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Been away for some time, and now that I have a 3 yr old son I decided to get another solid car. It had to be Jag and 4.0. Two years ago I sold my 94 XJS to buy a car for my wife, but I missed it!!! And so the search began, found a super clean xj40 here in LA and I pulled the trigger. Here r some pics of this Jade Green beauty!
Hey Guys!!! Good to see some recognizable names again! Yes its a 94 VDP with polished wheels. Funny, the spare is matte. I think they look great on this car. Its a California car with no rust or paint bubbles anywhere. Always garaged and the previous owners had the front windshield tinted so the dashboard is perfect. No sun damage whatsoever. 67xxx is stunning and I cannot get enough of it. First thing I did was lube the door locks so that the door handles wouldn't stick.Im tending to some leaky hoses at the Power Steering reservoir, and trying to figure out why the heat is not hot enough. The other thing my friend and I are going to tackle is a hard start issue. Its fuel for sure, I think its the check valve since it starts right up if I start iit within a fews of stopping but if I let it sit more than a half hour it has to get fuel back to the rail before it starts. I have a gauge and T split set up so Ill get some readings in the next few days. BTW, does anyone know what pressure readings I should be getting?
Im tending to some leaky hoses at the Power Steering reservoir, and trying to figure out why the heat is not hot enough. The other thing my friend and I are going to tackle is a hard start issue. Its fuel for sure, I think its the check valve since it starts right up if I start iit within a fews of stopping but if I let it sit more than a half hour it has to get fuel back to the rail before it starts. I have a gauge and T split set up so Ill get some readings in the next few days. BTW, does anyone know what pressure readings I should be getting?
The low-pressure hose from the P/S reservoir to the pump is the most common leak point. Due to its proximity to the exhaust manifold, it hardens and loses its ability to seal around the nipple at the reservoir. See the photos at this link:
Power Steering Low Pressure Hose Leaks
Off the top of my head, the engine managment system manual says the fuel pressure should ideally be somewhere around 40 psi, but in the real world something in the mid-30s is common on these old cars. Here are some instructive posts from our good friend Bryan N at the Jag-Lovers forum:
Bryan N's Fuel Pressure Test Rig
The check valves do fail, but they work in conjunction with the Fuel Pressure Regulator (FPR), which also fails, so there's a good chance you need both.
There are two check valves that are part of the fuel pump canister in the fuel tank. Since the canister is no longer available new, and since replacing it is a pain anyway, I just added a new inexpensive inline check valve:
The FPR is is a common failure point. One easy test you can perform is to pull the vacuum hose, crank the engine briefly, then check for any wet fuel at the FPR vacuum hose fitting, which indicates the diaphragm has failed. This would not only mean the FPR cannot hold pressure, but that it is allowing raw unmetered fuel to be inhaled into the intake manifold. But even if the FPR passes this test, it probably is no longer holding adequate pressure in the rail and should be replaced. I spent the extra money for a Bosch, the same brand as the original unit, but other brands are available at lower prices. Some photos of the FPR are included in this album:
Another thing that can contribute to hard starting is corrosion on battery power connections and ground points. Since periodic cleaning of these is a necessary part of XJ40 ownership, I may as well get you started off with a college education:
Thanks for the great response! I ordered an aluminum check valve with 8mm fittings from ebay, so thats going in asap! Going to order a new FPR too since i think its going out too. Saved the day!
Yes, but there are times when I sit back in the car, after a meal and it wont start normally. I have to turn the ignition back and crank again. It has stumbled at times for a bit while it gets fuel going. Once the engine is going its fine. Im going to install a new FPR tonight. Whats the best way to depressurize the system before I remove the old FPR? Its a pretty straight forward process, im sure. Ill look for a wite up if there is one
Last edited by Brewtech; Jan 15, 2017 at 04:47 PM.
Whats the best way to depressurize the system before I remove the old FPR? Its a pretty straight forward process, im sure. Ill look for a wite up if there is one
On a 94, you can remove the oxygen heater relay (yellow base, firewall, passengers side) while the car is running. The engine will eventually quit and the fuel rail is depressurized.
Why not install a new fuel filter at the same time - they are cheap like borscht and easy to change.
Located just forward of the rear wheel, driver's side.
Larry
Last edited by Lawrence; Jan 15, 2017 at 07:02 PM.
Ok, installed the FPR and all looked pretty good last night. It started right up after 20 minute wait periods. Going to go outside in a few and start it from cold... crossing my fingers. Although Im pretty sure its good to go
Well spoke too soon😔. Everything was fine til this evening when I went to move the car and it didn't start on the first go. I went back out just a few minutes ago to try it and it did it to me again, so the inline check valve is going in along with a new fuel filter, unless the FPR I installed went bad on me. Hmmm I could just get a replacement and see what happens
Since the my IRS is still in the car, how tuff do you thonk
itll be to install my inline check valve?
Last edited by Brewtech; Jan 18, 2017 at 12:31 AM.
Since the my IRS is still in the car, how tuff do you thonk itll be to install my inline check valve?
I deliberated on where to put the check valve myself. I first installed in the flexible fuel line alongside the fuel rail, but when I dropped the IRS I moved it to just under the fuel tank. I couldn't tell any real difference in performance.
I think the best location for the check valve would be before the fuel pump, to keep the fuel pump primed. In the original design there are check valves before and after the fuel pump built into the plastic fuel pump canister or "module." But over time both of those check valves lose their ability to prevent backflow.
If you want to add a check valve, I'd recommend you put it in the flexible inlet line next to the fuel rail, where it's easy to install. However, know in advance that it may not be enough to overcome your slow starts. You probably have multiple issues affecting your starting. Here's the link to my check valve photos:
I would highly recommend that you clean all the battery power connections and grounds from the battery in the trunk to the starter and alternator in the engine bay and everything else in between. At the very least clean the battery terminals, the battery ground point on the right rear fender well, the firewall jump start post (disconnect both the positive and negative battery cables), the terminals at the starter and alternator, and all the grounds in the engine bay including the engine ground strap.
It might also be worth replacing the fuel pump relay, and also realize that your fuel pump is not as strong as it once was.
Lots of other things to consider, like cleaning the fuel injectors and replacing their filters and O-rings, cleaning the Idle Air Control Valve (IACV) and stepper motor, cleaning the throttle butterfly valve, cleaning the MAFS hot wire, adjusting any slack out of the throttle cable, checking the operation of or replacing the Coolant Temperature Sensor (CTS), etc., etc.
I deliberated on where to put the check valve myself. I first installed in the flexible fuel line alongside the fuel rail, but when I dropped the IRS I moved it to just under the fuel tank. I couldn't tell any real difference in performance.
I think the best location for the check valve would be before the fuel pump, to keep the fuel pump primed. In the original design there are check valves before and after the fuel pump built into the plastic fuel pump canister or "module." But over time both of those check valves lose their ability to prevent backflow.
If you want to add a check valve, I'd recommend you put it in the flexible inlet line next to the fuel rail, where it's easy to install. However, know in advance that it may not be enough to overcome your slow starts. You probably have multiple issues affecting your starting. Here's the link to my check valve photos:
I would highly recommend that you clean all the battery power connections and grounds from the battery in the trunk to the starter and alternator in the engine bay and everything else in between. At the very least clean the battery terminals, the battery ground point on the right rear fender well, the firewall jump start post (disconnect both the positive and negative battery cables), the terminals at the starter and alternator, and all the grounds in the engine bay including the engine ground strap.
It might also be worth replacing the fuel pump relay, and also realize that your fuel pump is not as strong as it once was.
Lots of other things to consider, like cleaning the fuel injectors and replacing their filters and O-rings, cleaning the Idle Air Control Valve (IACV) and stepper motor, cleaning the throttle butterfly valve, cleaning the MAFS hot wire, adjusting any slack out of the throttle cable, checking the operation of or replacing the Coolant Temperature Sensor (CTS), etc., etc.
Cheers,
Don
Thanks Don! This is definitely some good stuff to get in there and start working on it. This outta keep me busy for a bit, and I dont mind at all. Its truly a pleasure to work on this specific car. Thank you very much, BTW, is the flexible fuel line in the engine bay also 8mm?
Last edited by Brewtech; Jan 18, 2017 at 11:06 PM.
Alrighty. Just replaced the fuel filter because the old one looked old and it was an ACdelco unit which is not my favorite for a Jag. The threading on the the new filter didnt feel smooth on the outflow end but it screw down tight with no leaks. It has been starting pretty good and normal like in the last hour. Im at a restaurant having a late dinner, and Im hoping that when I go out it starts right up. Fingers crossed. Going to take the intake apart on my next day, even if all is well! Clean is always better
im back!
