Also, do not forget that many late model OEM apps use a PWM controller to drive the fuel pump only as fast as required to relieve stress and wear on the pump; they spin the pump just fast enough to deliver the correct volume and pressure at the injectors for a given load criteria. Some even control the fuel pressure via pump speed.

OEM apps with deadhead setups also tend to use pulsation dampers up near the injectors to even out the pressure given the uneven on-off-on fuel delivery of the injectors which is more pronounced in a deadhead setup.

A setup with the regulator at the tank and "deadheaded" rails can be prone to vapor locking after you shut the engine off. When you shut off the engine and the fuel flow stops the fuel in the rails can boil off from heatsoak creating a hard start condition. Simply cycling the fuel pump won't fix this since there isn't a constant flow of fuel through the rails back to the tank as in a system plumbed with the regulator after the rails which will have fresh fuel go through the rails and displace the vapor. Granted, if the regulator is working properly it will hold the fuel pressure in the rails after engine shut off which is to prevent vapor locking. Once that pressure subsides then vapor lock can be a problem. Most OEM manuals I've seen specify that pressure at the rails be maintained for a minimum of 20 minutes after engine/fuel pump shut off to combat vapor locking from heat soak.

Even putting the regulator back at the tank will still heat the fuel, although not as much as running it through the hot engine compartment and rails first and then sending it back to the tank. Regardless of where you put the regulator by pumping the fuel you are adding heat to it. As long as the fuel can shed its heat through the tank to ambient air faster than you can put the heat in everything's OK; once you start putting more heat into the fuel faster than you can dissipate it you are on your way to overheating the fuel and creating a vapor lock condition which can not only strand you on the side of the road but can lead to fuel pump cavitation and damage.

Yep.. the OEM setup used the pulse dampner in the OEM fuel rail. When you switch to and aftermarket fuel log system you loose this item.

Good post, sounded very much like what Aeromotive told me today.

Steve
 

Do you have Bret's number at aeromotive?

Just call and hit the number (#2 i thing) for tech assist.. if you get someone else just ask for him.. Bret Clow

Tell him that jabbering guy from PHR sent ya.. He had lots of good info.

Thanks guys. I'm looking at a cooler of some sort to put in-line and possibly swapping to a smaller pump. In looking through Summit's online catalog, I have only found one that says it's for gasoline. It's a dual circuit unit ( http://store.summitracing.com/partde...5&autoview=sku ). I guess I could just tie one circuit to the other and get all six passes to cool the fuel. What would keep one that is made for a transmission or oil cooler from being used for gasoline instead? I would think that as long as it sealed it would be ok, but not sure if there is another reason for not having it listed on the Application list.


I think that it's possible to add a PWM output on the MegaSquirt controller that I am using. I'll see if I can figure out what I need to do to use it to slow a pump down, whether it is the one that I have or a smaller one that I replace it with.

I will save you the time calling Aeromotive. I spent hours talking to them two years ago.

1) Put the pump as close to the tank as possible.
2) Put the pump level with the bottom of the tank so gravity will feed it.
3) Use -12 feed line to fuel rail and make sure the filter is the -12 opening and not the -10
4) Use as big as you can for the return
5) Use a controller for the pump/pumps.
6) Insulate lines from heat.
7) Use a sump in the tank.
8) Return line needs to spray fuel into the top of the tank not into the gas. let it hit the side of the tank and run into the fuel so air will cool it.
9) Run as big a vent as possible.

IMO.....Most aftermarket pumps are not made for continious duty use on the street without a controller. Every drop of gas in your tank goes to the engine bay about every 12 minutes. That is where the heat comes from unless you have cavitation from some other reason. The pump will get loud from cavitation, fuel pressure will vary and the pump will eventually shut off and you will be standed until it cools or you put fresh gas is to cool it.

Most coolers can be used for gas.. here's a new one from Barry Grant that I'm looking at. Plumb it into your return line.

http://www.barrygrant.com/news/artic...oduct_005.aspx

The other one I'm looking at is this small fanned unit from B&M.

http://www.bmracing.com/index.php?id...bcat=28&pid=75

I would make sure it will withstand 50-60 psi. When you go into boost your fuel pressure goes up above 45psi.

I really don't think you will need a cooler with a controller. I have no problem with my car now.

2 bosch pumps
1 Aeromotive controller
-12 line to the fuel "Y" at the engine.
-8 return

FYI, the cooler should be installed on the *return* line and won't see more than a few PSI of pressure, whatever the backpressure is from the cooler back to the tank.

Thanks Steve. I like the idea of the fan on it to help push air over the cooler.

Thanks Turbo Duece. Are the Bosch pumps in tank units or do they make external ones also?

Good to know. I'll keep it in mind. Thanks.