ThE_CaPtaIn

I have a 2001 jeep Cherokee with a 4.5in lift 31in tires stock gears it has the neon injectors and bored tb. I drove it for the longest time. (at least 6months) without a check engine light after Doin the injectors and tb. Now I have a check engine light on or a few weeks went and pulled the codes today had a random misfire code a cyl1 misfire code cyl 2 misfire code and another code that said fuel press low leak or mechanical failure. I'm getting very poor fuel mileage around 9 or 10. And on a occasion I will go into limp mode won't rev over about 2500rpm and the check engine light will flash. I went by the parts store and picked up a coil pack and a fuel pump. I have looked everywhere for a fuel leak and haven't seen Anything... I have checked from fuel rail to fuel pump and no signs of a leak. But the jeep runs fine. I also fired the jeep up and at idle pressed in the the test port valve on the fuel rail and it never missed a beat... I know that wasn't applying a load... But it seemed to have good pressure I don't have a fuel press Gauge to read actual fuel press... I was just hoping to get some opinions b4 installing the parts.

tjwalker

For your 2001, you need 49 psi, plus or minus 5 psi for the engine to operate properly. This testing must be done with a gauge; no shortcuts allowed. Some parts stores will rent you this gauge inexpensively; call around.

All symptoms and codes point to a possible fuel delivery problem.

I always recommend testing before replacing parts. But if you have the fuel pump assembly and choose not to test, you could roll the dice and put it in. Hope the pump is NOT an Airtex!

ThE_CaPtaIn

Lol it is an airtex. Are those bad? I run one in my Cherokee buggy and it's been fine... It was what they had on the shelf at oreily... And I will run and get a pressure gauge.

ThE_CaPtaIn

Got me a pressure test gauge has 50 psi a idle I can press the button to dump fuel out the line it doesn't stubble at all but the pressure drops to about 15... But I'm assuming that is normal. So I'm guess it's not the pump???

tjwalker

If you are at 50 psi at idle, you are well within spec for fuel pressure. On occasion, some fuel pumps suffer from lack of "volume" output and not pressure, so the fuel pump is still a possibility, but more of an outside chance.

If you could post the EXACT code numbers here, we could possibly help you more. With OBD codes, the devil is definitely in the details. Codes are not always straight forward to interpret, but absolutely invaluable in determining root cause of problems.

ThE_CaPtaIn

Ok I will have to go back to the parts store tomorrow And pull the codes again. And I don't think it is a volume issue cuz The fuel gauge has a button allowing you to dump the fuel while the engine is running which I did and with the button pressed I put about a half gallon of fuel in a bucket And it never missed or sputtered... But I will def get those codes asap. And post back.

rrich

Fuel pressure problems are not selective - cannot affect only 1 and 2.

Check plugs.

ThE_CaPtaIn

There was also a random misfire code as well. But the codes where cleared when I disconnected the battery. The misfire codes did not come back but the reoccurring fuel pressure code did. This is exactly as it read on the code reader.

P1494 leak detection pump pressure switch or mechanical fault

The code reader I used also takes a snap shot of different engine parameters. This code took place at idle upon start up. Any help would be appreciated!

rrich

I'm wondering HOW you cleared the codes. Disconnecting the battery for a few moments clears the volatile memory,but not the deep memory. You have to disconnect the battery for AT LEAST 8 hours to clear it.
There are lots of short-cut schemes around - flashing lights, stepping on brake pedal, sitting under a pyramid hat, killing a sheep at midnight etc - they do not clear the deep memory. NONE WORK - They just clear the surface memory.
The fuel pressure code may be coming from the deep memory. Could be a fluke, but will keep coming back till it's erased.
Let us know.

cf1k1

If I'm remembering correctly, and I think I am, it has to do with the fuel pressure in the entire system. I had the same code forever. A brand new $7 gas cap fixed it.

ThE_CaPtaIn

I disconnected both battery terminals and touched them together for about 2 hrs and when I put them back on the CEL was off. But came back on after about 20miles. And ok I will get a new gas cap and give that a shot. But I think there is another issue.... Cuz it has a hard starting issue... And if I cycle the key a few times it dosent do it... It's like the fuel is draining outta the line when it sits.... Is there a check valve somewhere in the fuel system to hold prime in the line?

rrich

If you had a data link to a laptop you would be able to see the way you did it DOES NOTHING except clear the surface codes like a 1 minute disconnect does.
Touching cables together does nothing either.
scanners won't either - except the dealer's DRB
It's no more effective than wishing or doing a rain dance.
DEEP CLEANING is what's needed.

8 hours, preferably 12 disconnected allows the capacitors deep in the computer to discharge. They are protected by diodes - that's why other methods DO NOT WORK.

the quickie ways are an internet rumor = BULL! They clear the CEL and codes temporarily, but they will come back.



If that doesn't help, especially since it's hard to start sometimes - I've found the following:
replacement fuel pumps - especially Airtex - use a cheapie fuel line on the pump itself. They don't use fuel line, but vacuum hose. It deteriorates in the fuel.
Remove the pump - look at the short piece of hose on it - the cheapies get soft and leak. Simply replace that little piece with a quality fuel line - about 50 cents..
SYMPTOM - codes, hard to start, starves and dies out on hard right turns when the tank is low.

ThE_CaPtaIn

I was attempting to clear the code by disconnecting the battery I just did it out of habit. But I purchased a new gas cap and I also have had the battery disconnected for over 24hrs. I am about to pull the fuel pump and check the piece of hose u were referring to. Thank you for advice.

ThE_CaPtaIn

Ok I dropped the tank and it does not have the same style of fuel pump I purchased... The pump is diff than the one in my older model cherokee I could disassemble the top plastic piece from the lower metal piece which houses the pump. I tried toget it out but the only way to get it out is to cut pastic rivets on TE bottom and I don't believe that isthe proper way. I think it is meant to be changed out as a whole unit. Also there is no fuel hoes it uses a big spring to hold the upper part on to pump outlet. Any ideas? Should I replace the whole unit?

rrich

OOOPS - Sorry - I wasn't thinking - I saw it's a 2001, but didn't think. The pump is different, and lots of work dropping the tank to get to it. Sorry!
intermittant misfire codes, fuel pressure codes, bad mileage - strange.

pressure is good

Did you get the coil pack installed yet?
Still getting the codes?

A shot in the dark - sometimes a plugged exhaust sets all kinds of strange codes - and makes for poor mileage.
Have someone rev it while you listen at the back. Sound normal?
connect a vacuum gauge to manifold vacuum, low?
rev it and hold it up - low?
should be about 15 inches