EFI

[TheSilverBuick]

Re: EFI

I've thought about that but wondered then about fuel temperature and over pressurization of the surge tank. Any known issues with that type of plumbing? It seems simple enough.

[CTX-SLPR]

Re: EFI

The way I've seen the system working you have an inline low pressure, decent volume lift pump that pulls the fuel from the tank to the surge tank which then has a standpipe type arrangement that feeds back to the tank which will catch any air bubbles and pull them back to the tank. Then the high pressure pump feeds the engine and the return line from the fuel rail dumps back into the surge tank.
Fuel pump efficiency works roughly like this, more pressure, less volume; less pressure, more volume as the electric motors can do a fixed ammount of work and when its harder to run the gerotor it does it slower and you get less volume but it'll shove the fuel harder. I think you have to have a return from the surge tank to the main tank otherwise you'd build up the air in the surge tank and have to have an inline regulator to keep the lift pump from over pressurizing the tank. Hot fuel is less dense than cool fuel so it would in theory reduce your injector effectiveness slightly since you are getting less mol's of fuel per µs of injector pulse.
Disclaimer: Theory and speculation based answer, expert confirmation recommended.

[squirrel]

Re: EFI

That's how I did it, it's pretty simple...the return line from the surge tank to the fuel tank needs to come out the top of the surge tank, and the feed line to the high pressure pump needs to come out the bottom of the surge tank. Not much to it.

[TheSilverBuick]

Re: EFI

Ok, that sounds reasonable enough. I wonder about needing a regulator on the lift pump, since it should pressure up any more than a few psi if there is an open return line at the top feeding back to the tank.

Don't know how much of this falls into practicality/reality but if the lift pump line was near the bottom of the surge tank and the high pressure pump's pick up was at the bottom, then the rail return line near the top and the tank return line at the top, most the warm/hot fuel would probably go back to the tank......

Thanks for the input guys.

[squirrel]

Re: EFI

Should not be any need for a regulator after the lift pump.

[HoosierGTA]

Re: EFI

I'm not trying to jump ahead of anyone here but I'm 'bout to go to bed so I'll check this tomorrow. When the end of summer comes ,I'm pulling my 200,000 mile L-98 and going to put my 76 300 horse 350 ( not stock) with a older tpi intake . This will all be just a tide me over till I get the l98 rebuilt and probably stroked.None of that is the guestion since it think it will run fine (not a real radical cam) so since the motor is coming out anyways I thought I might run the tank low and see if the computer would compensate for the e85 . If it doesn't work no big deal it's going to be down for the winter anyways. Any predictions?

Bump and re-ask.

[dieselgeek]

Re: EFI

I don't think it's a good idea. I'm quite sure that the factory setup won't be able to compensate for e85 on it's own. The factory computer will freak when it has to compensate as much as 30% to achieve a stoich mixture. It'll probably run very lean and pop/backfire, also it'll probably not start or run very well since the cranking tables are fixed, based on coolant temp. I.e. you'll be starting the engine with 30% less fuel. Cold start will be nearly impossible.

-scott

[HoosierGTA]

Re: EFI

Even though I'm pulling it out ,I don't want to ruin it. 'nough said , thanks

[Mr4Speed]

Re: EFI

I've seen this discussed on some other boards and one problem seems to be that the older tpi multec injectors can't handle E85.

[fast man efi]

Re: EFI

I have a short document on my web site under technical downloads that discusses converting to E85 with EFI.

https://www.fastmanefi.com

[racingsnake440]

Re: EFI

Matt, have you got any pics of your Goldenrod setup?

What does anyone think of modifying a '99 up Chevy truck fuel pump to use in an older car? They have a reservoir around the pump so that the tank doen't need any baffling so it should just be a case of cutting a hole in the top of the tank and securing the pump.

[squirrel]

Re: EFI

I think most of the newer pumps are like that, I worked on a couple later mopars that had a similar setup. That 99 chevy truck pump is very tall the way it's installed originally, the tank has a large bulge at the top for it. One for another type of car lays at an angle, so it's not as tall, although the pump assembly is about the same overall size.

The pumps with the reservoir are interesting, I've taken a couple of them apart. The pump has 3 holes at the base, two intakes and one exhaust, one intake is connected to the sock at the outside, the other to a sock in the reservoir, so it draws fuel from the main tank into the reservoir, then draws it from the reservoir and pumps it out to the engine.