Yet another slow start thread

2001 XJ

I had a slow start condition and then changed out the battery (unrelated) at which point it started to throw misfire codes (cyl 3,4,5,6 varies between code clearing - typically 3 and 6 for certain).

Changed the plugs (OEM spec and gap), same thing.

Changed the CPS, codes went away but still slow start and seems to be getting worse.

Fuel pump? Coil rail?

Only fuel related symptom I can see is that it won't start from cold till the fuel gauge fully registers whatever fuel level is in the tank. Fuel pump or red herring?

Changing the coil rail is easy enough but a bit of money. Changing the pump is a PITA and I'd rather not do it if I can avoid it (I'm spinning the wrenches).

I was thinking about being pro-active and changing out the injectors for some new balanced ones. Are the injectors a possible source for this problem? That might bump up the priority on that mod.

TIA

Anyone?

I've changed the CPS (Crank) and the coil rail.

I don't seem to be getting the various combinations of P0300, P0303, P0304, P0305, P0306 any more.

Still slow to start though.

I am getting a strong smell of unburnt gas out the tail pipe.

Injectors?

Milage?

Never havent heard of an 01 as new as it is, needing injectors already....then again if you have a ton of miles on it.

could this be any of what you're experiencing?

http://www.naxja.org/forum/showthread.php?t=104266

It has ~100k miles.

I don't think the TSB in that thread applies as this happens when the engine is cold.

You maybe losing fuel presser when keyoff. The fuel rail should matain presser even when off. Else you will crank untill presser rebuilds. Bad reg bad injector(s) most likely. Check presser on rail sometime after keyoff.

That sounds plausible.

Bad what and/or bad injectors?

Ideas on how to troubleshoot? How do I check the rail pressure and the injectors?

Also check for external leaks.
Bad O-rings on injectors was common for some years.
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Bad what and/or bad injectors?
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Bad fuel presser regulator

1. Check system voltage at idle. The dash volt meter is fine. Voltage OK next step 2. Else fix voltage problem.
2. On fuel rail at front of engine is something that looks like a tire value. On this install a suitable fuel presser gauge for high presser fuel injection engine. Run engine and check fuel presser. Rev engine a bit as watching gauge. Running fuel presser up to spec step 3. If presser is low it could be a clogged prefilter (on pump in tank for some years) bad pump bad regulator
3. Running presser OK. LEAVE as is just keyoff. Go inside have a beer watch the game. I hate just standing around. After a bit with key still off check fuel gauge. Presser should be up. If not bad regulator or injector(s) slowly letting the presser leak off. LUCK

Thanks!

Off to buy the gauge at lunch...

Gauge not cheep can you bum one.

badron said:

Gauge not cheep can you bum one.

Click to expand...

~$50 at Canadian Tire. I'll be using it again in the future so I don't mind buying it.

The fuel pressure bleeds off in a matter of minutes.

I was going to do the test for checking whether it is the fuel pressure regulator or the injectors but I can't seem to figure out a way to get the test apparatus to connect to the fuel rail.

Do I need a special tool to remove the fuel line from the rail once the retention clip is off? [2001 XJ] I tried a little gentle pulling but it seems like there might be another "latch" inside the fitting holding it on? If it's a special tool, is this a commonly available thing or D-C only?

How do I adapt a connector to the fuel rail so that I can hook up the test apparatus? I guess an old fuel line or does the port on the fuel rail resemble a normal barb style fitting?

Maybe I should assume that the regulator is the issue and replace it? I have not seen any gas in the oil. The pressure gauge loses about 10 psi per minute or so. If it was leaking that much wouldn't I see hints of gas in the oil from when the Jeep is parked over night?

TIA