Miles-

Here is the situation, I recently purchased a 95 camaro that has a pretty built motor and blower but wont go into those details unless needed. Please bare with me as I am in over my head with this project but want to learn and would like to do everything I can myself. Anyhow the has a large fuel system the details will be posted below. I have some pictures of the engine bay and how the fuel lines are routed if that helps. What happens is when the car is driven in traffic or at long speeds for a time the fuel heats very quickly until the point it vaporizes in the rails and shuts down until cooling off.

-12 line form the tank forward with a -8 return line, stock plumbing removed from the tank and replaced with a big pickup line, through the top where the original plumbing was. Weldon 2010 Fuel pump (I think that's the number but it is 1000 gallons per hour), large particle filter before the pump and small particle filter after the pump. I don't remember off-hand the filter particle sizes. The feed line is T'd before the fuel rails so that each rail has a direct supply rather than the stock system that runs the fuel through one rail and then the other before returning it to the tank. Weldon adjustable fuel pressure regulator. There is no FMU, the stock computer has been re-programmed by Mike Morgan. Injectors are flow matched 50 lb/hr with the stock impedance. There is a Weldon "Dial-a-Flow" unit installed so the driver can regulate the fuel flow to not have the full pump capacity when not using the gas pedal. This Dial-a-Flow system is designed to limit the flow while maintaining the pressure.


Some of ideas which have been brought up are
1) there is simply too much heat under the hood and not enough ventilation to allow cooling, so maybe an aftermarket hood would handle this

2) The system was poorly designed, because the lines and pump are mounted to the left of the intake they are sitting on top of the headers in a poor position. I was told to relocate them. Unless I am missing something no matter how the lines are mounted they will be running across the headers at some point and will be getting heated in the same manner.

3) move the pump out from the engine bay and mount it in line somewhere under the car. Does the pump itself have sometype of a sensor which reads the temp of the fuel and could cause the system to shut down?

4) lastly the car has been tuned, but maybe after the engine temp hits a certain degree too much fuel is being pulled causing a lean condition

Sorry for the long post, like I said trying to learn and get a beast back on the road. Any help and input is apprciated.

miles

Dave89IROC

by reading that, the fuel pump is under the hood???????????


relocate it as close to the tank as possible, fuel pumps work best pushing, not pulling, so locate it to pull as short a distance as possible

slopokrodrigez

First of all, if the pump is outside the tank, it should not draw from the top. Second, as mentioned above. It should be as close to the tank as possible.

How do you know the problem is fuel related?

How is the tank vented?

Does the problem show up sitting in the driveway or must it be driven?

What happens if you pressurize the tank slightly like blowing a small amount of compressed air into a vent line?

Miles-

the pump is mounted underneather the car, close to the tank. However I just picked up the car over the weekend so I havent tested the above mentioned. I have emailed the previos owner to provide me with some answers. How can I tell if the tank is vented?

he told me when idleing or sitting in traffic this condition happens.

how can I also test the pressurized air into a vent line?
I apologize but I am not too familiar with fuel systems as you can tell, but apprciate the help as it is a great way for me to learn. I will post up more info when I have some answers

markinkc69z

You have over 100 gph circulating through your fuel system at light load. The chances are slim that the fuel is vaporizing in the rails as they are pressurized. More than likely you are experiencing fuel pump cavitation that is brought on by heat picked up by the fuel as it circulates then placed under a vacuum at the inlet of the pump. You have been given good suggestions already.
The inlet filter needs to be checked and cleaned if possible.
If all you have for a vent is the charcoal cannister, you're going to be in trouble with that pump and a hot blown combination. Any fuel consumed must be displaced with air at the same rate. Any restriction to ventilation can lead to pump cavitation.
If the pump is mounted low and you really have a 3/4" or -12 line coming out of the tank, then that might be okay for you. After the siphon is started then things flow pretty easily, but just running a pickup tube into a stock tank does not always get the job done. Our testing has show that a vortex can be started in a stock tank and allow the pump to draw air at high volume rates. Some Camaros may not be as susceptible to this with the more vertical tank orientation, but it is worth mentioning.
The real enemy is heat of course. Anything you can do to reduce heat transfer into the fuel system along its path will help. Wrapping the fuel system with a reflective/insulating material is a good idea around heat sources. Pump speed controllers reduce the tendency for the pump to cavitate by limiting the volume that is circulated. With an inline flow through pump that's really its only purpose. With your Weldon T-style pump the high performance, high rpm motor can get pretty hot, and that's not good for long life. The heat has nowhere to go with a T style pump.
As you mentioned that it occurs in traffic I would say that you have a heat radiation problem in the engine compartment, beyond what will be absorbed from the fuel rails. Consider rerouting the fuel lines away from radiant heat sources, or protecting them from it.
Run your tank as full as possible.
Open your gas cap after you experience a problem and listen for a tell-tale hiss of air. That will let you know that your tank ventilation is inadequate. Then try driving the car with the cap loose and see if it helps.
Charcoal cannister filters can usually be replaced, as they can get dirty and restrictive. With your combo though, I would really put at least a -10 vent in the tank.

Miles-

I ran the car today for over a half hour, in stop and go conditions as well as ideling for 10minutes. I had the hood off of the car, figuring if heat was a problem this would get the most airflow I could. the car was fine with no issues, and you could see the heat coming off of the engine pretty well. I guess I can now figure heat has been the main culpurit, besides getting a vented hood and relocating some of the lines any other tricks to keeping this thing running a little cooler? what do you reccommend to shield the lines with by the way? Thanks for your help with this matter