After sitting without running for a long while, sometimes in-tank electric fuel pumps won’t start.
After sitting without running for a long while, sometimes in-tank electric fuel pumps won't start. That is the case with a Dodge Grand Caravan that I own, which sat without running since mid 2007. So my question is, how can a person make that fuel pump run again, without removing it from the tank? It's not like such fuel pumps were not designed to be submerged in fuel … where there is NO OXYGEN to promote any rusting! Normally, when a person turns the ignition key to the run position, the electric fuel pump will run for a brief time (such as one or two seconds), then shut off. Bu
Experienced mechanics share their insights in answering this question :
Check the power supply to the fuel pump, at the fuel pump terminals (as close as you can get) to be sure that the circuit actually functions. If there is power to the pump, but no operation, it is possible the fuel has oxidized, turned to varnish and other compounds, and basically glued the pump "shut". Also, it is not just a matter of air in the tank (oxidizing the fuel) but also moisture in the tank. Over so many years, the pump could be sitting in water simply due to accumulated water from condensation. If the tank has lots of water at the bottom, if it is a metal tank you might even need a new tank due to the possibility of internal corrosion. Although I suppose you could figure out a way to "unstick" a fuel pump that has sat in oxidizing fuel, and possibly water, for so many years, it is not worth it on account of safety and reliability considerations. If there is power and the pump doesn’t work, I would install a brand new pump and of course very carefully inspect the interior of the tank being mindful not to blow it up. Use a low power LED light…don’t use a 120 volt trouble light around fuel or, much worse, around fuel vapors. If you desire that the pump be replaced by a certified mechanic and the tank be inspected, simply request a fuel pump replacement. If you have additional concerns or questions, by all means please let us know.
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Often it is, but any number of things can prevent an engine from starting. These include a bad fuel pump relay or control module, a blown fuse, a wiring fault, loose or corroded wiring connector at the pump, or even an issue with the anti-theft system.
The older mechanical fuel pumps had a diaphragm that would crack and leak after years of sitting and was often one of the first on a list of things to do when trying to get an old car going. The modern fuel pumps are electric but are still prone to gunking up as fuel degrades.
The most likely causes of this are leaky hoses inside the tank. Some fuel pump modules use clear corrugated flex hoses inside the tank. This hose is designed to stand up to fuel and can reduce noise from the fuel pump.
A difficult start could be due to a number of things, from a dying battery to a faulty starter. But if your vehicle has a hard time starting after sitting for just a few hours, it can cause an extra layer of confusion. When this happens, one of the most common causes is low fuel pressure.
There`s no such thing as an intermittent mechanical fuel pump failure. Any power loss, engine `choke` problems, etc. are being caused by something else. In a fuel injected engine, electric fuel pumps can fail intermittently.
Fuel pump failures tend to be sudden and unpredictable, with few symptoms to warn the motorist that trouble is brewing. And the higher the mileage on the vehicle, the greater the risk of a fuel pump failure.
Regular gasoline has a shelf life of three to six months, while diesel can last up to a year before it begins to degrade. On the other hand, organic-based Ethanol can lose its combustibility in just one to three months due to oxidation and evaporation. Tracking the age of the fuel in your tank can be a challenge.
Fuel pump failures can be caused by electrical faults, old age (wear) or fuel contaminants (dirt, moisture or bad gas). Fuel pump failures often occur without warning. Fuel pumps, injectors and pressure regulators are the three most commonly replaced fuel system components.
The basic operating system for an electric fuel pump is relatively simple. When the key is turned on, the powertrain control module (PCM) closes the fuel pump relay, which activates the fuel pump for about three seconds to pressurize the fuel injectors.
There is a reason gas pumps have an annoying habit of shutting off. Gas pump nozzles are designed with a device on the end that turn off the fuel flow when the gasoline runs back into it. This is a safety mechanism which prevents the gas from coming out and spilling when filling up the tank.
A: Possible causes: a marginal battery, a poor connection in the starting circuit or starter, a charging-system problem, or the battery is being drained while the car`s parked. If this only happens first thing in the morning, a weak battery or a drain in the electrical system are likely causes.
A few possible faults could cause this type of intermittent no start condition. The most common would be a battery, starter, battery cables, fuel pump, fuel injector, or a wiring issue. This type of failure indicates a fault that only occurs once the vehicle is hot and can be difficult at times to duplicate.
Can a fuel pump stop working and work again from time to time? – Quora. Yes! That could be a bad pump, bad wire, or even a bad relay. Intermittent issues are the worst to fix because you can`t figure out what if causing the issue unless it is happening at the time you try to fix it.
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the most relevant questions and answers related to your specific issue
After sitting without running for a long while, sometimes in-tank electric fuel pumps won’t start.
ANSWER : Check the power supply to the fuel pump, at the fuel pump terminals (as close as you can get) to be sure that the circuit actually functions. If there is power to the pump, but no operation, it is possible the fuel has oxidized, turned to varnish and other compounds, and basically glued the pump "shut". Also, it is not just a matter of air in the tank (oxidizing the fuel) but also moisture in the tank. Over so many years, the pump could be sitting in water simply due to accumulated water from condensation. If the tank has lots of water at the bottom, if it is a metal tank you might even need a new tank due to the possibility of internal corrosion. Although I suppose you could figure out a way to "unstick" a fuel pump that has sat in oxidizing fuel, and possibly water, for so many years, it is not worth it on account of safety and reliability considerations. If there is power and the pump doesn’t work, I would install a brand new pump and of course very carefully inspect the interior of the tank being mindful not to blow it up. Use a low power LED light…don’t use a 120 volt trouble light around fuel or, much worse, around fuel vapors. If you desire that the pump be replaced by a certified mechanic and the tank be inspected, simply request a fuel pump replacement. If you have additional concerns or questions, by all means please let us know.
I changed the fuel pump and truck ran great for 3 days. Now after 3 days, the truck dies. It will start running for a few minutes, then dies like before.
ANSWER : Hi there, thanks for writing in. I’d be happy to help. It sounds like you should disconnect the connector to the fuel pump and inspect it for any signs of getting hot. The female connections may be too loose on the fuel pump and lose contact after running and getting hot. If there are indeed any signs of problems, then I’d suggest replacing connector and adding dielectric lube to pins before installation. This should solve the problem, but if you continue to experience issues, feel free to reach out to us for help again.
1993 Ford F150 4.9 straight 6 fuel pump keeps running, won’t start, replaced relay and fuel pressure regulator, still having the same problem
ANSWER : Hi, thanks for writing in. You need to have the fuel pressure checked to see if the pressure is low. The fuel pump inlet screen may be getting clogged causing the pressure to drop off but the pump will continue to run. You may need to replace the pump if it is not producing enough pressure. If you have dual tanks then you may have a defective switching valve in center of vehicle on frame. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to test the system for you, and make or suggest any repairs as needed.
Replaced fuel pump. Car won’t start. 2002 Infinity I35
ANSWER : Hi there – the metal component you describe is a fuel check valve on the fuel return line. Its function is to maintain a small amount of pressure in the fuel system so that starting does not require the fuel pump to run very long before the engine will start. Having replaced the fuel pump and fuel filter, I would check fuel pressure while the car is running. This is to check the fuel pump relay for burned contacts that won’t support full electrical current to the pump, and for proper fuel pressure – a malfunctioning fuel pressure regulator could also restrict power and higher speeds if pressure is too low. I would recommend an inspection of the fuel system by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.
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.
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.
Odometer has lines, won’t start unless I put fuel in the intake. The fuel pump keeps running and doesn’t shut off? Seems like the truck wants to start.
ANSWER : Hi there. From the description you have provided, you’ve replaced the fuel pressure regulator, the fuel pump never shuts off and puts fuel in the throttle body, it runs until the fuel is gone, and the odometer has lines instead of mileage. This would appear to be a fuel control problem and communication failure.
Some possibilities are that the PCM (Powertrain Control Module) has shorted internally causing the fuel pump relay to be commanded continuously on, injector driver circuits are inoperative, or failed communication to the IPC (Instrument Panel Cluster).
This all needs to be confirmed through diagnostic procedures. I recommend having your vehicle’s fuel pump never shuts off, truck won’t start condition be diagnosed and repaired by a certified technician, such as one from YourMechanic.
New battery & fuel pump. Hours later car starts and shuts down 3X in a row. Finally it starts, 48 hours later, won’t start at all
ANSWER : Checking all the fuses was a good move. I would also want to put a scan tool on it and check for diagnostic trouble codes (DTCs) as well as seeing the data that the computer is seeing.
A fuel pressure test would be a good idea to verify correct pressure and so that you’d be able to eliminate that possibility. It should be 58psi on your Magnum.
I also recommend getting your battery tested (I know, it’s new, have it tested anyway) and be sure it’s charged to at least 75%. And yes, loose battery cable connections can result in electrical problems.
If you need some assistance with this, consider enlisting a certified mechanic who can perform the checks I’ve mentioned and diagnose your starting issue firsthand. The mechanic can then perform the necessary repairs once the problem has been isolated. Good luck.
My car won’t start, neither does my auto. Start. Sometime it might start if I jump it sometimes it won’t.
ANSWER : Hi there. There are a number of issues that will make a car hard to start. Everything from the electrical system to the fuel system to the actual starter itself can be the problem. Finding the root cause of a hard starting engine can take some investigation. Ignoring a hard starting issue can further damage the vehicle, which will often result in a more expensive repair. You might want to have a mobile mechanic complete a car is hard to start inspection so they can pinpoint the source of the issues you’re having and recommend the right repairs be completed.
