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fuel pressure and performance

T

Trimmy

NAXJA Forum User
Location
Rapid City, SD
I decided to test the fp in my 2000 cherokee today because it was taking a while to start up and seems underpowered for only having 32s on it. The truck tested around 30 psi at idle ive read that they need 49 +- 5 could this be my hard start and low power problem?
 
It certainly could be. The spec low is 42. If you're at 30, you have a pretty serious fuel delivery issue. You could verify it with another gauge to be sure that the original gauge is accurate, but if it is the same psi, it is time for a new fuel pump assembly.

Whatever you do, don't buy an Airtex. I specifically look for a Bosch as they are as reliable as the OEM and about $100 cheaper.
 
The fuel pump assembly consists of pump/regulator/filter/level electronics.

That last one is just the pump. You can piece meal the parts if you can find them, but I generally get a new assembly in there and I'm done with it. If you piece meal, you might be back in in a couple of months to replace some other assembly component.
 
yea i need to do something just had the codes pulled I have

-PO303 misfire #3 cylinder possible causes low FP
-PO138 heated 02 sensor bank 1 and 2 possible cause low fuel pressure(and previous owner cut the cat off)
-PO171 fuel trim bank 1 possible cause is low FP as well.
 
yea thats what im doing I found a write up on replacing the stock intank pump and the regulator/filter and thats what im doing I'm hoping it will cure the problem.
 
My fuel pump went lazy like yours before. The power difference, especially at higher rpm's, after the new pump was insane. I don't remember what brand I bought, but it was from napa and I opted for just the pump rather than the assembly. It was easy to swap and reuse the old assembly onto the new pump so it was way worth the price difference. The new pump is LOUD, but it's been performing great for 3 years now so I can't complain. And I have a remote starter so I get to hear my jeep start up from outside the jeep and I still grin when I hear my pump go RRRREEEEEEEAAAARRRR, just before it fires up :D
 
Oh, and you should look into throwing a check valve on the line just off of the pump assembly since you have a 2000. I've heard that on the 96+'s, you can't use the BMW check valve directly on the fuel rail or it will cause excess pressure and other bad stuff. But I don't see why adding one all the way back at the pump would cause any issues. The stock valve is weak sauce.
 
Well if your gonna replace the fuel pump for the love of god please do not get an airtex. I went through 3 of them before I went and got a bosche one from Napa. It costs a bit more but worth it IMO since I dont have to drop my friggen tank again now.
 
I bought the OEM pump off of mike on EBAY. I have read a lot threads on the pump and a lot of guys recommend him and his pump. I only paid 153 shipped for a new pump, grommet, tank seal, filters, and a new regulator/filter. it should be here friday or saturday at the latest and I really hope it does help a lot. I know im tired of the hard starts lol...
 
sam24th said:
Well if your gonna replace the fuel pump for the love of god please do not get an airtex. I went through 3 of them before I went and got a bosche one from Napa. It costs a bit more but worth it IMO since I dont have to drop my friggen tank again now.
Click to expand...

Truer words have never been printed. Can't tell you how many threads I've answered with Airtex fuel pump owners that have been sorely disappointed. Some ebay stuff is crap too. I go Bosch. Worth every penny......
 
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