engine acting strange, to lean because of fuel pump problem??

My mustang was running perfect but my gas tank was almost empty before we went on holiday.

Came back home, tried to start but it did nothing because of the drained battery.
Normally it is hooked up to a charger but didn't want to leave it unattended for 3 weeks.
So hooked it up to a booster and it started but sounded really strange.
Range was only 2 miles. So I went to the gas station with another car to fill up some cans. Tank was filled half after that but the strange sound stays.

According to my AFR it runs lean.
Checked the injectors and fuel rail and they seem to be ok.
Checked the fuel filter (didn't have a spare to replace it) but nothing really dirty coming out of it.
Couldn't test pressure but according to my SCT the pressure drop is at idle between 38-40

I don't get any DTC codes about this.

I'm using the GT500 Dual pumps.

Could there be dirt in the pump itself?

Drove it around like this hoping it was only a minor dirt thing and maybe it would go through but it didn't. Engine got a bit hotter that usualy but it went 216F max.

Any advice on what to try?

Fully charge the battery.
All kinds of odd things happen when the battery is marginal on these spanish oak processor cars.

RED09GT said:

Fully charge the battery.
All kinds of odd things happen when the battery is marginal on these spanish oak processor cars.

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Its charging right now. So I really hope that really was the problem.

I thought that when the booster would be connected it would have had enough juice to overcome the problem.
But maybe it doesn't work that way

Could be bad fuel or moisture build up in the tank.
Check the injectors with a volt meter and if you want do diy cleaning on the injectors.
Clean the spark plug and check for vacuum leak.

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Start with the battery. If these cars don't have a full constant charge the processor can do crazy things.

Charging the battery didn't solve it

Although I think it sounds slightly better.

We cleaned out the injectors and sprayed them with some brake cleaner. Same for the fuel rail.

The coils are working and the sparks are clean and good.

Will try and replace the fuel filter tomorrow.

Fuel pressure is somewhere around 41psi before startup. Goes to 75 while cranking.

If you have a tuner and an aftermarket tune, try reloading it.

3 weeks is not that long for a car to sit so that really should not have been an issue.

Maybe bad ground/corroded ground or moisture build as mentioned.

[emoji848] disconnect the vacuum line that is connected to the fuel pressure sensor on the fuel rail...see if theres fuel going into that line which it shouldnt

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Gh0stRep0rt said:

check for vacuum leak.

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Do you mean this on the fuel lines or in the air intake?

philip_mustang said:

Do you mean this on the fuel lines or in the air intake?

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Air intake
The vacuum lines that are connect to the top of the valves cover.
Also since you said that your fuel pressure goes high, check the fuel pressure sensor which seat on the fuel rail and has a small vacuum line that if you follow it it attach to another line that one side goes to the back of the intake manifold and the other one connect to round thing againts the fire wall which connect your break master cylinder.
Thats small line shouldnt have fuel in it... if it does than that sensor is bad.

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Reloaded the tune but that didn't help.

No fuel in the vacuum line attached to the top of the fuel sensor.

Fuel filter replacement changed nothing.

Checked al the vacuumhoses from the valvecovers to the oil seperators and back to the intake. Found no leaks.

When it comes to vacuum the only thing I also noticed yesterday was that the nylon hose going from my E-Force to my Boost/Vac Gauge got loose. The rubber adapter to attach the hose to the sensor has ruptered. I removed the nylon hose and closed it all up. Can't use the gauge right now but the OEM closing screw is back in its place right now.
But off course it didn't solve this issue

Check you alternator voltage when you are driving normal at at WOT. I believe you should see around 14 to 14.5 V. Your alternator might be acting up.

I have had some strange problems occur when my alternator started going bad. I have one of these in the cigarette plug above the radio. For the price it's very accurate. Many of the reviews - people have tested the accuracy.

Amazon.com: DROK Digital Voltage 10-170 ℉ Temperature Monitor Tester Multimeter Car Motorcycle Battery Voltmeter Thermometer Detector: Industrial & Scientific

The alternator is brand new. Is installed about a month ago.
Its a 200amp powermaster.

I always keep an eye on the voltagemeter on my SCT and its mostly somewhere between 13.5 and 14.2V

So alternator was only installed a month ago, def don't rule it out then. Almost all now are remans.

I am not familiar with the powermaster but not many people have had success with aftermarket alternators on these cars. Even though it is new, I would not rule it out as a problem.
How about the battery-how old is it?

I have just over a year on my Oreilly lifetime warranty alternator....but then again, I don't have any large power consumptions ( yet). Receipt is in the glove box. Now that I have praised her, she will probably go crazy on me.

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RED09GT said:

I am not familiar with the powermaster but not many people have had success with aftermarket alternators on these cars. Even though it is new, I would not rule it out as a problem.
How about the battery-how old is it?

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Tell me about it. Its my 4th alt in 2 years.

First one PA 150amp performance died. Replaced by a 200amp PA of which the shaft broke off resulting in a damaged timing cover.
The new PA perf gave up after 1 year so now the shop advised me the powermaster one.

I don't have a lot of power consumptions so the 200amp might be to much. Only extra stuff I have are additional cooling mods for the intercooler and transmission. No big stereo and all the lights are leds.

But never had issues like this.

Battery is 2 or 3 years old. Its already a bigger one with 72Ah 680A.

Unfortunatly my tank is completly filled up. Otherwise I would take out the fuelpump to check it out. Tried to suck some fuel out but the hose doesn't seem to go deep enough. Got to go and get me a smaller hose.

@slackinoff: that is indeed the risk you take when your praise a part

Although the AFR Gauge says that the engine is running lean the exhaust smells like fuel. This gives me mixed feelings about really running lean.

So would it be possible that an injector isn't working good (stays open) and that the engine gets to much fuel instead of to few?

The Lambdasensor is only installed on 1 side of the exhaust so it can only read one side of the engine.

Took out the injectors and brought them to a shop for testing.