Modern in tank pump in older cars, anyone doing this?

68roadster · Post by **68roadster** » Sun Feb 11, 2007 5:16 am

I am considering how I would adapt a msefi system to a 68 Corvette. Anyone out there who put a modern fuel pump in an older tank?

THe reason I want to do this is some of the modern pumps have a plastic housing or canister containing the pump. It appears the return line goes into the canister to help prevent fuel starvation of the pump.

I posted about the specific pump I am considering in fuel delivery, but thought surely someone else has done this.

Ace McCool · Post by **Ace McCool** » Sun Feb 11, 2007 5:55 am

There are folks like Rock Valley who make custom tanks like you are asking about but they are pricey. Bottom line is its doable but requires some significant effort. Have you considered going the external surge tank route? I have had good success with this approach and its quite a bit easier to implement. You need a low pressure pump to fill the surge tank and the normal high pressure pump to pressurize the line from the surge tank. Both sides need a return to the tank. On the Corvette, you can mount this gear on the crossmember that supports the spare tire support.
jc

68roadster · Post by **68roadster** » Sun Feb 11, 2007 5:18 pm

I see that would work as a different route but possibly more complex than I would need (2 pumps and an extra vessel). Someone I have conversed with on Corvetteforum.com has used a similar set up with a 1991 ford bronco fuel pump and put quite a bit of work in to that setup fabricating the fuel tank sender. He tells me that this has been great on his 1968 Corvette with no fuel starvation issues as before when he used an external pump with no sump or surge.

I am suprised that noone posted they have done this and if it works for me I will share it with this forum. I'll be back with more questions on trying to find the right type pump, and othe parts for my planned TBI setup.

Cheers.

PSIG · Post by **PSIG** » Sun Feb 11, 2007 9:07 pm

68roadster,

This subject has been covered many times and a search for more info may prove useful. You already have your low pressure pump - the factory mechanical one. Many cars have been converted by simply routing the flow to a small surge tank and then the high pressure pump. This is a version of what JC was describing, works very well and is both simple and inexpensive.

Various surge tanks have been used including factory VW/BMW types, small fire extinguisher bodies and even modified remote spin-on style fuel filters like Fram markets that can do double-duty. If you want to get really tidy, place a standard in-tank EFI pump inside the surge tank. Very clean. The original pickup and tank in your roadster is unsuitable alone and results in intermittent starvation and disappointment unless the fuel tank is kept over 1/2 full.

The add-on surge tank and HP pump is a small package that's easily hidden and effective. I mounted the pair in the driver's fender forward of the wheelwell, which made the install a splice-in affair and the HP lines short to the rails and back. Only the return line from the surge tank to the main tank took any time to install - and that's not a biggie.

Remember the stock pump will be flowing at nearly zero pressure so the volume is large and will feed a lot of horsepower. Do as you will but the surge tank system is cheap, reliable and can be fabricated and installed in an afternoon without modifying your original tank and pickup/sender. It's worth considering based on the many experiences available on this forum.

David

d72hemi · Post by **d72hemi** » Mon Feb 12, 2007 1:02 am

PSIG wrote:68roadster,

This subject has been covered many times and a search for more info may prove useful. You already have your low pressure pump - the factory mechanical one. Many cars have been converted by simply routing the flow to a small surge tank and then the high pressure pump. This is a version of what JC was describing, works very well and is both simple and inexpensive.

Various surge tanks have been used including factory VW/BMW types, small fire extinguisher bodies and even modified remote spin-on style fuel filters like Fram markets that can do double-duty. If you want to get really tidy, place a standard in-tank EFI pump inside the surge tank. Very clean. The original pickup and tank in your roadster is unsuitable alone and results in intermittent starvation and disappointment unless the fuel tank is kept over 1/2 full.

The add-on surge tank and HP pump is a small package that's easily hidden and effective. I mounted the pair in the driver's fender forward of the wheelwell, which made the install a splice-in affair and the HP lines short to the rails and back. Only the return line from the surge tank to the main tank took any time to install - and that's not a biggie.

Remember the stock pump will be flowing at nearly zero pressure so the volume is large and will feed a lot of horsepower. Do as you will but the surge tank system is cheap, reliable and can be fabricated and installed in an afternoon without modifying your original tank and pickup/sender. It's worth considering based on the many experiences available on this forum.

David

Do you have any pictures of this type of setup? I think this may be best for my 72 Dodge Charger MS convertion, it sound easy.

Ian

68roadster · Post by **68roadster** » Mon Feb 12, 2007 5:26 am

PSIG
Those are great ideas. Thanks for the clarification. This is probably what Ace and someone else was trying to tell me. I find it difficult to search for information since this is all new to me (i.e. what words do I put in a search since I don't know which way to go). Only EFI I have been around was a mystery that I simply took back to the dealer. There were no other similar cars I saw in the list of success stories.

renns · Post by **renns** » Mon Feb 12, 2007 7:36 am

To convert my car from carb to efi, I removed the tank, and modified it to accept a later model drop-in pump assembly. For my vehicle this involved a number of steps:

1.) Scavenge efi tank parts from a donor car - pump assembly, slosh cup (spot-welded to inside bottom of tank), and mounting flange.
2.) Cut and modify my tank to accept mounting flange.
3.) Mount 'slosh cup' into inside of my tank to protect pickup from starvation under accel/decel/cornering.
4.) Cap existing feed, return, vent lines, and use those built into the newer pump assembly.
5.) Assemble and test.

In the end it worked out great. I had initially ran with the low pressure pump feeding a small header tank, then efi pump to the engine. The in-tank method is much cleaner, with less external fuel connections, one less pump, and potentially much quieter operation.

68roadster · Post by **68roadster** » Mon Feb 12, 2007 8:26 am

renns,
That was the idea given to me by another guy with a 68 Corvette. He did a bunch of fab work on the sending unit, but I think I found one that will drop in my tank.
Problem is I am not sure if this pump will solve the "slosh cup" issue. It appears to have a plastic housing around the pump where return fuel is pumped back near the intake. I posted pics in the other thread 90's Z28 pump as in tank pump
viewtopic.php?t=25038

Do you have an opinion on that pump from the pictures or should I plan on putting some sort of additional structure as a "slosh cup"

68roadster · Post by **68roadster** » Mon Feb 12, 2007 8:28 am

Sorry, I should say I am planning a TBI with 4 injectors and from Autonomics to go on a 350ci chevy with less than 400 hp using the latest and greatest MS hardware and software.

renns · Post by **renns** » Mon Feb 12, 2007 1:31 pm

Looks like a nice unit. Is that white plastic housing sealed aside from a couple small fuel transfer holes? Does it sit right at the bottom of the tank?

68roadster · Post by **68roadster** » Mon Feb 12, 2007 1:47 pm

It appears that the fuel strainer attaches to the hole at the bottom which sits at the bottom of the tank. I know next to nothing about this type of fuel pump, but it might work.

I heard from someone that there is a general chevy mb called chevy talk that is cross generation. Maybe I can find someone over there that can tell me about this. (yet another mb registration process)