WHEN CAR SITS OVER NIGHT IT DOES NOT WANT TO ...

1998 Mercury Mystique

Tiny

RMcPherson

October, 23, 2012 AT 10:52 PM

When car sits over night it does not want to start in morning. I have to pump the accelerator pedal continuously and it takes between 1-2 minutes before it begins to start. Once it starts it runs very good with no missing and will start throughout the day. Fuel pump pressure tests ok, pressure regulator new, CKP new, TPS new, IAC new, Relay ok, new fuel filter, injectors all clicking (no other test on them yet), Coil pack ok, spark plugs and wires ok. Fuel pressure does drop quickly when car is shut off.

FOUND 61 RELATED QUESTIONS

18 Answers

Tiny

saturntech9

October, 23, 2012 AT 11:04 PM

Do you have any codes in the computer?

Tiny

RMcPherson

October, 23, 2012 AT 11:08 PM

No DTC codes

Tiny

saturntech9

October, 24, 2012 AT 4:18 AM

That fuel pressure drop could cause the the fuel lines to bleed down all the fuel and cause excessive cranking and start time. Try this in the morning before starting it. Turn the key to the run position wait about 3 four seconds then turn it off then repeat do that about 5 times then start the car. Does it start better?

Tiny

RMcPherson

October, 24, 2012 AT 2:24 PM

I cycled the ignition switch 6 times allowing the fuel pump to pressurize each time then tried to start the car but it had no appreciable affect on accelerating the engine start time. As I press and depress the accelerator pedal I do get some backfire through the air intake at sporadic times.

Tiny

saturntech9

October, 24, 2012 AT 4:17 PM

Do you have a scan tool that can read live engine data?The next thing I would be looking at was coolant temp sensor reading when your starting it cold?You could have a bad coolant temp sensor.

Tiny

RMcPherson

October, 24, 2012 AT 10:13 PM

I have an CAN OBD2/EOBD scan tool but not one that will read live engine data that I am aware of. However, I had previously purchased a coolant temp sensor but had not installed it but went ahead and installed it. However, it did not make any difference regarding the cold start problem.

Tiny

saturntech9

October, 25, 2012 AT 2:29 AM

Just because you a new sensor doesnt mean its reading correct thats why I asked to read the coolant on the scan tool. Which engine do you have?

Tiny

RMcPherson

October, 25, 2012 AT 4:12 AM

GS 2.0L

Tiny

saturntech9

October, 25, 2012 AT 4:59 AM

Please do the trouble shooting I posted.

Tiny

RMcPherson

October, 26, 2012 AT 1:56 AM

Regarding the trouble shooting tests: 1. Everything checks out ok.

2. Fuel Pressure at idle = 32PSI; @ 2500 RPM = 32PSI (Spec is 27.5 to 33.5 w/Vaccum connected) (There is about a 6 PSI rise when I step on the accelerator quickly.)

3. Engine off cycle 4 times fuel pump pressure = 38 - 40 PSI; Fuel Pressure drop with engine off after 1 minute = 12 PSI.
Recommends checking the Pressure Regulator and Fuel Injectors for leakage. The Pressure Regulator is new and there is no leakage from it. I do not know how to test the Fuel Injectors for leakage?

Thank You

Please login or register to post a reply.

Fuel Pump Pressure Test
Fuel Pump Test Chevy Tahoe
Fuel Pump Replacement
Fuel Pump Replacement Ford Mustang
Fuel Pump Replacement Done Right
Code Read Retrieval/Clear Mercedes Benz