Fuel tank, fuel pump, fuel pickup for tbi

[TexasJ10]

When using the standard j10 tank and external pump, how much of the tank capacity is usable after a tbi conversion? Some forums indicate 3/4 at best, others say no problems at all.

I have been running around the Internet exploring the baffled tank benefit, and the claim that most modern tanks are not baffled at all. It appears that the one big difference between the days when engines were carbureted, and today, has much more to do with the creation of a fuel module in the tank rather than baffling. The module, a plastic mini tank that surrounds the in tank pump, allows gas to be drawn in by the pump, but also receives all of the return line fuel, and has a Venturi pump that sucks gas from outside the module, into the module. The Venturi pump is driven by excess fuel pump pressure and volume. Somehow the main pump knows to draw all the fuel it can from the tank first, but if the pickup is uncovered, it draws from the module.

If the full tank capacity on a j10 tbi conversion is available for use, then I will just install the external pump and be done with it. If the full capacity is not available, I might mess around creating some sort of internal or external fuel module. I have no interest in dual electric pumps and surge tanks. Perhaps a 2" diameter tube 12 inches long with the bottom closed off other than a one way valve that allows fuel to be drawn in by the pickup. I think it could be attached to the pickup tube to hold it in place. The return fuel would be directed into the 2" tube, and a Venturi pump added to draw additional fuel in at all times. The Venturi pump would require a feed from the fuel pump, but a lot of the walbro pumps already come with the Venturi feed so they will work in the stock modules.

Has anyone tried something like this? The opening into our tanks is painfully small so I'm not sure how much capacity an in tank module would have. I'm just thinking out loud here and any all thoughts are welcome.

[Mr. Goatman]

Well, I'm interested to see the answers on this. I am no expert on the subject but am in the process on installing a TBI conversion myself. It would seem that the same amount of gas is available from the tank regardless of the fuel delivery system if the "in tank" components are the same. Mine uses an external electric pump and all the pickup stuff in the tank is OEM stock. Other than the increase in circulation via the return line I can't see why using a TBI vs a carb would use less of the gas in your tank.

[babywag]

Not sure why you would have less useable fuel just by running an external pump?

I just stuffed a GM TBI fuel pump in my tank and called it done.
Cheaper than an external, off the shelf parts available just about anywhere.
External pumps were too expensive for my cheap self.

[TexasJ10]

Well, I'm interested to see the answers on this. I am no expert on the subject but am in the process on installing a TBI conversion myself. It would seem that the same amount of gas is available from the tank regardless of the fuel delivery system if the "in tank" components are the same. Mine uses an external electric pump and all the pickup stuff in the tank is OEM stock. Other than the increase in circulation via the return line I can't see why using a TBI vs a carb would use less of the gas in your tank.

As I understand it, the amount of fuel in the tank is obviously the same, but the tbi doesn't like a momentary lapse in the constant flow of fuel like might occur in a turn with a less than full tank of gas. A carburetor doesn't care because it has a reserve in the fuel bowl and the fuel is under much lower pressure requirements. The tbi needs constant flow and pressure. Some folks have reported that they can't let their tank get below a certain level or the engine stalls at certain times

[Mr. Goatman]

Tony, Does that sending unit work with the late wagoneer gauge?

[TexasJ10]

Not sure why you would have less useable fuel just by running an external pump?

I just stuffed a GM TBI fuel pump in my tank and called it done.
Cheaper than an external, off the shelf parts available just about anywhere.
External pumps were too expensive for my cheap self.

The way you set it up is something that I have been considering as we'll. It looks like you just cut off the fuel feed line at a level that puts the fuel pump intake at the bottom of the tank, right. I like the simplicity of that. Any issues with using all the fuel in the tank? I think I have one of those internal pumps around here somewhere. It seems like it was a walbro that put out about 50 psi and around 22 lph and came out of a fuel module for a suburban.

[babywag]

I've never had any issues on either of mine w/ fuel delivery.
I can run them dry intentionally or by accident.
Regularly see ~19 gallons on pump screen when filling them.

Mr. Goatman
The sender I'm using reads backwards on late model wags.
E=Full and F=Empty
I just keep track of mileage.

I have the internal pump on my '88, and an external pump on my '90.
Either method works, just a matter of time.
The external pump was about 3x the cost of the internal.

[jeepfan93]

BabyWag, would you happen to have a thread on your conversions? Gearing up for this myself. Pretty sure I've got the logistics covered, but the tuning part and BIN files has me concerned. I'll be going 'burban tank myself so intank pump for me here. TIA

[babywag]

BabyWag, would you happen to have a thread on your conversions? Gearing up for this myself. Pretty sure I've got the logistics covered, but the tuning part and BIN files has me concerned. I'll be going 'burban tank myself so intank pump for me here. TIA

No, I don't really...just 'bits and pieces.
Just start your own new thread and post up any questions you have.

Everyone has to start somewhere, you'll learn as you go, and plenty of help if needed.

[Wagn Man]

Got a part number on that pump, or at least common vehicle info on it? Not sure why I have never thought of that.

Not sure why you would have less useable fuel just by running an external pump?

I just stuffed a GM TBI fuel pump in my tank and called it done.
Cheaper than an external, off the shelf parts available just about anywhwhere.
External pumps were too expensive for my cheap self.

[babywag]

Airtex PN#E3902
Strainer Airtex PN#FS1

~$35 for both depending on where you buy 'em.

Used in dozens of GM car/truck models take your pick LOL.

BUICKCENTURY(1985 - 1988)BUICKSKYHAWK(1985 - 1987)BUICKSKYLARK(1986 - 1987)BUICKSOMERSET(1986 - 1987)BUICKSOMERSET REGAL1985CADILLACBROUGHAM(1990 - 1992)CADILLACCIMARRON(1985 - 1986)CADILLACDEVILLE(1985 - 1986)CADILLACFLEETWOOD(1985 - 1986)CHEVROLETASTRO(1985 - 1994)CHEVROLETBLAZER(1987 - 1994)CHEVROLETC1500 PICKUP(1988 - 1995)CHEVROLETC1500 SUBURBAN(1992 - 1995)CHEVROLETC2500 PICKUP(1988 - 1995)CHEVROLETC2500 SUBURBAN(1992 - 1995)CHEVROLETC3500 PICKUP(1988 - 1995)CHEVROLETCAMARO(1985 - 1992)CHEVROLETCAPRICE(1985 - 1990)CHEVROLETCAVALIER(1985 - 1986)CHEVROLETCELEBRITY(1986 - 1988)CHEVROLETEL CAMINO(1985 - 1987)CHEVROLETG10(1987 - 1995)CHEVROLETG20(1987 - 1995)CHEVROLETG30(1987 - 1995)CHEVROLETIMPALA1985CHEVROLETK1500 PICKUP(1988 - 1995)CHEVROLETK1500 SUBURBAN(1992 - 1995)CHEVROLETK2500 PICKUP(1988 - 1995)CHEVROLETK2500 SUBURBAN(1992 - 1995)CHEVROLETK3500 PICKUP(1988 - 1995)CHEVROLETLLV(1987 - 1993)CHEVROLETLUMINA APV(1990 - 1995)CHEVROLETMONTE CARLO(1985 - 1988)CHEVROLETR10 PICKUP1987CHEVROLETR10 SUBURBAN(1987 - 1988)CHEVROLETR1500 SUBURBAN(1989 - 1991)CHEVROLETR20 PICKUP(1987 - 1988)CHEVROLETR20 SUBURBAN(1987 - 1988)CHEVROLETR2500 PICKUP1989CHEVROLETR2500 SUBURBAN(1989 - 1991)CHEVROLETR30 PICKUP(1987 - 1988)CHEVROLETR3500 PICKUP(1989 - 1991)CHEVROLETS10 BLAZER(1985 - 1994)CHEVROLETS10 PICKUP(1985 - 1995)CHEVROLETV10 PICKUP1987CHEVROLETV10 SUBURBAN(1987 - 1988)CHEVROLETV1500 SUBURBAN(1989 - 1991)CHEVROLETV20 PICKUP1987CHEVROLETV20 SUBURBAN(1987 - 1988)CHEVROLETV2500 SUBURBAN(1989 - 1991)CHEVROLETV30 PICKUP(1987 - 1988)CHEVROLETV3500 PICKUP(1989 - 1991)GMCC1500 PICKUP(1988 - 1995)GMCC1500 SUBURBAN(1992 - 1995)GMCC2500 PICKUP(1988 - 1995)GMCC2500 SUBURBAN(1992 - 1995)GMCC3500(1988 - 1995)GMCCABALLERO(1985 - 1987)GMCG1500(1987 - 1995)GMCG2500(1987 - 1995)GMCG3500(1987 - 1995)GMCJIMMY(1987 - 1994)GMCK1500 PICKUP(1988 - 1995)GMCK1500 SUBURBAN(1992 - 1995)GMCK2500 PICKUP(1988 - 1995)GMCK2500 SUBURBAN(1992 - 1995)GMCK3500(1988 - 1995)GMCR1500 PICKUP1987GMCR1500 SUBURBAN(1987 - 1991)GMCR2500 PICKUP(1987 - 1989)GMCR2500 SUBURBAN(1987 - 1991)GMCR3500 PICKUP(1987 - 1991)GMCS15 JIMMY(1985 - 1991)GMCS15 PICKUP(1985 - 1990)GMCSAFARI(1985 - 1994)GMCSONOMA(1991 - 1995)GMCV1500 PICKUP1987GMCV1500 SUBURBAN(1987 - 1991)GMCV2500 PICKUP1987GMCV2500 SUBURBAN(1987 - 1991)GMCV3500 PICKUP(1987 - 1991)GMCYUKON(1992 - 1994)OLDSMOBILEBRAVADA(1991 - 1992)OLDSMOBILECALAIS(1985 - 1987)OLDSMOBILECUTLASS CIERA(1985 - 1988)OLDSMOBILECUTLASS CRUISER(1987 - 1988)OLDSMOBILEFIRENZA(1985 - 1987)OLDSMOBILESILHOUETTE(1990 - 1994)PONTIAC6000(1986 - 1988)PONTIACBONNEVILLE1986PONTIACFIERO(1985 - 1988)PONTIACFIREBIRD(1985 - 1992)PONTIACGRAND AM(1985 - 1987)PONTIACGRAND PRIX(1986 - 1987)PONTIACJ20001985PONTIACPARISIENNE(1985 - 1986)PONTIACSUNBIRD(1986 - 1987)PONTIACTRANS SPORT(1990 - 1995)

[TexasJ10]

Do you put a high pressure filter after the in tank pump? I guess that is how the gm stuff is set up?

[babywag]

Yes, I used a filter after pump before TBI.
Application is for an '84 corvette. 3/8" inlet/outlet.

I ran a new 3/8" steel hard line from the tank to the engine bay.
Used the existing 5/16" line for the return, and removed the 1/4" line.
Also on the sending unit I removed the 1/4" line and used 3/8" there as well, again reusing the 5/16" for the return.

On my '90 I used the existing 5/16" and 1/4" lines, haven't had any issues w/ fuel delivery.

[csuengr]

Not sure why you would have less useable fuel just by running an external pump?

I just stuffed a GM TBI fuel pump in my tank and called it done.
Cheaper than an external, off the shelf parts available just about anywhere.
External pumps were too expensive for my cheap self.

I did the same thing on my CJ when I put the LT1 in. I didn't use the plastic bag though. I can pretty much run my tank dry before there are any issues. The stock pumps have a check valve in them that retains pressure. The external pumps are also very loud.

[Bill USN-1]

Just a couple of notes based on some of the feed back.

1. Fuel pick up is determined by the pickup tube placement in the tank.
Yes fuel can slosh and at very low tank levels you can suck some air if you are driving a ralley cross. I have run stock tanks with external pumps since my first one 12yrs ago.
Have off roaded all over the world with it....no issue.
If you really feel you need a sump then a simple external surge tank works. A piece of exhaust pipe capped on the ends and weld some 14 pipe bungs on it. Feed in the top and draw out the bottom. Works like fuel bowl.

2. The style of pump makes no difference. Internal or external. It just needs to be able to maintain the pressure and the volume of fuel needed.
The stock GM TBI is marginal and most GM guys replace them with the TPI pump. The TBI pump works in stock applications but if you try to hop up your 360 or 401.....?

3. External pumps make no more noise than an internal.....
It's all in the pump design and the installation.
If you don't run 3/8 feed and 5/16 return line then you can get noise.

4. External pumps cost more...the ford E2000 can be had for $25 on ebay.