Running out of gas?

no164ford

Registered User
Ok here is the deal my wife just hade a baby and surgery so I an babysitting and can only get in the garge for five-ten min at a time:( . I got the SC running a few weeks ago it was running great for 1,000+ miles then at the track Wensday night it started to stall at an idle. after some research with the LM-1 I noticed that it would lean way out to 25.0-30.0 then stall so that meens it's running out of gas. I then drove it home 45 miles and as long as I kept it around 2K it run great but would still lean out under heavy load. got it home and the next day it seemed to run fine:confused: I left it idle for 20+ min and it was fine? so I cleaned the fuel filter out (it was kinda dirty) and installed a gauge on my fuel rail and it sees around 32psi with the vac line on and 38 with it off.

Took the car for a ride tonight it runs good till I get way up in the RPM's then it seems to die off a little like the outher night but not near as bad.

I can't get much time to look at the car for a few days and it is bugging the hell out of me:eek: so I was just seeing if anyone had any sugestions on what it may be let me know.

Tomarrow I was going to try to drain the gas out of it and put new in and if I can install my adjustable FPR and crank up the fuel pressure a little and see if that helps.
 
Run injector cleaner, REPLACE your fuel filter. If that doesn't fix it I would say your fuel pump is going. Is the car hard to start sometimes? Thats a good sign. FYI stock fuel pressure is 39 psi.
 
Tony8470 said:
Run injector cleaner, REPLACE your fuel filter. If that doesn't fix it I would say your fuel pump is going. Is the car hard to start sometimes? Thats a good sign. FYI stock fuel pressure is 39 psi.

I do want to get a new filter, I was thinking mabe the FPR is going bad? My batt light came on a few weeks ago but the car is charging fine 13.6+ I wounder if this has anything to do with it?

And no I never have a hard time starting the car.

I can also see with the LM-1 that my TPS and MAF sensors are working fine.
 
Perhaps, on the software side, disconnect the battery, and see how long the EEC's 'adaptive learning' is taking to lean out the A/F, again? (MAF curve?)
Spray the MAF with electrical cleaner? Vacumn hose leak? If you cut out the center post of your 70mm MAF it could run lean.

From TCCOA
The truth about MAF's
--------------------------------------------------------------------------------
In almost every thred you read about a problem, people are saying clean the MAF.. And there is a good reason for that. Here is a quick review of what happens when the MAF gets dirty and what happens to the car..

Maf sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, even potting compound from the sensor itself. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negetive) corrections at idle and learn rich (positive) corrections at higher air flow.

If the vehicle is driven at Wide Open Throttle (WOT) or high loads, the fuel system normally goes open loop rich to provide maximum power. If the MAF is contaminated, the fuel system will actually be lean because of under-estimated air flow. During open loop fuel operation, the vehicle applies Long Term Fuel Trim corrections that have been learned during closed loop operation. These corrections are often lean corrections learned at lower air flows. This combination of under-estimated air flow and lean fuel trim corrections can result in spark knock/detonation and lack of power concerns at WOT and high loads.

One of the indications for diagnosing this condition is barometric pressure. Barometric pressure (BARO) is inferred by the Powertrain Control Module (PCM) software at part throttle and WOT ( there is no actual BARO sensor on MAF-equiped vehicles, except for the 3.8L Supercharged Engine). At high air flows, a contaminated MAF sensor will under-estimate air flow comming into the engine, hence the PCM infers that the vehicle is operating at a higher altitude. The BARO reading is stored in Keep Alive Memory (KAM) after it is updated. Other indicators are Long Term Fuel Trim and MAF voltage at idle..

Im not sure if this is helpful to any1 but I thought it was worth a shot.
 
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Have you upgraded from the 30# injectors? You have a good list of mods, but I didn't see anything on the injectors. I would think if you still have the stocl injectors, they just can't keep up with the other mods you have. With the mods I had on my 91, it ran good, but with the same mods on my 89 with ported heads, it's running out of gas at WOT. Time to upgrade. :D :cool:
 
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Yes, that would agree with your car dying at the track. From bad plugs being leaned out. Looks like you got alot of money into those pistons. It would be a shame to burn a hole through one. I would try doing a 1st gear pull near your house. Hopefully it starts the same symptoms. Take the plugs out and look at them.
 
Sounds like a fuel problem. If you did a fuel flow test you probably would see that you're not moving enough volume of fuel.

Either your filter has become plugged bad, the fuel pickup is getting blocked, or the fuel pump itself is failing.

When a FPR fails, it lets excess fuel pressure through, not usually restricting it.

There is a fuel flow test you can do with the pump in the tank. Can't recall the specifics but basically you disconnect the fuel line at the rail and stick it in a bucket or container that has gallon or litre markings. Then jumper the test connector for the EEC to run the fuel pump and time how long it takes to fill the container with a gallon or a litre of fluid. That'll allow you to calculate the fuel flow.
 
The easiest way to diagnose the fuel system is to get a fuel pressue gauge that you can see while driveing the car. Do a pull, and if the fuel pressure drops off as the boost and RPM go up it points to the fuel pump. Of course any time you start having a lean problem, and you need to diagnose the fuel system, you replace the fuel filter before you even start the diagnosis. Cleaning the MAF, and resetting the ECU are also on the list of firsts, but not before reading the codes.
Just went and looked at your list of mods. You need a better fuel pump for sure, and injectors would be a good idea. It's great that you have that LM1 to help you out.
 
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I am sorry I need to add somethings to my list of mods. I have a 255bbl fuel pump and 42lb injectors. Ok here is what I have done so far I got the adjustable fuel pressure regulator installed and I increased the fuel pressure from 37-38 up to 40-41 a new gas filter drained the gas out of it and put in some fresh Snowco 94. The car still seems to do it I did not even think to clean the mas air flow I will do that first thing tomarrow. I think something has gone bad on the car, it run fine untill I got to the track (1,000+ miles) I have loged a good bit of AFR data before the probblem started and it was near perfict then all of a sudden bam it went crazy.
 
My car is doing similar thing as yours. It was fine and then Bam, one day it was not. Are you burning up fuel pump fuses too?
 
pablon2 said:
My car is doing similar thing as yours. It was fine and then Bam, one day it was not. Are you burning up fuel pump fuses too?

No not yet! I would look into a new fuel pump if I was you and mabe even check the wire harness on top of the fuel tank. They are noted to corade and short out there.
 
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