Afpr changing pressure?

[lil corb]

Next time you see the pressure dropping, go back there and see it the wires are hot. If so, try changing the ground location.

Good idea Keith, I'll do that and update everyone.

Thanks

 

[92awddsm]

Good idea Keith, I'll do that and update everyone.

Thanks

Also, check the fuel vent/vapor lines and make sure it isn't blocked. If so, you could be pulling a vacuum on the tank which could cause fluctuations.

 

[lil corb]

Also, check the fuel vent/vapor lines and make sure it isn't blocked. If so, you could be pulling a vacuum on the tank which could cause fluctuations.

That's a good point. I did remove it from Evap canister but I let it hang and vent to air. I'll double check that too. I'm thinking of going with self tapping screw into the trunk for a ground

 

[92awddsm]

That's a good point. I did remove it from Evap canister but I let it hang and vent to air. I'll double check that too. I'm thinking of going with self tapping screw into the trunk for a ground

Sand it down to bare metal when you attach it. And I would try a tapped bolt hole instead. Self tapping screws are too likely to come loose.

 

[boost97gst]

I personally used a dremel on every contact spot where i grounded when i did my rewire and battery relocation. It makes a HUGE difference. Grab a meter and see for yourself.

 

[lil corb]

Good call on sanding down first. I'm wondering if I should drive it more and see if my closed loop tune ltft lo changes. If no re tune needed then fuel pump was the problem and just needed a re tune after fixing the issue.
I'm still going to re do ground.

Thanks everyone, will keep everyone posted and hopefully I can finally run at the track. What grit sand paper works best?

 

[92awddsm]

80 grit works fine

 

[lil corb]

Another update. So I get my multimeter out and do some testing on my existing ground set up. What I found is it is a good grounding point. I'm getting consistent 13.20 ish with that ground and using the power wire from battery. That's after constant revs, turning lights on and off, coolant fans turning on so the pump and can see different voltage pull. Unless I'm checking it wrong but it looks like the ground isn't the problem. I'm thinking it was a bad fuel pump and now that I replaced it just needs a fresh closed loop tune.

 

[Car Cannibal]

These threads are sad to read, you get two members that have been down this path with experience and give accurate info on what the REAL problem is, then someone chimes in with a half truth,

The liquid doesn't affect what the needle says. The liquid is only there to dampen vibration on the needle.

And someone else give it a which I guess means stories over.
Really, so then why is the OP still experiencing pressure drop after driving it with a hot engine bay vs a cold one? Are you going to chime in with a Paypal payment to the OP since you were so sure about your diagnosis?

OP, you didn't need a new fuel pump in this case, you needed to spend that money on a cockpit electric fuel pressure gauge. Your new pump is probably a little stronger than the old one so you're seeing some variance in your trims, but it wasn't needed.

 

[92awddsm]

These threads are sad to read, you get two members that have been down this path with experience and give accurate info on what the REAL problem is, then someone chimes in with a half truth,
And someone else give it a which I guess means stories over.
Really, so then why is the OP still experiencing pressure drop after driving it with a hot engine bay vs a cold one? Are you going to chime in with a Paypal payment to the OP since you were so sure about your diagnosis?

OP, you didn't need a new fuel pump in this case, you needed to spend that money on a cockpit electric fuel pressure gauge. Your new pump is probably a little stronger than the old one so you're seeing some variance in your trims, but it wasn't needed.

I'm not going to argue with you. But before you start saying someone is wrong, you should do some research on why some gauges are liquid filled in the first place. That being said, dry gaugesare more prone to fluctuations due to teptemperature than liquid filled gauges. And most of the time, the gauge will read higher than actual pressure with heat.

 

[Afizzle]

I had this issue and it ended up being 1 of 2 things inside my AFPR. Where the ball on the diaphragm seats needs to be perfectly round. I had a small kink in my fuel line and it was causing air bubbles in the fuel system. This caused the ball to eat up the seat and leave me with inconsistent fuel pressure and a shaky needle.

I fixed it by ordering a new diaphragm because I was also getting a little fuel in my vac lines. Grabbed a tiny file and smoothed the seat out, then used my old perfectly round diaphragm and a hammer to reprint the ball shape back into the seat. Blew all the shavings out, installed new diaphragm and she holds rock solid again

 

[lil corb]

Appreciate everyone's help. I think I can mark this thread as resolved now unless another update is needed. I am 100% my afpr is in good working order. No kinks, or fuel leaks and holds pressure while car is off. I do think a new pump was in need and plus the fact that I was told by previous owner it was 190lph means I was going to pull it anyway.


Thanks everyone