Air intrusion in fuel lines

Fuel pump is good and fuel filter is good, also replaced the fuel lines. Still no idea why my truck won't start. Tank is also sealed. Gas flows all the way through filter. Tank had fallen off not too long ago and I had to replace it, wondering if an open tank while running would cause any problems too. Getting tired of trying to diagnose problem.

My car has 180000 miles.
My car has a manual transmission.

Experienced mechanics share their insights in answering this question :
Hi there. This situation has happened to me before with my buddies Ford 7.3 Power Stroke. Although the process is slightly different, you might want to watch this video as it shows how to prime the fuel system on these Ford diesel engines. Unfortunately, this is the only solution to this all too common problem.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

When air bubbles or vapor are present in your diesel fuel delivery system, fuel injection is delayed. This delay happens because the fuel cannot be injected until the air and vapor are compressed to the correct fuel injection pressure.
Check the suction side of the fuel supply system. Your fuel supply system is between your fuel tank and the transfer pump. A leak in this area can lead to air getting sucked in by the fuel system. Lastly, a failed injector combustion seal is another common cause of why air gets into your fuel system.
Air bubbles in a fuel line can lead to stalling, hiccuping or refusal to start. Keep your fuel lines free of air to help keep your car running smoothly.
Some diesels are prone to air-locks when the fuel line is disconnected such as during a fuel filter replacement.
There should be a hand pump in the diesel system for priming your injector pump and removing air from the system. If you don`t remove the air/prime the system you will most likely not get the engine running.
The intercooler is connected to the air intake of the engine with hoses. As the piston slides to the bottom of its stroke, the combustion chamber fills with air due to the opened intake valve. This is known as the intake stroke. The intake valve(s) close and the piston pushes the air up toward the cylinder head.
The fuel tank may build excessive pressure due to a blocked vent. This could cause fuel to spray on occupants or bystanders when opening the fuel cap, potentially causing injury. Additionally, if an ignition source was present, this could create a risk of fire, causing injury and/or damage to property.
For optimal performance, a diesel engine`s primary need is a continuous supply of clean fuel. A symptom known as “airlock” occurs when this flow is interrupted by an air bubble, causing the engine to shut down and refuse to start.
For optimal performance, a diesel engine`s primary need is a continuous supply of clean fuel. A symptom known as “airlock” occurs when this flow is interrupted by an air bubble, causing the engine to shut down and refuse to start.
It is not only used when changing the delivery pump or the fuel filter but also when replacing high pressure pumps or other system components. Bleeding the low pressure side prevents, among other things, defects to the high pressure pump which can occur during filter change without manual bleeding, for example.
When you run low on diesel, your fuel pump might send air through your fuel system instead of gas. If that happens, your vehicle will shut down and not restart until the air is removed. This is called “bleeding” the fuel system, and depending on your machine, it can take several hours to complete.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I have a 1981 e-350 with dual fuel tanks the p.o. added a third tank and 3 electric fuel pumps along with sepparate gauges and swi
ANSWER : The switch you are referring to is vended with the required electrical and fuel schematic (I just looked in the box) that answers your installation question. If you want an advance view, here is a link as well. Yes, you need a return line and just refer to the aforementioned link. If you are retrofitting back to OEM, I strongly encourage you to buy the original Factory Service Manual (FSM). There are lots of details attending this system and obviously it is difficult to recount it all here. The FSM will make your life much easier and you can then make sure your installation is perfect. Alternatively, YourMechanic can dispatch a certified mechanic and perform the whole retrofit and check out if you desire. Just request and schedule a generic service such as fuel pump service and the mechanic will come to your location and estimate the parts and labor required. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Fuel pressure
ANSWER : Hello,
You may want to try checking the fuel pump relay. The relay wires should have ground on two wires, power on one wire and switched power on another wire. To activate the fuel pump your ECU actually connects one of the ground wires to complete the circuit and send power to the fuel pump. If the wires all have power running through them, then it is likely you have a faulty relay. The wire coming from the fuel pump is the other ground wire. I would recommend having an expert from YourMechanic come to your location to diagnose your wiring as this can be very difficult and time consuming without the proper wiring diagram.

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How long and what is the process to replace a fuel pressure sensor?
ANSWER : A professional mechanic would require roughly 5 hours. (If just the regulator is replaced that takes about 1 hour). Some parts, as noted below, cannot be re-used, you need a precision inch pound torque wrench, FSM instructions (and TSB updates if applicable; procedure was changed in 2007 for instance) and the system has to be bled when done.

Below is partial list of steps, copied and pasted directly from the service manual:

1. Disconnect battery and put protective material in front of the charge air cooler (CAC) or damage to the CAC may occur.

2. Remove air cleaner assembly.

3. Disconnect the oil drain tube from the crankcase vent oil separator.

4. Loosen the air cleaner outlet tube clamp and detach the air cleaner outlet tube from the turbocharger.

5. Remove the bolts, the crankcase vent oil separator and the air cleaner outlet pipe as an assembly.

6. Remove and discard the crankcase vent oil separator press-in-place gasket. (To re-install, tighten to 13 Nm (115 lb-in).

7. Disconnect the PCM electrical connector (BE SURE BATTERY IS DISCONNECTED FIRST!) and retainer. Disconnect the in-line electrical connector and position the engine wiring harness on the engine.

8. Remove the pushnuts and the glow plug module heat shield.

9. Disconnect the high-pressure fuel injection pump electrical connector and detach the retainer from the glow plug module bracket. Disconnect the glow plug module and the exhaust gas recirculation temperature (EGRT) sensor electrical connectors, detach the wiring retainer and position the wiring harnesses aside.

10. Remove the nut and position the ground strap aside. To install, tighten to 13 Nm (115 lb-in).

11. Remove the engine wiring harness bolt. To install, tighten to 13 Nm (115 lb-in).

12. Remove the heater supply tube nut. To install, tighten to 13 Nm (115 lb-in).

13. Remove the bolts and the glow plug module bracket. To install, tighten to 13 Nm (115 lb-in).

14. Remove the nut and position the transmission fluid indicator tube aside. To install, tighten to 8 Nm (71 lb-in).

Warning: Do NOT disconnect the glow plug electrical connector before dislodging the seal from the valve cover or the wiring harness may be damaged.

15. Using an appropriate tool, dislodge the glow plug wiring harness seals from the valve cover.

16. Disconnect the glow plug electrical connectors by pulling on the glow plug wiring harness tee above the seal. Remove the glow plug wiring harness.

17. Remove the nut and position the crankcase ventilation drain tube aside.

18. Disconnect the wiring harness retainer from the valve cover stud.

19. Disconnect the wiring harness retainer from the generator bracket.

20. Disconnect the A/C pressure switch electrical connector. Position the harness aside.

Warning: Do not bend or flex the heater supply tube or damage to the tube may occur.

21. Remove the stud bolts, bolts and the valve cover. Remove and discard the valve cover gasket. To install, tighten to 9 Nm (80 lb-in).

Warning: Contact with exposed fuel injector wiring, if energized, may result in electric shock.

Use care when working on or around energized fuel injector wiring. Fuel injector wiring supplies HIGH VOLTAGE to operate the fuel injectors of course, you disconnected the battery though.

22. Disconnect the fuel rail pressure (FRP) sensor electrical connector.

Warning: Fuel injection equipment is manufactured to VERY precise tolerances and fine clearances (think space shuttle). To prevent fuel system damage, it is essential that absolute cleanliness is observed when working with these components. Always install fuel system caps on any open orifices or tubes.

23. Remove the FRP sensor. To install, tighten the FRP sensor in 2 stages.

Stage 1: Tighten to 7 Nm (62 lb-in).
Stage 2: Tighten an additional 40 degrees.

24. Bleed the high-pressure fuel system.

If you feel like this job may be too overwhelming or run into any issues, consider YourMechanic to get it done. One of our mobile technicians can come to your home and replace the fuel pressure sensor at your own convenience.

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1983 toyota corolla 69,000 miles. Not sure if it’s a problem with fuel lines, fuel tank, or fuel filter.
ANSWER : If the exhaust smells like gasoline, the fuel mixture is either way too rich or you have a weak ignition system that is not burning the fuel efficiently. You can pull spark plugs out to check them and if they are wet or black they may be fouled and this can cause very rough running, misfires and stalling. Consider hiring an experienced technician like one from YourMechanic who can come out for a closer inspection of the vehicle in order to run a few tests and offer a more personal diagnosis of your stalling and drivability concerns.

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Just replaced my fuel pump but its not getting any power tested fuel pump relay and fuel fuse both good tested the wires all good.
ANSWER : You need to look at the theft light on dash to make sure it comes on and goes off when you turn the key to the on position. If light comes on and stays on then your theft system is causing the fuel pump to not be engaged. I recommend you check the theft system and then scan the computer for theft system codes. You may need to reprogram the keys to work or you have an bad sensor for the ignition key in the steering column.

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Carb not getting enough fuel I don’t see it in the window n I put new fuel pump n lines on and another carb on it but same proble
ANSWER : Hi there. Unfortunately, I think Jay is correct here. Usually when you see air bubbles in the filter, it’s due to a pick-up issue or debris in the fuel. If the gas tank is the original one from 1980, it is very likely that the tank is filled with excessive debris. You might want to drain the fuel tank, and inspect it for damage.

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I have a truck that won’t run and is not getting gas to the engine. Fuel pump is running, have a new filter and new fuel pressure
ANSWER : Hi There,
It sounds like you may have a clogged fuel injector or potentially a faulty injector that is fried internally. I would suggest testing them if you have access to a multi meter. Disconnect the injector from the electrical connector and set your multi meter to Ohms mode and measure the resistance of the injector. After testing all injectors, compare the resistance. They should be the same or very close. If they are not, they will likely need to be replaced.

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Car won’t start after sitting for 14 months
ANSWER : Hi there. Check the fuel pump to see if it is energizing, and check the fuel pump relay to see if it is clicking when you turn on the key. If the relay is not clicking, then remove the relay and check to see if there is any power with using a test light. If there is power, then swap the relay out with the horn relay and see if the relay clicks.

If the relay clicks, then the relay went out and needs to be replaced. If the relay still does not click, then check the ground circuit for continuity, which is the feed circuit to the fuel pump. If there is no continuity, then the fuel pump needs to be replaced.

If you need further assistance troubleshooting your vehicle, then seek out a certified technician, such as one from YourMechanic, who can come to your location to determine why the car is not starting and suggest the necessary repairs.

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