LooneyTech
Red Skull Member
- Joined
- May 19, 2020
- Member Number
- 281
- Messages
- 8
... yeah, that !
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Anyone ever had a weak fuel pump? - SOLVED
- Thread starter Fuzzydog
- Start date
... yeah, that !
SanDiegoCJ
Non-Lemming
I had a similar problem on my 2006 Jeep LJ with the 4.0L I6. The fuel pump was dying and putting out low pressure.
The other problem a system like that can have is the regulator going bad.
TrailTamer
🤣🖕🏻
Fuel pressure testers usually have that valve below the gauge.
Use it to test the pump…. To test pump’s flow rate.
Run the tube into a bucket, bonfire, or something.
Engine running, push in the button to ‘bypass’ the gas and see whether engine continue to idle with this large ‘leak’, which it should, and the pressure shouldn’t take a dive.
Use it to test the pump…. To test pump’s flow rate.
Run the tube into a bucket, bonfire, or something.
Engine running, push in the button to ‘bypass’ the gas and see whether engine continue to idle with this large ‘leak’, which it should, and the pressure shouldn’t take a dive.
TOMS97ZJ
What?
Just helped my friend replace the pump on his ZJ.
It would prime for a few seconds then just stop pumping.
If it sat for a day it could idle for a long time off the initial pressure but that’s it. Pump was only a year old too.
It would prime for a few seconds then just stop pumping.
If it sat for a day it could idle for a long time off the initial pressure but that’s it. Pump was only a year old too.
Fuzzydog
Red Skull Member
Yeah it has that on my tester. Will try that out, 👍
Fuzzydog
Red Skull Member
So yesterday, jeep has been sitting flat overnight, starts right up, revs great, 50psi fuel pressure. I drive fwd about 10 ft and ramp the right front up on a bank and PFT - stumbles and dies, fuel pressure down to zero. Excellent, it IS the fuel pump.
Roll it back to flat, crank crank, won't start, no fuel pressure. Get the tools out to start the fp replacement, but the intermittent fp still bothers me. So I have a closer look at the harness where the fp pigtail plugs in. Seems tight, can't pull it apart and very little movement between the 2 plugs, red locking pin is in place. But after messing with it, it does start. While it's running, I can make it stumble and then smooth out by wiggling and tugging on the harness.
I dig deeper and it turns out that the plug was not fully seated. At first I could not push it in any further, but after plugging/unplugging a few times suddenly CLICK! and it went in a bit further.
Test drive confirmed no more issues.
And now I have a fuel pump on the shelf ready for when it actually does go. I will do the swap in about another 50k kms as this thing still has low mileage.
Thanks for all that offered advice - it did help in the diagnosis.
Roll it back to flat, crank crank, won't start, no fuel pressure. Get the tools out to start the fp replacement, but the intermittent fp still bothers me. So I have a closer look at the harness where the fp pigtail plugs in. Seems tight, can't pull it apart and very little movement between the 2 plugs, red locking pin is in place. But after messing with it, it does start. While it's running, I can make it stumble and then smooth out by wiggling and tugging on the harness.
I dig deeper and it turns out that the plug was not fully seated. At first I could not push it in any further, but after plugging/unplugging a few times suddenly CLICK! and it went in a bit further.
Test drive confirmed no more issues.
And now I have a fuel pump on the shelf ready for when it actually does go. I will do the swap in about another 50k kms as this thing still has low mileage.
Thanks for all that offered advice - it did help in the diagnosis.