1998 Jeep Cherokee Starting problems

Tiny
DWEBB03
  • MEMBER
  • 1998 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • MANUAL
  • 200,000 MILES
Every couple of days my jeep would not start. It would crank great and try to start slightly. I would wait 15 minutes and try again usually with no luck wait another 15 and try again, after cranking for three minutes and giving it a littlle gas while it was almost starting I am finally able to start it. Runs great after that for a few days same thing again. Take it to the shop mechanic says it has code for crank shaft position sensor he changes it. All is well for a week same thing again bring it back mechanic says code low voltage its the altenator replaces it. 3 days later same thing back to mechanic, puts on a fuel pressure gauge says it is slowly loosing pressure I think he said from 45 to 25 over a 4 hour period. He now says I need a new fuel pump not trusting him anymore suggestions?
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Tuesday, March 23rd, 2010 AT 2:40 PM

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Tiny
CARADIODOC
  • EXPERT
Next time this happens, stop cranking, turn the ignition switch all the way to off, not just to "run", wait a few seconds, turn the witch to "run", (you should hear the fuel pump run for one second), then crank the engine. If it starts right up, dropping fuel pressure may be the problem. GM has a lot of issues with pump pressure. Chrysler, hardly ever. Low pressure would be the result of a problem with the pressure regulator, and Chrysler has almost no problem with them either. They commonly leak on GM vehicles. You know; the ones they advertise on tv how good they are?

You will need a fuel pressure gauge to monitor pressure when the vehicle sits for a while. If pressure comes up to normal as soon as you turn on the ignition switch, that isn't the long-crank problem. If you see the pressure dropping over time when it is sitting, use a hose pinch-off plies to pinch the return hose from the regulator to the tank. It's the smaller of the two fuel hoses between the body and engine. If pressure no long drops, the regulator is leaking. That is an irritation, nothing more.
If pinching the larger supply hose stops the pressure loss, the check valve in the pump is leaking. Another unharmful irritation. Both of these are very uncommon.

The more common cause of pressure loss is a leaking injector. It can cause a tempoarily flooded-type condition but typically for only one or two cylinders. Your mechanic can remove the injectors with the fuel rail so they can be seen, then he will watch for signs of wetness on their nozzles over time.

Caradiodoc
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Tuesday, March 23rd, 2010 AT 4:55 PM
Tiny
DWEBB03
  • MEMBER
Is it that hard to look at the injectors myself I am mechanically inclined, just don't always have the time to do the work myself. How much leaking is too much? By irratation you mean if I turn the key on first and wait for the system to pressurise and then start the jeep instead of just cranking it right off?
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Wednesday, March 24th, 2010 AT 1:42 PM
Tiny
CARADIODOC
  • EXPERT
By "irritation, I mean it won't hurt anything if you don't fix the problem; it is just an inconvenience to go through an extra step to start the engine.

The procedure is not to simply wait for the system to pressurize, then crank the engine. You must turn the ignition switch to "run", wait a couple of seconds, then turn the switch all the way back to "off" and wait a couple of seconds before trying to start the engine. Each time you turn the switch on, the pump will run for only one second. That might not be enough time to build sufficient pressure for starting. That's why you have to turn it from "off" to "run" multiple times before cranking the engine.

On some engines, it is necessary to remove the fuel rail from the injectors, pull each injector out individually, reinstall them into the fuel rail, wait for the fuel to evaporate, then turn on the ignition switch multiple times to pressurize the system. On some engines, the injectors can be unbolted and pulled out while they're still attached to the fuel rail. Pressure should remain in the system. Any sign of wetness at the tip of the injector indicates it is leaking. They should remain dry.

Some injectors only leak when they are still hot. Sometimes they only leak when they are cold. If you see one leaking, you know it should be replaced. If you don't see any sign of leakage, you don't know for sure.

Caradiodoc
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Wednesday, March 24th, 2010 AT 5:07 PM

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