Where is the FPR located on a B-21 K-jet?? Any pointers on replacing it?

Do you mean Fuel Pump Relay, or Fuel Pressure Regulator?

A K-Jet does not use what we commonly refer to as a Fuel Pressure Regulator it does use a Control Pressure Regulator or some car lines refer to it as a Warm Up Regulator which is probably a better description of it's function. The CPR is located behind the distributor and under the intake manifold. It should have 2 fuel lines, 2 socket cap screws, and 1 electrical connection going to it. It's function is to regulate the control pressure to the top of the fuel head or the fuel distributor during warm up. For all intents and purposes it is the choke circuit of your K-Jet, it and the 5th injector. To check and see if it is good you need to hook up the fuel guages to it, fire it up so it runs and has good fuel pressure, shut it off and let it cool ALL the way down and then start it from a cold start and document the pressures and how long it takes them to rise and compare them to the specs in the book.

Pointers on replacing it? It is a straightforward, nuts and bolts kind of thing. Remove the dist cap so you have access and undo the fuel lines, do not loose the copper washers that seal the lines, undo the electrical to it, remove the two screws that hold it in and you are done. Some models will be vacuum referenced and if yours is then remove the vacuum lines and draw yourself a diagram first if the underhood one is gone.

Good luck
Mark

Informative reply mark but here's a picture of what I mean. Does my car use this? I do not believe it is an electrically controlled part, just a diapragm in there that I believe has failed. I don't know where it's located on the car but all the symptons (as per the FAQ list) point to its replacemnet

Yep, that is a fuel pressure regulator and if your car is in fact a K-Jet and not the later LH Jetronic then you do not have said part. If you do have an LH car it will be located on the front edge of the intake manifold and it will be attached to both the fuel rail and the fuel return line. All it is is a rubber diaphragm with a calibrated spring behind it that creates a controlled leak back to the tank to maintain fuel pressure. It also responds to vacuum so that when the vacuum source goes away, like when the throttle plate opens, it bumps the fuel pressure .5 BAR or about 7PSI. It does this not as an enrichment feature but just to maintain the pressure differential at the injector opening.

The end that is threaded and has a nipple on it, the threads are what is used to mount it with. A large 22mm nut threads down onto a bracket that you stick the threaded end through and this is what retains it. The nipple end of that same fitting is where the rubber fuel return line attaches via a hose clamp. The threaded fitting that comes out of the side is where the fuel rail bolts up to it, it is exposed to direct fuel pressure and it dumps the excess fuel through the other fitting that has the nipple and rubber return line on it. The little nipple on the opposite end is where the vacuum source from the intake manifold connects to it.

If you have one of these and you need to change it out make sure you undo the fuel rail fitting first while the whole thing is held stationary by the bracket and 22mm nut. Then undo the rubber return line, vacuum line and finally the big nut.

I hope that answers your questions, if not let me know.

Mark

Wow I feel so stupid. The FAQ's here list the failure of this part as a possible cause for my stumbling on acceleration and drastically low fuel economy. This is a problem I've been trying to fix for months now; whenever the engine is floored like in first second and third gears it stumbles and the tach goes wild. Sometimes it'll do this whene cruising along at 75mph but is accompanied by poor fuel economy. When I fill the gas tank it sometimes leaks from underneath it where the accumulator(?) is that meets with the return line. Plus the oil dipstick reeks of fuel! What a dumby I am. anyhow FCP sells the FUEL pressure regularor ( see the pic) as specific for B-21 but doesn't specify LH or K jet just auto or manual tranny. So like a dope I had one 2nd day air shipped for the the BIG BUCKs $$$ because I need to fix this problem for a long 1000 mile trip I'm planning this weekened and I'm realy wearisome of the 15mpg economy (at best) and the CONSISTENT stumbling on acceration what do I do now? I got some new Bosh Super spark plugs to put in and I'm replacing the thermostat, hoses, and coolant.
Thanks for your help Mark. Convert any bricks to that biodiesel stuff lateley? HAhHa :)

The stumbling and tachometer symptoms sound like they are ignition related. The fuel problem is something else, like a leaking cold start or main injector.
steve

The fuel accumulator next to the main fuel pump may have a return line that goes back to the tank separately from the return line from the engine -- as I understand it, that's supposed to return gas if there's a leak in the accumulator diaphragm. Anyway, there shouldn't be any external leak there, leaking fuel could really kill your mpg!

You might want to check the other fuel return line for kinks, a blocked return line could wreak havoc with the fuel pressure. Otherwise, you might want to find someone who can diagnose fuel pressure problems, which may not be so easy assuming this is a K-jet. I'd be pretty concerned if you're getting so much fuel going by the rings that you can smell it in the oil.

--
'81 GLT 245 @ 259K; '83 DL 175K

"Convert any bricks to that biodiesel stuff lateley? HAhHa :)" Smart A$$ :) Ha Ha Ha you very funny guy! Somehow I just don't get the whole Biodiesel thing. Jump through all of those flaming hoops so you can get LESS power out of your already miserably slow diesel and smell like a deepfat frier while you roll down the road! No sir, I just don't get it. Maybe I need to smoke a few more fat joints with Willie Nelson in his hemp-mobile, the Mercedes he set up to run on hemp oil. Now if he could only make it run on recycled bong water he'd really have something.

That sucks big time having overnighted an FPR that does not even go on your car. You need to start with the basics on your car, like fuel and control pressures checks, check for vacuum leaks (around the injectors especially), make sure that the O2 sensor is online and operational, check the Lambda relay, make sure that the frequency valve is buzzing, check the fuel mixture, check engine timing, make sure you do not have any vacuum lines loose or the intake bellows that goes between the throttle valve and the air flow sensor plate.

Let us know,
Mark

puff puff cough cough. Uh thanks Mark-dude. It has a brand new O-2 sensor but I will check out the other stuff too. Vacuum integrity is easy to check I suppose. Maybe i should quit smoking that stuff before I order new glow plugs, muffler bearings, and replacement Webers for my k-jet. Thanks again!

No problem, you will need a dwell meter and the appropriate allen wrench to check and adjust the fuel mix and to check you injector seals you just fire it up and spray around them with brake cleaner and see if it stumbles or if the idle increases. It sounds like it is running way too rich from your discription, but you never know.

Mark

Just to throw my hat in the ring - and it sounds like Mark's got things thoroughly in hand - I had rotten mileage & driveability, with plenty of backfiring and missing, when an ignition control unit went south on me. Actually blew the resonator apart trying to get to the shop... I think this is a relatively rare failure on Kjet though, more likely wiring related - particularly the hall switch leads from the distributor to the ICU.

As an aside, K-jet does have a fuel pressure regulator built in to the fuel distributor. It's adjustable, using shims, but if I recall correctly there's nothing but a ball, a couple of shims and a spring in there, and I've never heard of one failing.
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Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina

I have had that regulator apart before and it is just as you describe and I too have never seen someone have to adjust one. In theory it is just another controlled leak back to the tank only it utilizes shims to dial it in so I guess in a sense it is an adjustable FPR.

Blew your muffler off huh? I'll bet that got your attention. What kind of ignition was your K-Jet running the later Chrylser stuff or the earlier transistorized stuff that they went to after points?

Mark

It was the early transistorized one, I was about to leave on a weekend-long trip & since I had limited parts on hand I just put a breaker-point ignition in & ran it that way for a couple years. And yes, it did get my attention - thanks to the gaping rust hole under my seat I really got the full effect of it...
--
Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina