white2000xj

hey all, did some searching, and wasn't able to find any helpful info.

issue i'm having: hard starting / over crank

what i've done so far: complete tune-up, plugs, wires, cap, rotor, pick up coil

i cleaned out the throttle body, but the issue was there before i did all this, and i was thinking it would clear it up, but it didn't. the old spark plugs were .030 worn out when i took em out.

No CEL

i've had 2 other xj's with this same issue (never looked into it), they were both '99's. Mine is a '98 classic

any help will be appreciated, thanks everyone!

macgyver35

Give us some specifics:

Does the engine crank very slowly? Or...
Does the engine crank at normal speed but for an abnormally long time before it starts?

If yes to the first question, your starter is going or you have bad electrical supply to it. Bad connections / weak battery / bad ground(s) / etc.

If yes to the second question, I'd suspect crankshaft position sensor or maybe a weak coil. Weak coil could also be wiring/connection issues. It could also be lack of fuel pressure in the rail, which could mean failing pump, bad filter, etc.

bnkk

Try primming fuel pump three or four times (key key on wait sec off) and if it starts fast you have a fuel pressure leak usually injectors but could be pump check valve

tjwalker

You're going to have to explain this further. But if it is an "extended crank time before starting" that you are referring to, a fuel pump assembly check valve is high on the suspect list. Here is more.
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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.

JeepingDan

X2 I'd like to know if this makes any different condition.

white2000xj

Thank you for the responses and help, everyone!

Quickly, my battery voltage is ok, i replaced it a week ago (for different reasons)

And yes, it just takes an extended crank to start the engine. Once started, it runs fine. Only thing I do notice, when I start it for the first time in the morning, and begin driving away, it does sputter for a minute, or so, then clears up.

Thats about it, other than that, plenty of good power.

Again, thanks for the help, and thanks for the list of testing procedures, tjwalker, i'll be doing that first thing on monday.

chereveco

I Have a 2000/2001 XJ Sport, just replaced fuel pump, for a "Carter" one, after that It started with this issue, checked again and founded the little pipe that connects the pump with the pump housing with the rubber parts torn, replaced for a used one, tested and started to show the problem intemittent, gonna check the pressure regulator, before going to injectors.....

chereveco

Continuing with this mistery...

1- Removed the little pipe and replaced it with a piece oh hose. Problem continues...

2- Checked injectors, and they are still fine, cleaned them up, but Problem continues...

3- Final option==> To buy the hole replacing part... Every thing that goes inside the fuel tank will be replaced. Already ordered the parts....

Dredwolf

But I am following this thread closely also.

Finally got a decent 8.25 to replace the D35 rear on my 1999, and was going to start the swap this past Sunday. Got stopped by a dead battery even driving it up to the garage. Load tester showed the battery was failing, so I replaced it. Alternator tested good, but now my 99 XJ is hard to crank unless you pump the gas? Once it cranks, its stumbles and smells like its running rich, then levels out.

Printed the troubleshooting steps above, but does the need to pump the accelerator point towards something obvious? Trying to get this XJ moving before the $$ (and motivation) get diverted to another "random life disaster" aka marriage/job/kids/bills, and trying to avoid "replacing everything" too.

Thanks!

chereveco

I forgot to advice, my problem got resolved once I replaced the hole pump body ( filters, pressure regulator, etc ).

After a while check engine light came back in, now it says "small evap leak",....

Replaced fuel cap, for a Mopar one, but still the same.......

Who can it be now?