Engine/Transmission (1994 - 1998) Advice on electric fuel lift pump options, FASS?

[Jerred]

I am one of few 12v'rs that have a fuel pressure gage on my truck. I also have the smaller 180hp pump. I am thinking that I would benefit from a FASS or similar system. My signature pretty much describes my truck. It seems like it runs really smoothly through about 2500rpm but becomes rougher at higher rpm's and when towing. I can usually suck the pressure down to 18-20psi on good throttle romps so I'm thinking I'm creating some timing lag. My pump is set at a hair over 16deg.



The three I have looked at are the FASS, AFS from Haisley and the Preporator. Anyone have good/bad experiences with these?



I was also wondering how to set up a system like that: remove the filter and stock lift pump or use the electric system as an additional prime for the stock system?



Thanks.

 

[BTighe]

i was considering this myself but was told that it isnt a benifit for us 12 valvers. i was told to spend the money elsewhere. then again running the amout of fuel you are it might be different with you.

 

[Jerred]

That's what I was thinking. I even have a relatively new lift pump. Maybe I need more timing with the amount of fuel I am running. Most guys in my hp range are up around 17-18deg if not more. Anyone know if that will smooth things out? It almost sounds like the truck starts missing when I'm really throttling it. Or maybe I'm just over sensitive and high hp trucks just sound meaner at WOT?

 

[BTighe]

ive heard that advancing the timing on the stock head gasket too much can blow it. do you still have to stock gasket on?

 

[Jerred]

No, I did a port and polish job on a new o-ringed head and put a . 010 over headgasket on it. I would also think that you'd have to jack the timing to the sky before you create that much more compression that you'd blow the gasket. but helping it out with lots of boost pressure from a large turbo or twins would certainly accelerate blowing a gasket.



My biggest complaint about the truck is that though it has lots of power, it just doesn't sound like most of my buddies with similar setups while you're really womping on it. Like I said, it sounds great to about 2500 rpm, which is about where the engine used to spool when it was stock and where I would assume the stock lift pump was rated for good fuel pressure. I did replace mine not too long ago but with the GSK, 191's, 0 plate and 370's, I'm trying to move alot of fuel, and I really think that lift pump can't keep up.

 

[Lsfarm]

Options

Jarred, you might try a few experiments before you spend $700 on a Fass or other monster fuel system.



I would suggest a larger set of fuel lines, so that your lift pump isn't fighting restrictions in the delivery system. Maybe a less restrictive fuel filter?? Our fuel filter housings have a lot of small passageways.



A method to give a few ideas a try would be to hook up a temporary fuel tank in the bed with much larger lines and run this through your lift pump to the engine. Then take it for a hard run and see if the 'missing' goes away.



As for 'sounding' the same as other trucks make sure you are compairing apples to apples, you have done a lot to your truck, are the ones you are comparing your's to similarly modifed?? I drive a lot of different trucks as I do transmission upgrades and suspension, exhaust, power modifications to my customers' trucks and every truck has a different personality, even those which should feel and drive identically.



Have you given Piers a call and asked him if you have reached the limits of your fuel system and what he recomends ??



Just a few ideas, hope this helps Greg L

 

[ABorchard]

I did calculations on the amount of fuel available to the P pump with stock transfer pump, filter and lines several years ago.

In order to max out the system with no return flow to the tank you would have to go over 300 mph while getting 2 mpgs. At 4 mpgs you could go 600 mph.

Get the idea?

 

[Joe G.]

Have you asked Joe Donnelly what pump he used on Sickly? The pitiful thing only made 800 HP on straight #2.

 

[Jerred]

GregL,

thanks, yeah that helps alot. I haven't talked to Piers yet about this specifically, though I think I've started to max out my alloted phone time with him on other matters! Nor have I talked to Joe D. But I'm getting to that. The truck is in the shop right now having a Trans oil leak fixed (I had problems with the big input shaft install from the git-go: bearing not pressed on far enough, my re-maned trans was shimmed incorrectly, cast iron tail housing seal hole not centered) and Ken at Imler Diesel found that since the trans was shimmed wrong the gears were wearing funny, and maybe causing so noise. And I may not have had the input shaft to the xfer case lined up correctly since I was trying to center the shaft on the seal so that I didn't pump all my tran fluid into my xfer case. Alot of my roughness and noise may be coming from drivetrain and not motor. So that may explain alot. I can't wait to drive it tomorrow.

I also learned a little tid bit at the last dyno day that I may not really have 370 injectors. In my quest to find a deal, I bought a set on Ebay for $299 and didn't call Cummins to verify the numbers on the box were 370's. Another guy at the dyno day said he bought the same ones (or it sounded very similar) and the numbers were for 340 or 350 injectors for another marine application. So my low numbers may also be attributed to that rather than fuel starvation. We'll see.

thanks for all the help guys. I think my money is better spent other places, is what it sounds like. Like a set of real injectors. A buddy of mine dropped a set of the Dynamite Stage 4's in and got 40hp on a very similarly fueled truck. I'll have to give Lenny a call... ... ...



Jarred

 

[Jerred]

Yeah, right on, that's what most 12r's are saying. Our system is pretty robust, which is why almost no one is using an electric system. Thanks, that makes good sense.