I was wondering if there are any potential problems running a high flow EFI pump, like a 255lph, to a stock TBI unit that is equipped with an AFRP. The return line from the TBI unit looks rather small. I thought it might be possible that a high flow EFI pump could overload the return-flow capacity of a stock TBI unit, thus causing abnormally high fuel pressure. Anyone ever experienced or heard of this?

I have this VAFPR

http://cgi.ebay.com/ebaymotors/NEW-G...Q5fAccessories

-Z

 

A 255lph pump can easily overwhelm the TBI unit. Would need to run 30 psi to keep the fuel delivery under control.

RBob.

 

You will need to replace the spring, the one that comes with that AFPR could not hold over 17psi steady.
Im using the one from TDS for 21psi.
http://www.top-downsolutions.com/pro...products_id=39

 

Alright, i'm glad i asked in that case. My problem is i really like the professional products line of external EFI pumps, and i would like to run a big block TBI w/90lb injectors. The smallest pump available is 180lph 45psi max, is that still liable to everwhelm a TBI.

Thanks for the heads-up on the VAFPR spring pressure.

-Z

 

For about a year now, I've had a Delco TPI pump pushing through my stock TBI @ 12 PSI, daily driven. It's certainly not a 255lph, but it pushes a good bit more than stock and I haven't had any problems.

 

several people here have been using tpi pumps on their either stock or modified tbis and they seem to run great in both cases. just be sure you get a genuine gm/delco unit. i think the p/n is EP241 (305/350 tpi fuel pump)

hth

 

I know of multiple cars running the 255l pump on stock TBI applications (with either stock spring or slightly stiffer spring, softer than the stock 454). However, it doesn't mean it is the safest, nor the best. The jury is still out for me. When my car fires this spring I will be using the 255l pump and slightly stiffer spring.

 

Shifty, I've heard the same, that some are running the 255lph pump with a stock TBI setup. But at the same time I know for a fact that one person that tried this could not get less then 24 psi with the regulator fully backed off.

I've also done some testing in this regard. However, the stock regulator has been removed and am running an external one. That and I can't find my notes on the results. Dimented posted some information on this also.

I've always wondered if the folks that are running the 255lph pump on a stock GM TBI unit without fuel pressure issues. That maybe the hose between the pump and out pipe within the tank is split. This is a common occurrence.

There has also been a batch of bad Walbro pumps. May have been one of those that the person had installed.

RBob.

 

Oh yea I am pretty nervous about it. Ha. I may have to look into a new regulator set-up. I have a couple of springs but I have long forgotten which is which other than judging by the gage of the coil. I think I have a stock 454 spring that came with my 454 VAFPR laying around. I will likely start with that and see if I can get the thing to run enough for me to get a decent tune dialed in.