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MQ3-45B pump looses pressure every 10 seconds

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I have a 1991 Chevy s-10 4.3 fuel injection will crank fine every time runs for around 30 seconds then dies need help troubleshooting


Do you know if the pump continues to run beyond the first 30 seconds ? Are you loosing fuel pressure ?

Jul 23, 2014 | 1991 Chevrolet S-10

1 Answer

What can kill the fire to fuel pump


The fuel pump is controlled by the ECM which receives a signal from the fuel pressure sensor . When the pressure is reached the sensor signals the ECM and the power to the pump is reduced / stopped until the pressure falls . Have a fuel pressure test done on the manifold to check fuel pump--pressure regulator and filter. Run fault codes to check for correct venting around the canister.

Mar 03, 2014 | 2000 Dodge Durango

1 Answer

My Wel-Bilt 1hp Shallow Well Pump #109231 is continually recycling (every 30 seconds). It looses about 10 pounds of pressure as soon as it reaches 40 lbs. There are no obvious leaks anywhere. The tank...


It is hard to figure out but you have what I call a water bound system. There is no air in your pressure tank. The easiest way to resolve is to drain the tank, let it fill with air, then turn on the pump, problem should be resolved for a while. There is a device that regulates the amount of air in the tank, that has failed or needs adjusting.

Nov 03, 2013 | Plumbing

1 Answer

I have a 1993 Pontiac transport van and it will start up and run for 5 or 10 seconds and die


You may want to do a fuel pressure test to start. The pump could be defective. The fuel pressure should hold steadily and not decline with the pump off. If the fuel pressure falls, you either have a fuel leak, stuck injector, faulty fuel pressure regulator, or a bad fuel pump check valve. If the pressure holds at the correct spec, note the pressure as the engine runs and then dies. If the guage shows correct pressure, you can then move on ruling out the fuel system.

Apr 03, 2013 | 1993 Pontiac Trans Sport

1 Answer

Compressor runs fills tank but then it wont keep the pressure, won't restart to keep pressure above requested pressure. I have to let it seat for 1/2 hour to restart again


Most likely problem is the tank fill check valve. The most common way a a tank will loose pressure is by leak-back at the check valve. This also makes it hard to start because it leaves the tank pressure on the pump head instead of letting it bleed off. The motor will only restart after the tank pressure is bleed off to a low level, reducing the back pressure the motor will have to overcome. Leaking can be heard at the pressure switch, where the air is normally bleeds off over 10 seconds or so after the motor turns off. A defective check valve will continuously leak down at the pressure switch unloader valve instead of bleeding out in just 10 seconds. The check valve is an assembly that is largely hidden inside the tank. It just looks like a large hex nut where the filler tube from the pump enters the tank. Removal usually means first removing a smaller hex/barb/connector where the smaller relief line ties into the big nut. Inspection of the check valve will easily reveal whether this is the problem.

Oct 20, 2012 | Craftsman 3 gal. Air Compressor, 1.5 hp,...

1 Answer

Will start if i put gas down the port/carb seems to have fuel press at test port,,changed the rotor/dist. cap,don,t allway have fuel press may be the knock sensor ?shutting it down. it was hard startind...


sounds like fuel pump relay. next time it want start pull the ecm bat fuse for a few seconds see if it will crank then. knock sensor will not cause this. ecm bat fuse it works the fuel pump relay,fuel pump,injectors,ignition system an the pcm. also the oil pressure switch will shut down the fuel pump if oil pressure drops below recommended pressure . check the connectors on these things that not loose or corrioded.i think you will find the fuel pump relay is what this relay is the problem. this relay maybe in dash or under hood in the relay box.

Dec 11, 2010 | 1997 Chevrolet S-10 Pickup

2 Answers

Hard to start after it sits u have to keep cranking for at least 30 t0 45 sec


When you turn on the key the fuel pump relay causes the pump to run for one second to bring the fuel manifold presure up. If the vehicle has 'sat' for a long time, this one second is not long enough and so the engine is struggling to get enough fuel to fire. Try turning the key on and off every couple of seconds for about a minute, then turn the key to the start position. The engine should now start. Do not touch any controls such as the throttle, the computer will take care of all this.

Mar 17, 2010 | 2001 GMC Jimmy

1 Answer

When starting my truck it will turn over for about 10 to 20 seconds and then finally start but when it does it idles really low for about 5 seconds or so and then it finally comes up to normal idle. I...


You are loosing fuel pressure when the engine is not running. The common failures are the fuel pump and the fuel pressure regulator. The way to test it would be to put a fuel pressure guage on it and a shut off valve. Then turn the key on and see if the pressure drops. If it dose then turn the key on again and then shut the valve. Depending on wheather the pressure drops again or dose not then you will know which one is loosing the pressure. Also about the low Idle the IAC motor may have carbon built up in it. You will need to clean out the throttle body real good with carb and choke cleaner. At the top of the throttle body in the bore you will see a small passage you need to spray lots of carb cleaner in there to clean out the passage.
Hope most of that made since.

Oct 13, 2009 | Chevrolet Silverado 1500 Cars & Trucks

1 Answer

When starting car, takes 8-10 sec to turn over.


Do you mean 8 to 10 seconds to START? Turn over means the engine is turning or cranking BUT starting is when the engine is actually running. I think you might have a fuel problem like your loosing your prime. Turn the key off wait 15 sec. then turn the key ON not cranking it repeat this (3x) if the car starts immediatedly your fuel pump is loosing its prime or the fuel pressure regulator is leaking.

Jul 13, 2009 | 2001 Isuzu Rodeo

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