HAVE TO CRANK SEVERAL TIMES TO GET IT TO START FUEL PRESSURE IS ZERO THEN PUMP KICKS IN WHEN KEY ON AND PRESSURE STARTS TO BUILD IF YOU BUMP IT 3 TIMES IT WILL START EASIER BECAUSE FUEL PRESSURE BUILDS
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Re: FUEL PRESSURE DROPS WHEN PUMP STOPS.HARD TO START
The fuel pressure check valve in the electric fuel pump has failed, you will have to replace the fuel pump, it is in the gas tank, also replace the filter at the same time or the warranty on the new pump will be voided.
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That could be caused by a few different thing's . One would be a fuel pump static pressure check valve ,located in the fuel pump module . The way to test this is to hook - up a fuel pressure gauge , turn the key on an off several times , to build fuel pressure . Then let it sit to see if the fuel pressure drops . If it drops you need a new fuel pump module . Did your mechanic use an after market or factory fuel pump ? Another cause could be an engine sensor going bad . Have to have a scan tool hooked up to check sensor data .
A common cause is a faulty check valve in the pump. The check valve prevents fuel pressure from draining back into the tank. The pump gets power from the relay for only 3 seconds during crank which would not be enough if the fuel line has zero pressure. You could cycle the key on and off a few times and probably start it quicker if that is the problem.
Have the fuel pressure checked after sitting overnight.
install pressure gauge and watch when key is turned off to see if pressure drops to zero if so bad drain back valve in fuel pump replace it or deal with it or could be cheap aftermarket pump and has hard time building unnecessary pressure to open poppet valves between before fuel injectors
No such thing on your car. The temp sensor tells the computer what the engine coolant temp is. If it were faulty you would get a check engine light. I would have the fuel pressure checked before and after you crank the engine. The pump relay provides power to the pump when you turn the key on to recover some of the lost fuel pressure after the car sits. The one way valve in the pump is supposed to prevent the pressure from dropping. If the fuel pressure drops to zero it could take some time to crank the engine enough to get it back up.
Could be fuel pressure loss. The fuel pump is supposed to hold pressure when the engine stops. If it falls to zero, you would have to cycle the fuel pump relay a few times to get it back up to start. I would check the fuel pressure first.
Your car is fuel injected and has a fuel pressure regulator valve that allows fuel to return to the tank, one sure sign that the valve is bad is that it allows all the fuel pressure to return to the tank so you must crank and crank which in truth is not what gets it going. You attempting to start it multiple times is turning the fuel pump on for @ 30 seconds. Untill you have the valve tested try turning the key to on, when the pump stops running (whirring or light buzzing sound) turn the key off and back on again. After a few times the pressure should be built up enough to start the engine.
If the engine has to be turned over a number of times before starting it may be fuel pump related, more overly the check-valve within the fuel pump. If this has failed (or leaks back) the fuel system will need to come to pressure before the engine will start. I'd check your fuel line pressure when running you should see @ 40PSI or so; once shut down the system should hold pressure; if it drops off to zero then you know where the issues lyes.
I hope this may have helped.
My 98 Cherokee was the exact same. I used to have to turn the key back and forth 3 times and then it would start. Otherwise it would just crank and crank for a while and then start. Pretty embarrassing! Took it to the dealer and they said that my fuel pump was losing pressure. I changed the fuel pump and I don't have to prime the pump anymore.
i have had the same problem.the solution is the fuel pump! i know you got pressure and it runs so how can it be the fuel pump? the pump is losing its prime you are getting pressure just no volume thats why its crank off crank off the system is priming itself again kinda like a weedeater or similar motor fuel is there just not enough of it to the injector To check this hook a pressure gauge turn on key turn off key release fuel should be plenty but if tis just a few drops thats it hope this helps