jclayc

iTrader: (8)

Hi everyone,

Long post for 2 tiny issues...

I recently replaced my stock fuel pump with a Walboro 255. At the same time, I installed Holley rails and a Fuellab fuel pressure regulator (PN 52501-1). This also meant running a -6 AN return line, which I plugged in to the stock return port on top of the tank using Russell PN 640863 (-6 AN Male to 5/16" SAE Quick-Disconnect Female Push-On EFI Fitting). Inside the tank, I did run the return line down to where the stock regulator used to be using a barbed fitting and submersible hose. Finally, instead of blocking off the stock fuel filter's return port, I replaced the stock filter with FRAM PN G7315 - same dimensions. I'm running 58psi and am getting no leaks.



Here are my two small issues:
When running at Pocano North course - which includes 1/3 of the banked speedway at ~130mph - after starting with a full tank, after around 15 minutes in the session with like 3/4 tank left, I started sucking air instead of gas when going around the speedway. It used to take being down to 1/2 a tank before turning right at prolonged high speeds would force me to suck air. The cause would naturally be that my fuel pickup inside the tank is not in the gas any longer. It also follows that, when installing the new pump, the pickup got moved so it sucks air sooner than before. The cure would be to make sure the pickup is deeper in the tank. Can you give me some feedback - looking at the pic below, am I correct that the white plastic tube is the main pickup, also fed by the black hard hose coming over from the left hand saddle tank? If so, can you confirm that this is the tube that is higher than before and sucking air - what I need to make sure is lower in the tank? Finally, I don't think that white tube ever had anything on the end of it (like a hose) but to make sure the pickup goes deeper in the tank, would it be advisable to attach a few inches of submersible hose to it?



Second general question - as I said, I have zero leaks - nothing even damp at any junction - but I still smell gas when I keep the car in the garage. it seems to be coming from the area around the tank, not from under the hood. The gasket is in place between the fuel bucket and the tank and the lock ring is secured all the way. Any thoughts on a possible cause? It would either have to be my -6 to 5/16 adapter or the bucket and ring aren't sealing properly.

Interestingly (related to either issue or not, I don't know) when I took the lock ring off this AM to check everything over, like a gallon of gas came out of the bucket hole as soon as I unlocked the lock ring. The car was on a flat surface. I do have a full fuel tank but it surprised me that gas would actively come out of the hole when, a few days ago with a tiny bit more gas in the tank, gas did not pour out the hole when removing the lock ring.

Thanks for reading!

VeryWhiteDevil

iTrader: (9)

what did you do with the Evap line?

jclayc

iTrader: (8)

(EVAP lines are something I don't know a ton about, *L* so I've considered this may be an element)

My best answer is that nothing changed in EVAP since before the fuel system changes... in the engine bay, the EVAP line runs into the driver's side inlet in my FAST just behind the throttle body.

There is a black connector with green "insides" up near the fuel filter that I assume has something to do with EVAP but I don't know what it is and didn't mess with it (pic below from philistine's duel pump how to)

jclayc

iTrader: (8)

Looking at the assembly diagram, I wonder if one of the evap lines came loose (parts 10 to 8 to 6 to 36 to 35) or I wonder what the symptomology would be if the internal crossover fuel line #34 came off the sender side?

VeryWhiteDevil

iTrader: (9)

I would look there

jclayc

iTrader: (8)

ugh, means dropping the tank. Maybe i'll go ahead and do cradle bushings then too

bmylez

iTrader: (3)

That right there is a good idea.

Grenade19

nice diagram definitely do the cradle bushings at the same time

Junior-1

iTrader: (1)

Lost out on a podium finish thanks to the hard right (T9) at the Octopus on T-Bolt last month because of this.

Let me know what fix you come up with. I was leaning towards a Swirl Pot setup...

http://atlinc.com/atl-swirl-pot-st540.html

jclayc

iTrader: (8)

that swirl pot is a sweet looking setup. I assume it works better than a fuel cell with internal baffling and "gates"? if I hadn't just upgraded my pump & didn't need my spare tire well to fit a 4th slick, I might go ahead and go all in on a cell setup

So can anyone confirm for me that the white plastic tube pictured above is not supposed to have anything additional connected to it (other than the crossover line to the other side of the tank)?

Before I pull the tank, maybe I'll replace the EVAP canister purge valve and see where I go from there...

VeryWhiteDevil

iTrader: (9)

it has been so long since I've been in the tank, I cannot remember. was that white piece part of the OLD FPR in tank?

Junior-1

iTrader: (1)

My first thought was to just throw a cell in it. But the builder is telling me by the time you factor in the required bars and modifications it will get expensive in cost and in weight...

philistine

iTrader: (2)

The "white part" in the pic looks like the jet pump connection. Your primary pump (single intake pump) takes suction inside the fuel module. The fuel module is covered (flooded) with fuel and takes suction from within. The discharge flow from that pump goes through a Venturi section and creates a low pressure zone. Fuel from the other side of the fuel tank (driver's side) is then carried through the that "white part" through the low pressure zone - the jet pump or just call it suction.

The single discharge up to the outlet of the fuel module then consists of fuel pumped directly from the fuel module and mixed with the fuel from the driver's side - 2 inputs, 1 outlet.

The reason for that system is to use a single pump that can take suction from both halves of the fuel tank at the same time. The GM engineers decided to use the efficiency of incorporating a jet pump for the secondary suction on the driver's side.

As far as smelling fuel vapor, the AN connectors in theory provide a vapor seal but that is not always the case. With clean hands or cotton swab, check those connections and sniff it. Make sure those connectors are tight. If fuel is coming from those those connectors and you feel you have them tight then you can use Aviation Form-A-Gasket - Permatex #80017. That stuff is leakproof low modulus liquid sealant good for E85 or even race fuel and up to 400F.

Hope that helps!

jclayc

iTrader: (8)

yeah, that permatex #3 aircraft sealant is neat stuff - goopy but works well and is gasoline resistant. I'll give it a try on the AN threads.

what you've said about the pickups makes sense - that the main pickup is inside the fuel bucket itself (hence the filter in the bucket). so, when the pump is sucking air, it would simply be that the bottom of the bucket (which is truly at the top of the back of the passenger's side saddle) is in the air.

I'm really digging the swirl pot idea now that I read more about it. if you use it with a stock tank, where would you put it? I'd hate to just stick it back in the trunk because, with no back seat, it's technically part of the passenger compartment.

Junior-1

iTrader: (1)

That's what I have been working on. First thought would be in my spare well since I am fully gutted. I have a closeout panel between the trunk and back seat anyways.
The Bill Black guys ran a cell right in the trunk area and the Powell cars had the cell right in the old tank position.
I'm convinced there has to be a better way than just starting every race with a full topped off tank adding yet another 50-60 pounds into the mix...

Sssnake

I had an issue with vapor leakage (smell) on a fuel pressure sensor under the hood. The pipe thread on the sensor was leaking slightly. The stuff Jaysen/Phili mentioned, Aviation Form-A-Gasket - Permatex #80017, took care of it.

jclayc

iTrader: (8)

Sssnake - the only fuel pressure sensor I know of is on top of the tank. where is the sensor under the hood?

well, I tried a combination of replacing the EVAP solenoid, sniffing around and using the aviation sealant but haven't gotten the smell to go away. No codes, BTW. I may try just replacing the gas cap since that's cheap/easy.

It's definitely coming from the fuel tank area and not under the hood. the best I can tell, it's not coming from around the fuel pump "hole". It's not coming from the fuel filter, I've smelled and watched it while the car is running and it's dry as a bone. That just leaves all the EVAP crud on top of the tank. see if this makes sense:

The last time I filled up, it was with a gas can at the track and i filled it until it spilled out (first time ever doing that, I believe). Also keep in mind I recently opened the fuel pump hole and like a gallon of gas came pouring up/out of the hole. I'm thinking I "overfilled" the tank and soaked the EVAP filter.

Sssnake

Mine has an aftermarket fuel pressure sensor mounted at the rail. I only mentioned it to reinforce the selection of the aviation form a gasket product.

I am having issues with my evap system. Shop did my fuel pump install (the only thing left on this car I didn't do myself) and I suspect they buggered it up. When I fill the tank fully the car surges wildly on restart and eventually dies. I ended up capping the evap feed and tuning out the evap adjustment. When I put in the CS 8.8" rear I will investigate fully. Even with this evap issue I did NOT smell gas (after I fixed the fuel pressure sensor issue). Just sayin' all evap problems don't necessarily give you a smell issue.

jclayc

iTrader: (8)

thanks for the reply. yeah, logic tells me new things/connections are more likely to be the cause of gas smell (particularly because I'm not getting any MILs) but the connections under the hood don't smell and that just leaves the return line connection at the pump, the fuel pump "hole" itself and the factory connections around the fuel filter. None of those appear to leak or smell. I'm down to EVAP-related causes... I think.

I thought it might have been b/c my AN hose and AN fittings were from different manufacturers - I've had that cause tiny leaks in oil lines before - but I replaced the fittings to match the hose manufacturer and didn't seem to solve anything.

jclayc

iTrader: (8)

something odd I noticed yesterday - with the engine on, my fuel pressure is right at 60 psi, steady. When I turn on the ignition with the engine off, the pressure goes up to 60 but then slowly starts decreasing. After about 2 minutes, it was down to around 55 psi.

does anyone know if the EVAP system would vent pressure off in that scenario? I don't think so... I think EVAP is just for over-pressure systems.

If the EVAP isn't the reason for losing pressure with the pump on but engine off, that points to a leak, in my opinion. I can start cutting elements out of the system and doing a pressure test to narrow whether it's an injector leak, FPR leak, etc.