928 at last

That's the next thing then. I'll reverse polarity for a bit with everything in place and see if that makes a difference. If not, I'll have to start pulling things apart.

Will report back tomorrow after work!.......the saga continues....

FredR

Rob,
There are two tests that characterise whether a pump of this type is working correctly. One is a shut-in head test where you ensure nothing can flow [injectors disconnected, FPR discharge blocked] and measure the head the pump generates- for the fuel pump the number you are looking for is 3.8 barg. The other test is the one I referred yesterday which is an “end of curve” test wherein the pump produces no head and you measure how much flow it generates in a given time interval. If there is a problem with this test then either you have a blockage or a pump problem of some type. Do not rule out a blockage in the fuel filter however ulikely.
As others have stated, if the in tank hose has gone there is the chance that debris has entered and blocked the main pump. If the main pump was jammed I doubt you would hear it whirring away. My experience with in-tank pump hose failure is that all you notice is loss of top end power-nothing more [assuming no blockages].

I do not know much head the in tank pump generates but it is conceivable that may explain the 10 psig you are seeing but I would expect it to reach this quite quickly however presumably your injectors are opening as well so that may mask what is going on as fuel squirts into the manifold albeit in much lower doses.
At this moment in time in your position I would preferentially remove the main pump and test it off the car for fuel delivery [you can do it in situ by using some hose and a jubilee clip on the end of the fuel rail- it should not generate any pressure as you pump the fuel into a container].
You can also reverse the polarity and thus reverse flush the pump to see if it spits out any chunks of rubber but not in situ whilst connected to the suction as any debris could possibly be pushed back into the in tank pump even if the hose is breached.
If you use petrol as the pumped medium be careful and have water hoses on standby. You could also use water but I would flush it out immediately after the test with either petrol or diesel to avoid any chance of corrosion setting in.

Regards

Koenig-Specials 928

Sure thing Rob. I'll come for a drive one summer's day or if you're gonna be in the TO area let me know. Sometimes I go for a quick spin the the Halton Hills area just for fun.

Koenig-Specials 928

Rob after you flush the pumps manually verify that fuel actually gets to the front of the car as was suggested earlier. Carefully remove the cap from the front of the passenger's side fuel rail (depressurize line, rags in hand etc), attach a short hose and have someone run the pump for 1 minute and see if you get about 1.5 litres of fuel. That will say whether or not you're enough getting fuel to the front.

yardpro

i am betting that you have a pump problem or a fpr problem..

if a pump has restricted flow it will still build it's maximum static pressure (with no flow)...
if the injectors are closed and you jump the pump, you should get the 55psi even if the flow is restricted.
remember there are two aspects of any pump, pressure and flow, they are analogous to volts and amps...

Koenig-Specials 928

Above test with the plug removed will validate flow to the fuel rails

James Bailey

If you remove the fuel rail cap # 20 above be SURE that you catch #19 the ball bearing. Because it will jump down out of sight, never to be seen again, faster than you can say, Oh ****...

Calgary Ole

Thankyou James...When I repaired my AC last spring I found a ball bearing sitting on the compressor and have it taped to my tool box in hope that I would know where it belonged one day. I had removed the fuel rail cap the year before to install a fuel pressure guage. I can now put it in a baggie with the cap.

928 at last

The #19 "Oh ****" factor has already been eliminated with a pressure gauge.

928 at last

And like Ole's now, is safely ziplocked in the parts box....

928 at last

Quick Question,
Any danger of a feedback issue if I reverse polarity on the pumps in place with the relay, fuse and jumper removed?

928 at last

FPR Theory of Operation needed.
Weird (Yes Again). I didn't check the pressure gauge last night after I checked the FPR and dampers for vacuum. (All held 20 inches per my previous post....). I haven't energised the fuel pumps since about 7 last night in fact, at which time, after some running the gauge was showing approx. 8 lbs on the rail. Well, I go out tonight , like five minutes ago, and the rail is showing 56 lbs of pressure.
Just one comment, WTF?
The only thing I can possibly think of is that there was "backpressure" in the system that I somehow released while testing the vacuum.
While this would seem to be good news on the integrity of my fuel system, (holding pressure for some 21 hours), it certainly begs the question of what the hell is going on with the regulator and if what has apparently happened is even possible.
Leave it up to me to come up with something like this.......

Imo000

Hmmm..interesting. Either way, if it happened once, it will happen again. Something is fishey with the FPR.

928 at last

I just replicated the vacuum test, after replacing the relays and fuse, with a start attempt, and the rail pressure dropped to zero again. No recovery in pressure after the vacuum applied. I was watching the gauge this time. (Am I having fun yet?).

I'm just going out now to reverse the polarity on the pumps and see what that does.

928 at last

Further Update....
I'm going to page Alan in another thread.....I'm now deeply into WTF territory, and becoming less comfortable.....
Pulled the relays for the ignition, EZK and LH, Jumpered the fuel pumps and could hear everything working as before.
Then, pulled the jumper and the fuse for the pump, and while rigging a groundline off of the battery directly, (for the reverse polarity to the pumps) the loose end happened to touch my exhaust tips.
Major blue arc action.
Checked with the digitial volt meter and I have a better reading from battery ground to the exhaust than to the positive terminal on the battery itself.
Anyone have any idea exactly which level of Dante's Inferno we're at here????