Cherokee XJ Fuel Pump Issues

[Srikumar]

On my XJ, for the past 3 years my fuel pump was always on the weaker side as the engine would fire only on the second crank and never on the first one. However it never was on top priority as the car was performing well. But over the past several months I have found the car to be increasingly sluggish. Recently, when I checked I found that the fuel pressure was dropping to about 40 psi as the RPM was being increased to beyond 3500. As per spec, the fuel pressure should be 49 psi. My questions are :

1. Is such a drop in pressure normal? Does it warrant a change of pump?

2.The original Mopar complete module costs about AED 1450 + vat. I have seen some good reviews of Bosch and Carter but not 100% sure. 

Any feedback or suggestions?

 

[Frederic]

17 minutes ago, Srikumar said:

On my XJ, for the past 3 years my fuel pump was always on the weaker side as the engine would fire only on the second crank and never on the first one. However it never was on top priority as the car was performing well. But over the past several months I have found the car to be increasingly sluggish. Recently, when I checked I found that the fuel pressure was dropping to about 40 psi as the RPM was being increased to beyond 3500. As per spec, the fuel pressure should be 49 psi. My questions are :

1. Is such a drop in pressure normal? Does it warrant a change of pump?

2.The original Mopar complete module costs about AED 1450 + vat. I have seen some good reviews of Bosch and Carter but not 100% sure. 

Any feedback or suggestions?

 

Hey Buddy,

I just checked on some Jeep forums and indeed they speak about 48psi with 5psi plus or minus being acceptable. The issue could be related to the check valve:

https://www.jeepforum.com/forum/f11/looking-specific-fuel-pressure-readings-01-4-0l-632854/

I remember removing my fuel pump once and noticed that there was a small filter mesh bag on the suction side that was slightly clogged. I cleaned it up but did not notice anything different. Maybe your pump has a similar filter mesh and could be more clogged ? In that case that could explain the lower pressure.

 

[sertac]

I changed on my old Cherokee and now on my Grand Cherokee also fuel pump is weak. When the fuel level lower than quarter when i am turning right if i give gas it is losing power. I start thinking fuel pump one of the weakest point of these cars. 

[Srikumar]

25 minutes ago, Frederic said:

Hey Buddy,

I just checked on some Jeep forums and indeed they speak about 48psi with 5psi plus or minus being acceptable. The issue could be related to the check valve:

https://www.jeepforum.com/forum/f11/looking-specific-fuel-pressure-readings-01-4-0l-632854/

I remember removing my fuel pump once and noticed that there was a small filter mesh bag on the suction side that was slightly clogged. I cleaned it up but did not notice anything different. Maybe your pump has a similar filter mesh and could be more clogged ? In that case that could explain the lower pressure.

 

I suspect that as well, but the car starting in second crank does indicate the check valve, and I am not sure who has the expertise to replace that part. 

 

@sertac did you change it with Mopar or any other brand?

[desertdude]

If after 10-20 minutes after switching off the car the fuel pressure falls dramatically then your check valve is toast.

And also if your pump is excessively noisy then it means it's also about to die. That is if you can hear a distinct buzzing from it after you turn it on without starting the car.

Also the mesh as mentioned specially for desert cars get very Sandy and clogged up. 

[sertac]

2 hours ago, Srikumar said:

I suspect that as well, but the car starting in second crank does indicate the check valve, and I am not sure who has the expertise to replace that part. 

 

@sertac did you change it with Mopar or any other brand?

I used mopar and it performed perfectly after. Now with this car i will change the filter first to see if any clogging issue causing that problem. If filter wont solve it i will go with the Bosch or any other brand. Mopar one is expensive. 

[Srikumar]

1 hour ago, desertdude said:

If after 10-20 minutes after switching off the car the fuel pressure falls dramatically then your check valve is toast.

And also if your pump is excessively noisy then it means it's also about to die. That is if you can hear a distinct buzzing from it after you turn it on without starting the car.

Also the mesh as mentioned specially for desert cars get very Sandy and clogged up. 

Would you know if the check valve can be fixed or the whole unit needs to be replaced. Also would a bad check valve result in power loss at higher rpm, or does that issue point towards a clogged mesh.

[desertdude]

14 minutes ago, Srikumar said:

Would you know if the check valve can be fixed or the whole unit needs to be replaced. Also would a bad check valve result in power loss at higher rpm, or does that issue point towards a clogged mesh.

I dunno about being able to repair it. You can start by checking the fuel filter also to see if it's clogged.

As for the mesh it's not worth the hassle to open the tank, clean it out it back and then see if it makes a difference.

My theory is while you are in someplace difficult to get to. Might as well change everything, unless you just replaced it.

Example: if you are opening the transmission to change the clutch plate might as well change the pressure plate as well as release bearings.

Instead of 6 months or a year down the line you realize you have to bring the transmission again to change the bearing.

Whole your are at it get it done.