how do i get my xj to start on first crank or two? any advice would be awsome!..its a 97 se with 150 000 miles new pluges wires cap and rotor.jeep runs great!..but rolls over about 10 times before it starts i hate it! also new batt and alternator..thanks again!
The gas in your fuel rail might be vaporizing after you shut the jeep off. causing it to have to crank over a bunch of times. Try turning the key to the position just before start and let the fuel pump fully prime the system before engaging. Maybe even cycle the key a few times.
I'm not suggesting you live with it like this, but it may help you figure out if that is your problem.
If it's doing that from a cold start, it might be the check valves in the fuel lines (located in the fuel pump).
You can "borrow" a fuel pressure tester from AutoZone or one of the other parts-box stores to check your fuel pressure levels and figure out whether it's a leaky injector, the check valves, etc.
I've been having the same issue for about a year now from a cold start, and figured out the check valves are bad. So now I just kick the ignition to where it has power and runs the fuel pump w/o cranking the engine a few times (10-15sec each time) and when I crank it over it starts fine.
Sooner or later I'm going to drop the tank and replace the fuel pump, which "should" fix the problem. But until then it's not an issue, just an annoyance that I've gotten used to.
Next payday I'm going to install new injectors, throw some spark plug insulator boots on them, and wrap the fuel rail in insulation to cut down the effect of engine heat.
***WARNING: I drink and post.***
I had the same issue, I put up with it for years by turning the key three to four times listening to the fuel pump each time (don't turn the engine over, just turn the key). You can tell when it is primed by the sound of the pump. Then it will start.
If this works, the check valve is bad. This can also be confirmed with a fuel gauge. If pressure bleeds down when jeep is not running, the check valve is no good causing you to have to prime each time you start the vehicle.
With mine, replacing the Cam Position Sensor in the distributor restored the firing issue. I had replaced a failed crank sensor at about 150K, the cam sensor must have been going for awhile, as it crank times started increasing. I replaced the cam sensor at 163 and "voila". As others have suggested, use OEM parts. I ordered two crank sensors from 2 different Asian suppliers, (they were cheap). The plug on one was incorrect, the others wire was a bit short, placing undo strain on the plug. (BTW, the Asian supplier was most apologetic and promptly refunded my money. Imagine how great our country would be, if our elected officials were half as responsible as an Asian seller of $10 auto parts.!!!?)
The check valves (there are two of them; the primary one is on the fuel pressure regulator and a secondary one can be found on the fuel pump itself) are part of the fuel pump assembly on 95.5-2001 vintage 4.0 XJs. When a check valve starts to fail, it can reduce fuel pressure to a point where an extended cranking time is needed to start the engine. It is a very common failure. I experienced it on my 99 at around 75K.
A good (and simple) first step in helping you troubleshoot this problem is called “the poor mans prime”
1. Turn key to ON position (do not crank the engine!)
2. The fuel pump will energize and run for about 2 seconds. Be sure to wait until it stops running.
3. Turn key to OFF position
4. Repeat above steps 1-3 two more times
5. NOW crank the engine over
If the engine starts quickly and cleanly after performing this procedure, you may have a check valve issue. If it starts and runs poorly for a few seconds, it could also be a leaky fuel injector resulting in the fuel pressure leaking down and the subsequent stumble upon startup is the engine clearing the excess fuel that has leaked into the cylinder because of the faulty injector.
Also be aware that a bad battery can give you starting symptoms as well. Have your battery load tested (any parts store will do this for free) if you have any doubt; your XJ does NOT like low available battery voltage. Be sure battery connections and posts are CLEAN.
Some troubleshooting tips for extended crank times. You will need a fuel pressure gauge. Many parts stores will rent you this tool inexpensively.
*Hook up fuel pressure gauge on the schrader valve on the fuel rail under the hood
*Start engine and bring to normal operating temperature.
*Observe fuel pressure gauge. Normal operating pressure should be 49.2 psi (plus or minus 5 psi)
*Shut engine off.
*Observe pressure on gauge. Pressure should not fall below 30 psi for five minutes.
If pressure falls below 30 psi, it must be determined if a fuel injector, a check valve within the
fuel pump assembly, or a fuel tube/line is leaking. An adaptor tool/hose normally included with the fuel pressure gauge can help you with this. Consult the manual that comes with the fuel pressure gauge and the Factory Service Manual for your year XJ for more information on this exact procedure, but here is basically how it works:
*Turn the engine off and immediately clamp the fuel line at the adaptor hose. Watch the pressure gauge and see how long it takes to lose pressure.
*If the pressure remains at 49 psi for an extended period of time then the problem is in the tank – most likely a check valve. If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky fuel injector.
**Note. Where check valve is suspect, a quick loss of fuel pressure is often the fuel pressure regulator check valve and a slow loss of pressure is often the fuel pump check valve. But keep in mind that either or both check valves can be to blame.
You can limp a check valve problem along indefinitely if you like, as it doesn't mean the fuel pump itself is going to fail. Perform the “poor mans prime” before cranking to speed up your starts. However, if you have a check valve issue and want to resolve it, it is recommended that you replace the entire fuel pump assembly for two reasons. First, you have to drop the gas tank to access the assembly. Secondly, with two check valves, replacing just the fuel pressure regulator where one of the check valve resides may or may not resolve your problem; remember there are two check valves; the other check valve is part of the fuel pump.
The fuel pump assembly consists of fuel pump, fuel pressure regulator, fuel gauge sending unit, fuel gauge float, pickup filter and pigtail wiring harness. If you do replace the fuel pump assembly, purchase a high quality assembly. Know this….you do get what you pay for here. Some cheap aftermarket assemblies have been known to fail prematurely. I personally prefer Bosch fuel pumps as they manufacture the best fuel pump assemblies for the XJ. Carter is my second choice. Airtex is my least favorite choice and I will not recommend or install them. A search will show you why.
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche Without "data", all you have is an opinion!
As other posts have said I am leaning toward the check valve myself. Have a 2000 XJ. After it has been sitting for awhile, like overnight, I have to crank it for a bit to start. When I am out running errands it starts right up. Checked my fuel pressure, specs call for 49lbs + or - 5lbs, and mine was a steady 49lbs. With the Jeep off pressure would drop so I think I have the check valve issue myself. Thing is that it is on top of the fuel pump and I can not justify going in there to replace just that. So I just turn the key on and off 3 times or so and it starts just fine.