Dropping Fuel PSI
05-28-2017, 11:03 AM
#1
Running Guns & Moonshine
Thread Starter
Dropping Fuel PSI
My current thought is a bad pump, since I had bad luck with its predecessor.
The car is supercharged and I am running the Casper hot wire kit, kb bap, and a racetronix walbro 255lph in tank pump. Filter/fpr was replaced when I bought the car 4 years ago.
The first racetronix pump came to me dead in the box. Took me a bit to determine that because I presumed new = working in that case (mostly because I didn't want to bust into the tank again) but that's why it was. I ordered a second same pump, dropped it in, and it instantly ran fine.
Until now.
I've been limping the car on factory tune and injectors until I could get a proper tune for the blower. Went down to see Doug @ECS for that yesterday and we hit a few snags with the fuel system.
First, the 20a fuse for the Casper kit went. Then the 20a fuse for the bap kit. Replaced both with 30a and no issue. Ran the engine up again, but the pump is now dropping psi at 4500rpm.
It looks like a weak pump.
I'll borrow a volt meter and look around. Cross wire the Hobbs kit to test bap, try factory harness on pump.
But any other thoughts on this? Weak ground?
Also, I've only ever used walbro before. I'd the lpe pump just twice the price for a fancy name? What other brands are trusted? Racetronix is off my list.
The car is supercharged and I am running the Casper hot wire kit, kb bap, and a racetronix walbro 255lph in tank pump. Filter/fpr was replaced when I bought the car 4 years ago.
The first racetronix pump came to me dead in the box. Took me a bit to determine that because I presumed new = working in that case (mostly because I didn't want to bust into the tank again) but that's why it was. I ordered a second same pump, dropped it in, and it instantly ran fine.
Until now.
I've been limping the car on factory tune and injectors until I could get a proper tune for the blower. Went down to see Doug @ECS for that yesterday and we hit a few snags with the fuel system.
First, the 20a fuse for the Casper kit went. Then the 20a fuse for the bap kit. Replaced both with 30a and no issue. Ran the engine up again, but the pump is now dropping psi at 4500rpm.
It looks like a weak pump.
I'll borrow a volt meter and look around. Cross wire the Hobbs kit to test bap, try factory harness on pump.
But any other thoughts on this? Weak ground?
Also, I've only ever used walbro before. I'd the lpe pump just twice the price for a fancy name? What other brands are trusted? Racetronix is off my list.
05-28-2017, 11:28 AM
#2
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I had the racetronix 255 pump/harness on my car for a few years and never had a problem with it... their pump is also a walbro as far as I know unless they have changed, in my experience they have pretty nice stuff... do you have the bap looped so you get full voltage to the pump or are you using that adjustment ****?... do you have a pressure gauge in the car?... try disconnecting the bap and test the pressure using just the pump then plug the bap back in and jump the hobbs switch and see what the pressure does... it could be a number of things, maybe as simple as one of the grounds for the hobbs but you will have to start testing things to narrow it down