Starting Problems

Sep 30, 2005 12 Replies

I have a 1998 Jeep Grand Cherokee, and for about two weeks now its taking alot longer to start, normally it will start right up within the first crank, but now it will crank over 5 to 6 times before starting... What could that be?



I have Brand New spark plugs, that was the first think I replaced...

It will start up great if you turn it off then start it again, but when you let it sit for about a hou, it will be hard to start again, It is hard to start about 90% of the time, Could you help?

Possibly a battery getting weak. Have it load tested and if it's getting weak replace it before you wake up to a dead battery in 20 degree weather!!!

Good Luck! Jim Smith

McNick did pass the time by typing:

Fuel pressure bleed off. Could be the regulator or the valve in the fuel pump is letting the rail pressure drop. Figuring out which one is not easy without the tools for shutting off the supply lines.

Stick a fuel pressure gauge on there and see what it says. (an old R-12 low side gauge makes a good tester since you can tape it to the windshield)

In the meanwhile turn the key on, wait for the fuel pump to stop buzzing then turn the key off, then back on again, after the buzz then start.

Info from manual

FUEL PRESSURE LEAK DOWN TEST

Use this test in conjunction with the Fuel Pump

Pressure Test and Fuel Pump Capacity Test.

Check Valve Operation: The electric fuel pump

outlet contains a one-way check valve to prevent fuel

flow back into the tank and to maintain fuel supply

line pressure (engine warm) when pump is not operational.

It is also used to keep the fuel supply line

full of gasoline when pump is not operational. After

the vehicle has cooled down, fuel pressure may drop

to 0 psi (cold fluid contracts), but liquid gasoline will

remain in fuel supply line between the check valve

and fuel injectors. Fuel pressure that has

dropped to 0 psi on a cooled down vehicle

(engine off) is a normal condition. When the electric

fuel pump is activated, fuel pressure should

immediately (1?2 seconds) rise to specification.

Abnormally long periods of cranking to restart a

hot engine that has been shut down for a short

period of time may be caused by:

² Fuel pressure bleeding past a fuel injector(s). ² Fuel pressure bleeding past the check valve in

the fuel pump module.

(1) Disconnect the fuel inlet line at fuel rail. Refer

to Fuel Tubes/Lines/Hoses and Clamps in this section

of the group for procedures. On some engines, air

cleaner housing removal may be necessary before

fuel line disconnection.

(2) Obtain correct Fuel Line Pressure Test Adapter

Tool Hose. Tool number 6539 is used for 5/16? fuel

lines and tool number 6631 is used for 3/8? fuel lines.

(3) Connect correct Fuel Line Pressure Test

Adapter Tool Hose between disconnected fuel line

and fuel rail (Fig. 11).

(4) Connect the 0-414 kPa (0-60 psi) fuel pressure

test gauge (from Gauge Set 5069) to the test port on

the appropriate Adaptor Tool. The fittings on both

tools must be in good condition and free from

any small leaks before performing the proceeding

test.

(5) Start engine and bring to normal operating

temperature.

(6) Observe test gauge. Normal operating pressure

should be 339 kPa 6 34 kPa (49.2 psi 6 5 psi).

(7) Shut engine off.

(8) Pressure should not fall below 30 psi for five

minutes.

(9) If pressure falls below 30 psi, it must be determined

if a fuel injector, the check valve within the

fuel pump module, or a fuel tube/line is leaking.

(10) Again, start engine and bring to normal operating

temperature.

(11) Shut engine off.

(12) Testing for fuel injector or fuel rail leakage:

Clamp off the rubber hose portion of Adaptor

Tool between the fuel rail and the test port ?T? on

Adapter Tool. If pressure now holds at or above 30

psi, a fuel injector or the fuel rail is leaking.

(13) Testing for fuel pump check valve, filter/

regulator check valve or fuel tube/line leakage:

Clamp off the rubber hose portion of Adaptor Tool

between the vehicle fuel line and test port ?T? on

Adapter Tool. If pressure now holds at or above 30

psi, a leak may be found at a fuel tube/line. If no

leaks are found at fuel tubes or lines, one of the

check valves in either the electric fuel pump or filter/

regulator may be leaking.

Note: A quick loss of pressure usually indicates a

defective check valve in the filter/regulator. A slow

loss of pressure usually indicates a defective check

valve in the electric fuel pump.

The electric fuel pump is not serviced separately.

Replace the fuel pump module assembly. The filter/regulator

may be replaced separately on certain applications.

Refer to Fuel Filter/Fuel Pressure Regulator

Removal/Installation for additional information.

McNick proclaimed:

Better than cranking 12-16 times?

Turn the key on without starting. Count to 5. Turn the key off, and then go straight to start. If that solves it, is simple fuel leakdown which is easier to ignore than cure. Other than that, when is the last time you had the vehicle serviced such as plugs, etc.?

McNick proclaimed:

Try replacing them with AC or Champion. Those chinese brands are crap even if they have fancy names.

McNick proclaimed:

Fuel drain down. Easily checked by turning the key on so the pump brings up pressure, then try the start.

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