I think I may found the answer to my question. I guess there is no power to the pump until I crank. I will try and check the pump by itself tomorrow. I always thought the pump would cycle before crank every time. I guess this car does not do it.

 

here's the procedure to check the fuel pump circuit, I would print it out and save it for the future. hope it helps verify the FuelPump. Next check is the Coil.


Fuel Pump Circuit Checklist



courtesy of: Doug Dwyer

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The purpose of this checklist is to explain the operation of the fuel pump circuit and provide an easy-to-follow fault diagnosis procedure. The only tools needed are a 12 volt test light and a length of jumper wire. I believe it to be accurate for all Series III XJ6 cars but some of the earliest cars may be different.


There are three main components to the system: the trunk-mounted, constant pressure electric fuel pump, a control relay, and a voltage directing diode pack. The system is so designed that the pump will operate when the starter motor is engaged and when the motor is actually running. For testing or cold-start "priming", the pump may be operated by putting the transmssion into "drive" or "reverse" and turning the key to the start position. This activates the circuit but the starter itself does not engage. Twelve cylinder cars, by the way, are wired differently.

The diode pack is mounted on the firewall and is easily identified by it's all-red color. The fuel pump relay is normally mounted right next to the diode pack but I've seen a couple of cars where the pump relay and the main relay have been flip-flopped. So, pay attention or you may end up checking the wrong relay. The fuel pump relay has the following wire colors: white, white/purple, white/green, and black.

1) First let's see if the pump itself actually operates. Remove the connector socket from the fuel pump relay. Determine whcih connector/terminal cavity is associated with the white/green wire (this wire goes directly to the fuel pump). Attach your jumper wire to a known good 12 volt source (the battery "+" post makes good sense) and touch it to the terminal of the white/green wire. You have now bypassed the control portion of the circuit and the pump should operate (you can hear it easily of you remove the spare tire cover panel or, better yet, use a fuel pressure gauge). If the pump operates, go to Step 2.
If it does not operate you have a wiring fault between the relay and the pump or a faulty fuel pump.

2) Reattach to connector to the relay. Now the fun begins. Get your test light out......

3) The black wire at relay terminal 85 should be ground at all times. If not, you have a wiring fault and/or loose ground point at the rear of the water rail. Trace out the fault or run a redundant ground.

4) The white wire at relay terminal 30 should have 12 volts whenever the key is "on". Voltage flows from the ignition switch and goes through the inertia switch. If there is voltage at the white wire, go to Step 5.
If there is not any voltage at the white wire then you have a wiring/connector fault, an "open" inertia switch (try resetting with the button jumping it) , or a faulty ignition switch ( try jiggling it).

5) The white/purple wire at relay terminal 86 and the white/green wire at terminal 87 should have voltage anytime the starter is engaged. Crank the engine and check for voltage at both terminals. If voltage is present at the white/purple wire (terminal 86) but not at the white/green wire (terminal 87) then the relay is faulty. If there is no voltage at terminal 86 when cranking the engine, then go to Step 6)

6) Locate the silver metal starter relay (furthest inboard of the four firewall mounted units), and, while cranking the engine, check for voltage at the white/yellow wire. If no voltage the starter relay is faulty and not sending voltage downstream to the diode pack. If voltage is present then locate the red diode pack and, again, crank the engine and check for voltage to the diode pack at terminal 3 (white/yellow wire) and at the diode pack at terminal 5 (white/purple wire).
If there is no voltage at terminal 3 when cranking then you have a wiring fault between the starter relay and the diode pack. If voltage goes is present at one side of the diode but not at the other, then the diode pack is faulty. Now, if voltage leaves the diode pack but terminal 86 of the fuel pump relay does not get any voltage then you have a wiring fault bewtween the diode pack and the pump relay. I might add that, in some cases, the diode pack may have proper continuity but an internal fault can cause a voltage drop with a resultant problem downstream. You'd need a voltmeter, not a test light, to properly check this.

7) Now, if the fuel pump operates when cranking but won't continue running as the engine starts to fire then we have to do some more checks. First, some background. There is an air flap inside the AFM which, when moved by engine vacuum as the engine starts, closes a micro-switch inside the AFM and powers up the fuel pump circuit. With the key "on", check for voltage into the AFM at the brown/slate wire. If no voltage then you have an open circuit between the AFM and terminal 87 of the "main" relay (next to the starter relay). If voltage into the AFM is OK then you'll have to simulate engine vacuum by manually moving the air flap inside the AFM.

Simply remove the AFM front air duct and, with the key "on", move the air flap and check for voltage at the pink/blue wire.If voltage is OK, then see Step 8.
If no voltage, then the internal AFM switch is faulty.

8) Voltage coming from the AFM goes to terminal 2 of the diode pack (pink/blue wire). If no voltage reaches the diode pack then you have a wiring fault between the AFM and the diode pack. Voltage exits the diode pack at terminal 5.

If voltage is not present at terminal 5 then the diode pack is faulty. If voltage leaves the diode pack (white/purple wire) but does not reach terminal 86 of the pump relay then you have a wiring fault between the diode pack and the relay.

Let me know what you find,
Jose

 

I saved, printed and started going through your checklist. When I directly connected the fuel pump it did power and made noise but no fuel. There was fuel going in but nothing coming out. I completely removed it and powered it up with the inlet in some water and nothing. So I am saying bad fuel pump. I am going to wait for your response just to make sure I am not missing anything before i go out and buy it.

 

The tanks on these are nortorious for rusting. They rust on the insides and then plug the pump. That would be my guess. Take a look at the tanks before jumping off into a new fuel pump or you may be right back in a couple of weeks or months.

 

How do i check the tanks? How hard are they to remove?

 

You can remove the rear tail lamps and then pull the fuel sending unit out and inspect with a flashlight. Or as the Brits say check the fuel tank with a "torch."

Removing the tank is a bugger in the driveway. The car must be raised incredibly high for the tank to slip out the bottom. It can be done, but you really need a lift for safety.

 

I doubt it's the fuel pump, but checking the tanks needs to be done anyway. But if they are not leaking, they are not bad, leave dirty, dirty enough, don't drop them.

Is there plenty gasoline in both tanks??

 

Yes there should be enough fuel in each tank. Just to make sure I put about 5 gallons in each tank. When I disconnected the fuel pump fuel kept flowing from the tube and I had to plug it to stop it. I also powered up and tested the pump in water and there was nothing.

I am wondering now if my passenger side tank is leaking since there is a drip out of the bottom. But it never did that until I added the 5 gallons and there was some spilling since the tube of the gas can was bigger than the hole so I dont know if it is the overflow. She is really becoming a project.

 

I replaced one of my tanks years ago, removing the old tank was not difficult, it was the amount of stuff that has to be removed before the tank...

If you have the Factory Service Manual, follow the removal procedure there.

But I insist that you have to do one job at a time, otherwise it gets very disorganized.

since you opened up the fuel system to atmosphere, and you did not de-pressurize the fuel system beforehand, the Fuel Cutoff Inertia Switch may have tripped, check the Inertia Switch continuously, it stops the fuel flow if tripped.

It's time to check the Ignition Coil. I will find the instructions to TEST the one you have and post them later.

Jose

 

You are right. I am not going to do anything with the tank right now. I will wait for the instruction on the coil.

 

Wow xb70.......havin looked thru the thread it looks like you got a real project goin there. Loads of good solid technical help from Jose and Ken as always.

Jim

 

hey Jim, haven't seen you around lately....


Here's the no start checklist:

1) Check for spark. You can buy a spark tester at any parts store which looks something like a sparkplug with an alligator clamp attached If you have one, fine. If not, remove a sparkplug wire and insert a screwdriver into the boot so that it contacts the terminal inside. Hold the screwdriver by the handle and position it about 1/4" from a metal part of the engine. Crank the engine over and watch for a spark to jump the 1/4" gap. If you have a spark, skip to Step 6. If no spark, see step 2.

2) Remove the coil wire from the distributor cap, insert screwdriver as mentioned above, and hold it about 1/4" from a metal part of the engine. Crank the engine over. If no spark, see step 3. If you DO have spark here then you have a faulty cap and/or rotor (spark is getting to the distributor cap but not getting to the sparkplugs). Remove the distributor cap and peek inside. Look for a burned center terminal, burned terminals to the plugs, cracks, or carbon tracks between the terminals. Inspect the rotor contact. If it's bad enough to create a "no start" you'll see obvious burning and/or disintegration of the contact.

3) If you don't have spark at the coil wire-to-distributor cap, then check for power getting to the ignition coil. Power here comes directly from the ignition switch via a white wire. If you have a ballast resistor, the wire will go there first. If no resistor, this wire will go directly to the "+" post of the coil. Remove the white wire and, using the test light, check for 12 volts with the key on. If you have voltage, see step 4. If no voltage, you have an open circuit. This can be confirmed by running your jumper wire from the positive battery post to the coil or ballast. If the motor starts, you have confirmed the open circuit and must now look for a wiring fault or ignition switch fault.

4) If you have 12 volts at the ballast you must check for voltage coming out of the ballast. Reattach the white wire. Using your test light, check the other ballast terminal. If the ballast is good, your test light will light up but no too brightly--- the ballast has reduced the voltage as designed. If the ballast is "open" (no continuity) your test light won't light up at all. If the ballast is OK (or you don't have a ballast) then, with the key still "on", check for voltage at both coil posts. If you have a ballast which checks good at both terminals but no voltage at the "+" coil post, then check for a wiring fault between the ballast and the coil. If you don't have a ballast you should have voltage at the "+" coil post if your wiring is OK, as mentioned earlier. You should have voltage at the coil "-" post as well. If no voltage at the "-" post, you have a bad coil.

5) If everything checks good so far but you still have no spark then you've got an amplifier problem or distributor pick-up problem. Testing of these items is beyond the scope of this checklist (requiring an ohmmeter) but do check the wiring from the amplifier for breaks.

6) You're here at this step because you've determined that your ignition system is working. Now we must check for fuel. Use extreme caution here. Be prepared for some spilled fuel and have rags, a small container, and fire extinguisher handy. Disconnect fuel supply hose at the fuel rail (at the rear of later "straight rail" cars and at the bottom of the early "loop style" rails). Some fuel may spill, have rags and container handy. A properly operating pump will produce about 34 PSI so, again, be ready ! Position fuel hose so fuel will flow into the container. (As an alternative to using a container you can hook up a fuel pressure gauge, if you have one. The usual method of attaching a fuel pressure gauge is to leave the supply hose connected to the rail but disconnect the cold start injector nozzle and use it's nipple on the fuel rail.)

7) Now, locate the fuel pump relay. It is mounted on the firewall right next to the red diode pack and has white, black, white/purple, and white/green wires attached. Remove the relay plug-in socket and determine which terminal cavity corresponds to the white/green wire. This wire goes right to the fuel pump. Using your jumper wire apply 12 volts to this wire for just a moment (you are bypassing the somewhat tricky control portion of this circuit). If the fuel pump is operational you'll get an immediate and powerful surge of fuel through the hose. If the pump does not operate, either the pump is faulty or you have a wiring fault between the relay and the pump.

8) If the pump operates with a jumper wire, plug the connector back onto the relay. The fuel pump circuit is so designed that it will operate whenever the starter motor is engaged so go ahead and engage the starter and see if you get fuel. If "yes", see Step 10. If "no", see the "Fuel Pump Circuit Diagnosis" checklist.

9) Remove the air duct from the front of the Air Flow Meter (AFM). With the key "on", move the air flap which is inside the housing of the AFM. This movement closes a switch inside the AFM and powers up the fuel pump circuit. You should get fuel in your container or a 34 PSI reading on your gauge. If not, see the "Fuel Pump Circuit Diagnosis" checklist.

10) If you have fuel pressure and good spark and still the motor won't start you should check the fuel injector circuit. The injectors receive voltage from the ballast pack (right fenderwell, across from the power steering pump). With the key "on" the two brown/slate wires goind into the ballast pack should have voltage. If they don't you have a wiring fault between the ballast pack and the "main relay" (on the firewall, white, black, brown, and brown/slate wires) or a faulty main relay. The realy can be tested this way: remove the connector. The terminal in the connector associated with the black wire should be ground. The white wire terminal should have "key on" voltage, the brown wire terminal constant battery voltage. If these are OK but there is no output to the brown/slate wire then the relay is faulty.

let me know after you verify each test.
Jose

 

The fuel pump came in the mail today. Installed it and I have a running car once again. I am considering putting a fuel filter before the pump too to protect it from possible tank dirt.

So you know what else is wrong with the car Jose. What should I tackle next? Power issue?

 

so it was the fuel pump after all? what happens now that you have a running car? what does it do?

 

I guess it was the fuel pump. Now if I start it cold, the first couple times it will start immediately and die. About the third time it idles smooth but as soon as I give it some gas it seem to suffocate for the first 30 seconds or so. Then it will rev up just fine. This is all on park or neutral. Once I drive, it still lacks power. Upto half throttle it is nice and smooth, but anything more and it suffocates again. Floor it and it just boggs down like making a sound like a loose baffle in a hollow tube is the best I can describe it. All just like it was before.

 

ok, the AFM can sound like that. It is the squarish box after the Air Filter cannister with the 3" accordion hoses on each side. This is part of the air intake system. Remove the large hose (bellows) after the Air filter canister, and look at the Flap inside the AFM, to see if it moves open and closed when accelerating the engine. You can accelerate the engine where the throttle cable connects to the intake butterfly.

Here's a picture of the engine components, so you can see the AFM.



[IMG]local://upfiles/1235/20910CE9AAE7450B9238E2CB923ADAF5.jpg[/IMG]

 

I checked the AFM (#4 as per the figure you sent). The valve opens nicely when I accelerate the engine. I also changed the plugs today. They were BLACK. Looks almost like it is running too rich. But even with the new plugs there was no difference. What next?

 

Do you have plumes of black smoke pouring from the tailpipes?