Too cold for car to start? dropping fuel pressure?

[jongreene]

To start my car has been sitting since friday. I went to start my car yesterday and she ran for about 3 minutes and quit, after that it will run for about 10 seconds and shut down. I was able to jump out while it was running for its 10 seconds and look at my AFPR gauge.The gauge will jump up, hold pressure for a second, fall, then the car stalls. Temperatures have been around 20-25 during the day and around 15 at night, so is it just too cold for it to run or what?

 

[twicks69]

Your gas line is more than likely FROZEN.

ADD GAS. Then retry.

 

[95blackGsTurbo]

Your gas line is more than likely FROZEN.

Or not. Gas' flashpoint is -97*. It COULD freeze at 32* but would have to be insanely deluted with water and if it only sat for a few days its very unlikely. My car sat for a month in -20* and started right up for me.

 

[jongreene]

I was thinking the moisture could be frozen too but if thats not it what else could it be?

 

[95blackGsTurbo]

Takes more than a few days for gas to separate in a sealed tank.

 

[jongreene]

Yeah.....what else could it be?

 

[robs90tsi]

Takes more than a few days for gas to separate in a sealed tank.

Unless theres a leak somewhere, like the filler neck, gas cap seal, etc.

 

[95blackGsTurbo]

Set a pint of gas outside in an open container and wait for it too freeze, you'll be there a while.

 

[oldman]

1. Does the fuel gauge drop off before the car shuts off or at the same time?

2. What was the gauge reading while running?

 

[jongreene]

Gauge reads about 20 psi and then drops before it stalls.

 

[oldman]

Gauge reads about 20 psi and then drops before it stalls.

What is your vacuum reading?

 

[jongreenway]

nice name.

 

[oldman]

nice name.

I would like to hear you say that again when you get to my age.

 

[twicks69]

Set a pint of gas outside in an open container and wait for it too freeze, you'll be there a while.

Agreed. My background is Chemical Hydrogeology and Environmental Geology. I deal enough with BTEX components to understand their chemical and physical properties. Especially in conjunction with water. You do have to remember that the specific gravity of gasoline is lower than that of water, hence making gasoline a "floater". If you have a considerable amount of moisture in your tank, it is definitely possible that you can freeze a fuel line. I have seen it many times before.

Unfortunately, our gas tanks are not always sealed systems, along with the stock fuel lines. There is considerably less surface area to deal with in the fuel line itself, causing a greater chance for failure. Even if you have a couple inches of frozen fuel line, you are dealing only with a volume of 0.3in^3 per inch (using 5/16" ID).

I was not meaning that the gasoline had frozen, but that the moisture in the fuel system froze in the fuel lines themselves.

_______________________________________________

Back to topic:

Have you checked your spark plugs yet?
Which fuel pump are you running? How old is it?
How old is your fuel filter?
What fuel modifications do you have done to your car?
How old is your car battery? Have you tested it?
Is your fuel pump hard wired to the battery?


What have you tried to fix the problem so far?

I look forward to your response!

 

[jongreene]

Spark plugs=new.
Fuel pump= walbro 255 less than 2 years old and wired to battery
Fuel mods= pump and afpr
Fuel filter= less than 2 mo. old
Battery= dont know how old but it was tested and good.
All ive tried to fix it so far was put some fuel anti-freeze stuff in the tank.

 

[Dsm78]

Maybe this will help. It's straight from the service manual... Start engine and run at curb idle speed. Disconnect the vacuum hose from the pressure regulator and clog the vacuum hose end. Measure the fuel pressure. (Non-turbo 47-50 psi at curb idle) (Turbo- M/T 36-38 psi at curb idle) (Turbo- A/T 41-46 psi at curb idle) Now measure the fuel pressure when the vacuum hose is connected to the pressure regulator (Non- Turbo 38 psi at curb idle) (Turbo- M/T 27psi at curb idle) (Turbo- A/T 33psi at curb idle) It sounds like you are a little low on fuel pressure being that you are only at 20psi...Its not far off but its not right on either. Have you checked to make sure that your not loosing power to the fuel pump when it dies??? If your fuel pressure drops immediately after you shut the car off you could have a problem with the check valve in the fuel pump not closing. If the pressure drops off slowly I would look for a leaky injector.

 

[jongreene]

It wont stay running long enough.
Its supposed to get up to 40 this weekend so hopefully she'll run.

 

[jongreene]

OKay guys now I really need help. Sunday I got the car running, put gas in her and everything was fine. Monday morning drive it to work still no problems...after work I ALMOST made it out of the driveway and it dies. Same stuff,runs for about 30 seconds and dies. This time I notice a clicking noise coming from the console/ ECU area, everytime it clicks it'll rev back up. Is my ECU taking a SH*T or what?

 

[95blackGsTurbo]

Open it up and check leaking caps.

 

[jongreene]

Yeah I know to do that, but I want to know if this sounds like the ecu going bad?

 

[jongreene]

ECU's pooped. thanks for all the replys

 

[Dsm78]

Glad you got it fixed. Your MPI relay is probably what you herd clicking. The ECU was probably reseting itself causing the MPI relay to also reset.