Fuel Pump$700

[swalkers]

You guys are better than my mechanic :doh:

 

[TerraWombat]

Nah (well, maybe) - just a nerdy engineer that is probably overthinking something...

 

[heyhar]

Sometimes, the more you know, the more you realize just how much you DON'T know...

Ignorance (and a pocket full of cash to pay others to do stupid repairs) is bliss...

 

[Tim_MN]

The fuel pump is fine and will continue to run for years. My check valve checked out about 4 years ago.

Crank for 2-3 seconds, back off the key, and crank agian. 90% of the time mine starts on the second try. Having the Jeep start on the second try is cheaper and easier than having the fuel pump replaced or dropping the tank to do it yourself.

 

[O-Gauge Steamer]

The pump should come on when the ignition goes hot, wait a couple of seconds and then hit the key. My '98 also needs a check valve (anyone see a trend in the data?) and that is how I start it. Common problem with FI engines. My 72 Mercedes needs a pause between keying on the ignition and actually starting it. As the pump is bolted to the frame, you can hear it run up to pressure. Once pressure is there, it and the XJ fire right away.

 

[FlexdXJ]

I have been having some trouble with my '00 XJ lately. Mostly prolonged statups, it cranks for a while before it actually fires. I brought it into the mechanic and had the fuel pressure checked out. It was running at 47-49 psi and dropped down to 8 within 5 minutes after the engine was turned off. Looks like the electronics were ok as was the regulator.

I am assuming that I am going to need a new fuel pump, and probably before winter in New England.

However, my mechanic quoted me $700+ to have it done. Seems a bit high to me? Any thoughts on other fixes I can try for the mean time? Im going to try some seafoam to see if there is an off chance that might help.

Spend the $280 and drop the tank yourself. thats one job you really don't need a shop to do for you.

 

[joe_peters]

There was one (maybe two?) posts by a member/user of that after they put an inline check valve in their 96+ XJ the fuel dampner on the fuel rail popped apart.

After that I stopped recommending the inline check valve for 96+ XJs. Now, was that one (maybe two?) incidents just coincidental?

If it was mine, I guess I would safety wire the dampner so it couldn't self-disassemble. Or, option two, locate the BMW check valve that is installed at the pump. You would still have to drop the tank, but a heck of a lot cheaper.

No, I don't have the part number, but a search should turn it up.

 

[x99j]

the bmw check valve popped my fuel damper on my 1999 classic. i ended up getting a new module and and a newer fuel rail!

 

[birchlakeXJ]

The check valve is located on top of the gas tank and is part of the fuel pump assembly on 95.5-2001 vintage 4.0 XJs. When the check valve starts to fail, it reduces fuel pressure to a point where an extended crank 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) way to 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 a two more times
5. NOW crank the engine over

If the engine starts quickly and cleanly after performing this procedure, you may have the check valve issue. If it starts and runs poorly for a few seconds, it could also be a leaky fuel injector resulting in the bleed down and the stumble upon startup is the engine clearing the excess fuel that has leaked into the cylinder because of the faulty injector.

Some troubleshooting tips for extended crank times:

Hook up fuel pressure gauge on the schrader valve on the fuel rail
Start engine and bring to normal operating temperature.
Observe test gauge. Normal operating pressure should be 49.2 psi (plus or minus 5 psi)
Shut engine off.
Pressure should not fall below 30 psi for five minutes.
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. An adaptor tool/hose included with the fuel pressure gauge can help you with this. Consult gauge manual for more information on this 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 - possibly the check valve. If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky fuel injector.

You can limp a check valve problem along indefinitely if you wish as it doesn't mean the fuel pump itself is going bad. Normally, the check valve is replaced as an entire assembly as you have to drop the gas tank to access the assembly. Fuel pump assembly consists of fuel pump, regulator, check valve, filter. If you do replace the fuel pump assembly, purchase a high quality OEM style unit. Some cheap aftermarket assemblies don’t hold up and fail prematurely.

 

[heyhar]

Birchlake- Thanks for the excellect entry. Since you seem to be up on this, maybe you can answer this: Is the regulator on the newer setup after the check valve, or before it. The location of the valve relative to the regulator seems to be the detail that needs to be known, so we don't end up popping lines at the rail. Our two older XJs, '92 and '95, have regulators on the fuel rail, and our two '96s do not have it, so I'm assuming that it's in the pump/sender module. I'll guess that the regulator is the last device in the assembly, before the gas leaves through the line, but I'd like you to confirm this. Thanks!

 

[joe_peters]

Fuel pressure regulator/filter combo, sits on top of the tank: AIRTEX / WELLS Part # 5G1211

{#4798301, PR315}
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