it will one day be needed and usually when you least expect it.
 
I was sorta joking before, but seriously...if you plant to r/r fuel pump, do it when your tank is almost empty. Over and over I've read where it dies on a full tank. That's how mine went out earlier this year. It's a real MF trying to siphon this tank empty.
 
Ran the codes - looks like O2s are the culprit indeed. Thanks for the advice, guys. Any memorable/decent replacement writeups? I've heard they're a pain on these cars.
 
jake_black94 said:
Ran the codes - looks like O2s are the culprit indeed. Thanks for the advice, guys. Any memorable/decent replacement writeups? I've heard they're a pain on these cars.
Click to expand...

Honestly I didn't see where they were so hard but I had the front end jacked up real high and gave myself enough room to move around. I bought the ones with the 10" wire but they could have been shorter. Once jacked up, I might have had under 15 min per side involved. Wasn't bad at all. I'd rather change both of those than to do an IAC or TPS but that's just me.
 
chris2523 said:
besides, the O2 sensors affect the fuel trims. and the fuel trims are used in startup and wot. so they are not exactly "ignored" at all.
Click to expand...

Must be an ODBI thing then, in ODBII they are not utilized for cold start. Instead the car runs in open loop until the sensor reaches operating temp. Which is fairly quick since they are heated. I did a lot of programing for the Mark VIII, but mine was ODBII.
 
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