Fuel system upgrade
by jim@foreignaffairs » Tue Feb 07, 2006 10:51 am
Keep in mind that if you are planning to do this next fuel system upgrade, you will need to have some understanding of how the fuel system works, you will have to be able to figure some things out for yourself, you will have to have all the necessary tools and know-how to pull it off.
The hoses are of the same type you already recieved from me, not hard lines like stock. This makes them flexable and easy to route.
The original fuel pump has to be removed from the tank in order to build the system I have. The only part of the car I had to modify for my system that would have to be replaced should I want to go back to stock is the top round plastic molding for the fuel tank. The round piece has a hole drilled in it to mount a 90 degree bulkhead fitting (-6 size). A fuel pick-up tube is attached inside that reaches to the bottom of the tank and sucks up the fuel. On the other side of the 90 degree bulkhead fitting is another hose attachment that leads down to the fuel pump. The hoses are custom cut to length as you go so you have to put them together as you go, but the new reusable type just press together so you can build custom hoses yourself.
The inlet on the fuel pump is huge on the type I used, 5/8" I believe, so you will need a reducer to go from the 3/8" hose coming from the tank to adapt it. The longest piece of hose is the one that goes from the fuel pump outlet to the filter inlet, but as a recall it was only 6-7 feet long and runs along the frame rail next to the stock lines. I used about a foot of -10 line and less than 12 feet of -6 line all together.
I did consider a system like trd4Life, which is just as effective but does require taping return hose fittings on the fuel rail ends to go to the pressure regulator. Fuel temps usually are higher with that type system since the fuel rails get warm and continuosly heat the fuel, over and over. So I would suggest a fuel cooler if you go that way.
It sounds like DatSRBoi has it straight. I don't know what the rating on the Walbro pumps is. Fuel pumps are rated 2 ways, by pressure and amount of flow. A sewer pipe flows a lot under very low pressure. A squirt gun flows very little under high pressure. Both pressure and volume matter. You want to maintain high pressure with enough volume to always feed the motor even at max load. If the pressure goes down during high loads, the fuel system will be harder to tune because the injectors will see changing pressure. The best way to test this is with a fuel pressure gauge. The Bosch pump I use flows a huge amount as fuel pumps go that's why the inlet is 5/8 inch. And it maintains that flow at high pressure. But I admit it is overkill. A smaller pump would be adequite as long as pressure doesn't drop at high demand. A lot of small pumps will have a good max pressure rating until they are asked to provide lots of fuel, then the pressure drops too low because they can't maintain that pressure at high flow rates. A an example. the stock pump can't maintain pressure at the flow levels we need even though it may have enough pressure at lower flow.
The hoses are of the same type you already recieved from me, not hard lines like stock. This makes them flexable and easy to route.
The original fuel pump has to be removed from the tank in order to build the system I have. The only part of the car I had to modify for my system that would have to be replaced should I want to go back to stock is the top round plastic molding for the fuel tank. The round piece has a hole drilled in it to mount a 90 degree bulkhead fitting (-6 size). A fuel pick-up tube is attached inside that reaches to the bottom of the tank and sucks up the fuel. On the other side of the 90 degree bulkhead fitting is another hose attachment that leads down to the fuel pump. The hoses are custom cut to length as you go so you have to put them together as you go, but the new reusable type just press together so you can build custom hoses yourself.
The inlet on the fuel pump is huge on the type I used, 5/8" I believe, so you will need a reducer to go from the 3/8" hose coming from the tank to adapt it. The longest piece of hose is the one that goes from the fuel pump outlet to the filter inlet, but as a recall it was only 6-7 feet long and runs along the frame rail next to the stock lines. I used about a foot of -10 line and less than 12 feet of -6 line all together.
I did consider a system like trd4Life, which is just as effective but does require taping return hose fittings on the fuel rail ends to go to the pressure regulator. Fuel temps usually are higher with that type system since the fuel rails get warm and continuosly heat the fuel, over and over. So I would suggest a fuel cooler if you go that way.
It sounds like DatSRBoi has it straight. I don't know what the rating on the Walbro pumps is. Fuel pumps are rated 2 ways, by pressure and amount of flow. A sewer pipe flows a lot under very low pressure. A squirt gun flows very little under high pressure. Both pressure and volume matter. You want to maintain high pressure with enough volume to always feed the motor even at max load. If the pressure goes down during high loads, the fuel system will be harder to tune because the injectors will see changing pressure. The best way to test this is with a fuel pressure gauge. The Bosch pump I use flows a huge amount as fuel pumps go that's why the inlet is 5/8 inch. And it maintains that flow at high pressure. But I admit it is overkill. A smaller pump would be adequite as long as pressure doesn't drop at high demand. A lot of small pumps will have a good max pressure rating until they are asked to provide lots of fuel, then the pressure drops too low because they can't maintain that pressure at high flow rates. A an example. the stock pump can't maintain pressure at the flow levels we need even though it may have enough pressure at lower flow.
- jim@foreignaffairs
- Regular SolaraGuy Member
- Posts: 67
- Joined: Sat Aug 23, 2003 8:49 am
- Location: Portland, Oregon
ITs not that I dont wanna take the time and learn everything, but I gets a little scared around workign with fuel lines and such.
I haven't had the time to do more searching, but I'm still looking at how much pressure the 190 Walbro pump provides. Anybody else have any luck finding that?
