Not off the top of my head, if I remember to, I’ll get that for you when I get home tonight.
Absolutely.
Fuel pressure question. Insufficient flow?
- Thread starter TheRadBaron
- Start date
TheRadBaron
Registered User
I’ve been delving pretty deep into pressure/flow charts on Walbro’s website and I’m learning a few things.
I’m specifically looking at their GSL line of inline pumps because those seem to be a good design for our purposes. One of the things that I don’t like about the PSD factory pump is that it comes with the factory style fuel line connectors and Id like to use AN fittings on the fuel pump.
But back to pressure/flow. I don’t know how much flow is too much for the factory return system to handle but I know the Holley Red pump is a common choice for mild IDIs and it’s rated at 97gph at low pressure. I figure that’s a good number to shoot for. I don’t want to use the Holley because it has reports of spotty longevity and I think the rotor-type pump is an inferior design compared to the inline, turbine-style pumps.
That Racetronix low pressure pump mentioned a few posts back is a GSL395 and it’s rated at around 45gph. From what I’m reading that’s marginal for our engines.
According to Walbro’s charts the pumps that are designed for higher pressure applications will flow more than the rated amount if used in lower pressure applications.
For example, the GSL392 is rated at around 67gph but that’s at around 50psi. At 5psi it looks like it flows more like 90-95gph.
I’m thinking this pump, used with a return style regulator, might be a good choice for a mildly modified IDI-T.
Any thoughts?
I’m specifically looking at their GSL line of inline pumps because those seem to be a good design for our purposes. One of the things that I don’t like about the PSD factory pump is that it comes with the factory style fuel line connectors and Id like to use AN fittings on the fuel pump.
But back to pressure/flow. I don’t know how much flow is too much for the factory return system to handle but I know the Holley Red pump is a common choice for mild IDIs and it’s rated at 97gph at low pressure. I figure that’s a good number to shoot for. I don’t want to use the Holley because it has reports of spotty longevity and I think the rotor-type pump is an inferior design compared to the inline, turbine-style pumps.
That Racetronix low pressure pump mentioned a few posts back is a GSL395 and it’s rated at around 45gph. From what I’m reading that’s marginal for our engines.
According to Walbro’s charts the pumps that are designed for higher pressure applications will flow more than the rated amount if used in lower pressure applications.
For example, the GSL392 is rated at around 67gph but that’s at around 50psi. At 5psi it looks like it flows more like 90-95gph.
I’m thinking this pump, used with a return style regulator, might be a good choice for a mildly modified IDI-T.
Any thoughts?
Larry P
Registered User
Drive the truck at WOT up a long hill on the interstate for a few minutes. Then pull over on the shoulder and bleed the Schrader valve. I would think that if the lift pump isnt keeping up, you'd see some air.
IDIBRONCO
IDIBRONCO
Yes it would work like you described. As long as you use a returning regulator, it doesn't matter how much pressure and flow the pump has. It will only send what your engine needs.
Be aware the Holley red and other pumps of that design have their own regulator built in. So when the pressure gets over what they are rated for they recirculate the fuel inside the pump itself.
So buy the pump with the built in regulator, or buy a high pressure pump that requires the external regulator. Whatever floats your boat.
IDIBRONCO
IDIBRONCO
Those don't use returning regulators. As far as the Holleys go, the only one that needs a returning regulator is the black. My Holley blue came with a regulator, but it's separate, not built in.
I'm also not sure how a pump with a built in regulator can give it's regulator too much pressure.
Stranger things?
I don't know that the red is internally regulated, but it seems like it is "rated @ x -free flow gpm...
More than needed but ....
My red is a 2019 model doesn't get exercised much.
IDIBRONCO
IDIBRONCO
I think that they're all rated at free flow, but I could be wrong on that.
I believe you are right...
TheRadBaron
Registered User
Well I decided to go with the factory Bosch #69909 electric fuel pump from the ‘99-‘04 PSD. This pump is the only one I could find that seemed to fit the bill and has pretty much universally good reviews. It’s specifically designed as a diesel lift pump and that seems like a big plus. The Walbro pumps I was looking at have mixed reviews on their reliability when you go digging.
So between that and the feedback in this thread suggesting that the PSD pump is a good choice swayed me to it.
I’m working out of town during the week so I’m not having as much time to work on my truck as I’d like but hopefully I’ll have it up and running later this winter.
At that point I’ll probably make another thread about the design of my fuel system.
I appreciate all the insight from the contributors here.
So between that and the feedback in this thread suggesting that the PSD pump is a good choice swayed me to it.
I’m working out of town during the week so I’m not having as much time to work on my truck as I’d like but hopefully I’ll have it up and running later this winter.
At that point I’ll probably make another thread about the design of my fuel system.
I appreciate all the insight from the contributors here.
So you are going to run a return style regulator? And that will be plumbed into the original return system?
TheRadBaron
Registered User
Yeah, I’ll be using a returning regulator. I’m replumbing every inch of fuel line in the truck. The return from the regulator will be separate from the return from the IP and injectors. I’ll be running everything in 3/8 line and I’m plumbing the IP/injector return in such a way that it should be capable of more flow than factory.
I’m keeping the dual tanks but I’m setting it up so that the front tank is the main tank, while the rear tank (38 gallon) will simply pump into the front tank to replenish it. There will be a separate fuel pump manually controlled with a switch for this. I’m ditching the tank selector valve but keeping the switch in the dash so that I can toggle back and forth between the two tanks’ fuel level sending units so that I can monitor the fuel level in both tanks.
I’m thinking that the second fuel pump will also be a Bosch 69909 so that there will be some built in redundancy in the system. If the main pump fails I’ll be able to just swap some lines under the truck and use the secondary pump to supply the engine.
I’m keeping the dual tanks but I’m setting it up so that the front tank is the main tank, while the rear tank (38 gallon) will simply pump into the front tank to replenish it. There will be a separate fuel pump manually controlled with a switch for this. I’m ditching the tank selector valve but keeping the switch in the dash so that I can toggle back and forth between the two tanks’ fuel level sending units so that I can monitor the fuel level in both tanks.
I’m thinking that the second fuel pump will also be a Bosch 69909 so that there will be some built in redundancy in the system. If the main pump fails I’ll be able to just swap some lines under the truck and use the secondary pump to supply the engine.
Similar threads
