Stock intank fuel pump feeding 255 inline?

[supravw]

I have a 92 Colt with a 4g63 going in it for the second time. First motor had a valve let go, the only reason I can think for it breaking is lean conditions, which leads to my question. Will having my stock pump feed a 255 inline pump work or will the stock pump just be a restriction? That is the setup I'm running right now. The only reason I didn't do an in-tank 255 is because I live in VT and rust and those little nuts that hold the pump cover on don't get along and I would most likely break every single one off. So will the setup I have now work or should I find another way? Thanks!

 

[throwedgsx]

Your stock fuel pump isn't going to pump enough fuel to feed the 255lph.

 

[ziggys95tsi]

Your stock fuel pump isn't going to pump enough fuel to feed the 255lph.

exactly

 

[throwedgsx]

If you do a twin pump setup up you want both pumps to flow at the same rate. If your secondary pump is smaller it's going to back the fuel up. Think of it like a dam in a river. If you go with higher flowing secondary pump, well, then your just wasting your money. The main pump is not going to be able to feed the second pump. I'd just go with the 255 intake pump and fabricate something so you don't have to worry about the rust.

 

[vaboys2ndgen]

I got a 255HP inline fuel pump FS, but yeah everyone pretty covered it.

 

[throwedgsx]

What size intake pump do you run?

 

[90laserRSfwd]

What size intake pump do you run?

stock I gather from his posted question.

To the OP: If you having issue's with rust on the bolts. Take the tank out of the car and let it sit in a very warm dry place (like a basement, near a furnace, this of course has it's risks). Or spray the bolts down 3 to 4 times a day with PB Blaster for about a week and use a vise scrips to remove the bolts, not a socket or screw driver.

 

[vaboys2ndgen]

What size intake pump do you run?

yeah changed my post, my bad. Was kinda misleading . I just picked up a dual walbro 255 intake setup, but currently only running a single 255HP pump on my 1g.

 

[Boosted98gsx]

255 in tank with a bosch 044 inline works very well.

 

[dsm-onster]

/\/\/\/\ and they don't flow the same either.

An inline pump will insure that your system will flow atleast what your intank pump will flow at it's lowest pressure. . . This is the same reson why we're able to push a turbo like the evo3 16g off the map in flow. The engine is an airpump just as much as the the turbo. . .

 

[supravw]

Thanks for all the replies, I will get the intank pump swapped out. I can either remove the stock fuel pump and place a line in it's place or get a dsm 255 and figure out how to mount it in the colt fuel pump assembly. Either way it looks like I'll be dealing with the rusted crap...

 

[gsxtasy]

Actually, a stock in tank pump is not a restriction if you're using it in conjunction with an inline pump. With an inline pump your in tank pump is flowing at no pressure, and even a stock pump at no pressure will flow quite a bit. Enough to feed a 255 inline.

The feeder pump(in tank) is just there to make sure there is enough fuel at the mouth of the inline pump. I think it's fine.

 

[We're on Boost]

Actually, a stock in tank pump is not a restriction if you're using it in conjunction with an inline pump. With an inline pump your in tank pump is flowing at no pressure, and even a stock pump at no pressure will flow quite a bit. Enough to feed a 255 inline.

The feeder pump(in tank) is just there to make sure there is enough fuel at the mouth of the inline pump. I think it's fine.

This sounds about right to me but I've never actually tried it. Wonder if anybody has ever measured the flow rate of the stock pump at 0 pressure? If it is a positive displacement type pump it could still be a flow restrictor to the inline pump at high flow rates.

 

[gsxtasy]

I would also like to see scientific proof of this, I'm curious as well.

 

[Boosted98gsx]

Thanks for all the replies, I will get the intank pump swapped out. I can either remove the stock fuel pump and place a line in it's place or get a dsm 255 and figure out how to mount it in the colt fuel pump assembly. Either way it looks like I'll be dealing with the rusted crap...

You can actually fit a bosch 044 in the tank of a 1g. Drill out the bulkhead, put an an bulkhead fitting in there, and strap the bosch to the support with a worm screw clamp. Just make sure to get the filter sock as well as a prepump filter.

 

[jrohner]

I don't see how to pumps in the same line can ever help much with flow.

If you use an impact, you may be able to get them off without breaking them off.

When I replaced the pump in my talon, it was very rusty looking but only 1 broke off. Just go for it and see what happens. If they break off, you should be able to get them out and put in some new bolts.

 

[Boosted98gsx]

I don't see how to pumps in the same line can ever help much with flow.

Series pumps don't increase overall maximum flow, what they do is maximize the pressure capabilities of using instead 1 pump. So if you start losing pressure at the top of your RPM band, adding another pump will help boost the first pumps abilities of getting the fuel to the rail.

Basically, you cannot get more fuel through the lines than the cross sectional area of the line will permit, but you can increase the fuel's velocity through that line helping to fill the ever increasing pressure drop at the rail as the engine's RPM's increase.

 

[dsm-onster]

And to add to the above, look at the walbro inline pump in series with (in line being fed by) the walbro 255 intank. Such a setup flow on average 25% more than just the inline pump (an intake pump with no pressure bleed). Such a setu only loses less than 6% flow if you up the boost from 20psi to 40psiflow at 40 psi is 41% more that a single walbro intank. A walbro intank pump can flo enoughto max out 850cc injectors (100%IDC) at 40psi boost & 43psi base fuel pressure. A series pump two walbro 255s can flow enough at 40psi boost & 43psi base to max out 1150cc injectors.

So an inline pump which flows as much as a stock intank pump coupled in series with a stock intank pump will likely increase fuel flow by up to 20% at 20-22 psi. At about 20 psi and 43psi base fuel pressure, the oem pump can flow about 100LPH; or enough fuel to max out 450cc injectors. 20% more flow would be 120LPH; or enough fuel flow to max otu 500cc injectors. A pump with more flow than that in the line will just let the stock pump "freewheel" and you'll get the flow of the stronger pump. Like running a tiny supercharger on a V8. Boost will go down but you won't lose flow, you're motor won't be neccesarily weaker without the supercharger.