Marks2000XJ

Does anyone have a probable cause where it takes a jeep two or three tries to get it started? I can hop in and put the key in and try and start it and it will turn over but it is like the first time it turns over, that just "primes" the engine. Then the second time it usually will fire right up. Sometimes it takes three tries but most of the time just two.

I don't know if this is an injector problem, spark plugs, fuel pump? Does anyone have the same issue or any ideas what is causing this? It is driving me crazy and I want to get it fixed.

macgyver35

Sounds like fuel pump to me. Try this...

Get in. Turn the key to ON but do not start the Jeep. Wait 5 seconds and turn teh key off. Wait 5 seconds. Now try to start it normally. See it fires up readily then.

Marks2000XJ

I will give that a try. What does it mean if it works? If it don't work?

luckyAD80

Subscribed. Mine usually just goes and goes for the first time but ALWAYS starts immediately the second time.

Radi

Fuel check valve is leaking, isn't keeping the fuel system pressurized when turned off. It's part of the fuel pump ***'y. It's harmless to leave as-is provided you don't mind turning the key twice to prime the system.

AzItaliaSS

+2 on this for me as well.

Gee oh Dee

Yep.

tylers89

Mine does the same thing, but only when it's warm. When it's cold it starts great!

tjwalker

The check valves (there are two of them; one on the fuel pressure regulator and another on the fuel pump) 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 a couple of seconds
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 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 one is on 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 unit; 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.

Marks2000XJ

"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."

I forgot to mention that part as well. After it starts up it idles rough for about 10 seconds until it clears the excess fuel. Revving up the engine (adding air basically) seems to clear the problem up quicker. Then it runs fine.

So it sounds as if I may have a couple of problems. Bad check valve (possibly two) and a bad injector/injectors.

Nice. The previous owner neglected the heck out of this jeep. Pisses me off. I have more money in it already than I will ever get back out. Looks like I am married to this one!

mike mike

On both ours the check valve is bad. So I turn the key to the on position and wait a few seconds (I time it to when the stereo comes on) and hit the key, starts right up.

Beacherboy

I may also have this problem - it sounds spot on to my 1990 Cherokee Wagoneer. To anyone who has rectified this issue - can some prices/sources for new checkvalves be posted - as well as a quick DIY instruction? Much appreciated!

xjboy14

Thats what was with mine a while back but i also need to replace my head gasket. Darn oil

Matt Uliano

i got a 98 xj only two previous owners and both neglected the crap out of it. ive already got more in than im getting back so its my wife now lmao. rebuilt the whole engine externally about to rebuild down to the head gasket. already deep, might as well go full restore!

OutbackOz

check your fuel pressure I suspect its the check valve recently replaced mine and fuel pump now I turn key on wait 3 secs for pump to pressurize the rail and start first time every time