Sometime last year, I posted that upon purchasing my 1985 XJ6, I removed and flushed out my fuel tanks, added two filters before the pump, installed a new fuel pump. I also cleaned every single electrical connector I could find and the end result was a fine purring kitten. I have only driven this car for about 5 miles within my subdivision, because it is not yet registered to legally drive.
Recently, I posted about the removal of the intake manifold to replace the freeze plugs on the block. I completed that and replaced all of the small vacuum hoses, serviced my ignition system and reported that my car required prolonged cranking time to start. I said then that I believed that my fuel pressure was bleeding down. Forum members contributed with all the known ways to build the pressure up to start the engine, to no avail.
Having said all of the above, I decided to really work on the car to get it right.
I purchased an inline check valve, new fuel hoses and dedicated most of the morning to working on the fuel system.
Bear in mind that after cranking for about a minute the car would start. Yesterday however, after installing the inline check valve, replacing all of the fuel hoses, attaching the gauge to the cold start injector hose, my fuel pressure was only at 10 psi.
Figuring that I did something wrong, I removed the check valve, reconnected the hoses and the fuel pressure stayed at 10 psi.
I then attached the gauge at the outlet of the fuel pump and the reading is 10 psi.
This $196.00 pump gave me 5 miles of driving and a couple of hours running in my driveway.
Today, I am going to pull the pre-pump filters and the pump to see if I still have some crud, even though i had flushed the tanks prior to the installation of all new fuel system components.
In the event, that I need a new pump, which pump do you all recommend?
I will post the brand of pump I installed when I get to the car.
Also, I performed the following test on my FPR.
Even with my 10 psi I disconnected the outlet of the FPR, and with no vacuum fuel flows out of the outlet side.
I applied 15 inches of vacuum and the result is the same, fuel flowing out the outlet side of the FPR.
I am assuming that no vacuum equals WOT so there should be very little fuel returning to the tank and with vacuum applied equaling idle speed there should be more fuel returning to the tank.
Is my FPR faulty? I will determine today if I need a fuel pump and can someone tell me how the FPR works? I need to determine if the FPR is faulty as well.
Thank you for reading my rant, but its driving me nuts.

 

Up to this point I would've say that the pump might be OK but it sounds as though the FPR is faulty....




But clearly something is amiss as you should get 75 psi or more



The OE Jaguar/Bosch pumps were high grade...and no doubt high price. I'd call up David Boger and get a good used one. As for new pumps, I'm not sure what brand to recommend. Others will chime in.




It does seem like the regulator is faulty as there is no apparent difference in return flow with or without vacuum applied. However, the amount of return flow you're seeing might already be the minimal amount. If the fuel pump was up to snuff you might see a marked difference in return flow using your vacuum/no vacuum comparison.

It is obvious, however, that 10 psi from the pump outlet is wrong. Either the pump is faulty or there is a supply problem *to* the pump.

I'd fix the known problem ^^^^ first ..... and then revisit the FPR test.

Cheers
DD

 

I'm still running an original 30 year old pump from a Series 3. Mine is a OE Bosch and says "Made in France". This is the case because I also didn't have any luck with a newer style pump. My tanks did wreak the first OE pump I had but since then I've replaced one tank with new and added prefilters. Sofar so good! As you mentioned, cut open the prefilters and inspect them... if they are the clear type then that's not necessary.

FPR and the fuel system in general is easy to test...

TRY THIS...With the pump running, pinch off the return line, pressure should immediately rise to as much as 100 PSI. Not necessary to get the pressure that high because you could blow off a hose. So pinch it off slightly, as you do the pressure rise should be immediate. If the pressure rises slowly to 100 or so, you have a clogged filter or some other blockage. IF the pressure doesn't rise at all you may have a bad pump.

The test you performed as described isn't very useful in diagnosing the issue because vacuum has minimal change on the fuel pressure...only about 3spi and only when full pressure is reached. So appoximately 40 PSI with no vacuum and 37 PSI with vacuum

The FPR is a spring a diaphragm...as the pressure rises against the spring a valve opens and lets fuel return to the tank. Equilibrium between spring pressure and fuel pressure in relation to the valve occurs at about 40psi.

 

How can 100 psi possibly be achieved if the deadhead pressure taken directly off the pump is only 10 psi, as mentioned in the posting?

If the *regulated* pressure is supposed to be in the 35-40 psi range, you need a pump that is capable of producing *more* than 35-40 psi !

Cheers
DD

 

Its a good question and we dont know if the OP used the T fitting commonly provided with most Fuel pressure testers or plumbed it direct.

 

From this......

......I assumed it was plumbed direct.

Worth clarifying

Cheers
DD

 

Yesterday I removed the previously installed pre-pump filters, change over valve and the fuel pump from the car. Fuel filters are clean as a whistle, change over valve operating as it should. Tested the Bosch fuel pump separately and it failed. 12 psi. David has a used pump advertised on his website, so I will try to contact him or purchase it online.
Another issue (if it is) is that I am only seeing 9-10 volts at the pump wiring in the trunk.
I tested the pump with the existing voltage at the pump wiring in the trunk and with 12 volts directly from the battery with the same results.
If I am not able to get the OEM pump from David, I saw a pump on Amazon HFP 603 which is a replacement for CAC4269 and a FPR #0280160214, both for about $150.00. What do you all think. My failed Bosch pump costed more that that