Re: [DML] Re: impossibly high fuel pressure?

[Soma576@xxxx]

Hello David (and the rest of the list), 

you have so many things to say, i'll just answer each part individually or 
else we'll both get very confused!!

n a message dated 4/10/01 9:21:40 PM Central Daylight Time, 
jtrealty@xxxx writes:

<< > Before you give up I have some ideas you can try. If indeed your 
> primary pressure is too high besides the primary pressure regulater 
> being stuck (which you say isn't) >>

i have pulled the bolt and spring/pin assembly. the whole thing is very 
clean with no corrosion or debris. the pin in the spring moves easily, and 
the hole in the bolt is not plugged from either direction. so i must assume 
that this piece functions correctly. after all, there's hardly anything to 
fail, except for the diaphragm inside the fuel distributer.


<<another possability is a restriction 
> in the return line from the regulater to the tank.>>

from the fuel distributer to the tank, everything is kosher. remember? we 
put a bucket around the return line in the tank and we measured out the 
correct amount in one minute (2 liters) as stated in the shop manual. i also 
removed the return line from the control pressure regulator which goes into 
the side of the fuel distributer. i ran the fuel pump and fuel flowed out 
very freely, without sputter or dripping. this says that the control 
pressure regulator is not plugged on the return end, correct? i would assume 
so.

<< Since your resting 
> pressure is about right the fuel accumulater is probably OK.>>

i would be inclined to agree. 


<<A quick 
> and dirty test is to remove the return line from the regulater and rig 
> up something temporary into a pail and see if the pressure is now in a 
> more normal range. >>

can you describe this in greater detail? i don't know if you are talking 
about the return on the control pressure or the primary pressure. and when i 
remove it, from what end of the hose? if you could get more specific, i 
might be able to see what you mean, and maybe i've already done that.

<<I think the noises from the pump are just it trying 
> too hard against the high pressure, after you can get the pressure 
> right the pump might be alright. >>

that would make sense if the INTAKE side of the fuel system were plugged. 
however the fuel pump is capable of putting out over 120 PSI of fuel pressure 
(typically they are twice as strong as the system requires), so i do not 
think the pump is strained. i was reading about 7.5 bar of pressure which 
is around this PSI level. i believe the pump is as strong as it should be, 
but it might not be CONSISTENT!!

<<If you cannot regulate the primary 
> pressure don't bother checking the control pressure, it will be too 
> high also, it also dumps into the return line to the tank and besides 
> it receives "regulated" presssure from the primary regulater so if 
> that is too high the control pressure reg can't reduce it enough. >>

this is what i believed about two days ago. however i have since talked to an 
engineer at bosch and a K-Jetronic guru at a local import dealer here, and 
they both say that it is possible to read pressures in excess of 6 or 7 bar 
due solely to a failed control pressure regulator. the primary pressure 
regulator may be working just fine, however it is possible to get too high of 
pressure AFTER the primary pressure. i don't really understand it, but both 
of these guys insisted that the control pressure regulator is at fault. the 
guy at the import dealer noted that i said my system pressure was measured at 
about 6.5 bar today and my control pressure is at 3.5 bar on a COLD ENGINE!!! 
this is definitely not right he said, and the problem lies within the warm-up 
regulator (CPR to us DMC guys). the problem is the difference between the 
system and control pressures is too narrow. the warm up pressure on a cold 
engine is spec'd at around 1.5 bar (i don't see that spec in the shop manual, 
but he insisted that all of these systems are the same, even on the 
DeLorean), while the hot running temp pressure is supposed to be around 5.1 
bar. you see the vast difference between the cold and warm pressures? he 
insists that this is the problem. he says that if i replace my control 
pressure regulator, my overall system pressure will stabilize and things 
should be close to perfect again. however, after all of this pressure shock 
to my fuel system, i may need to add or remove a couple shims on my primary 
pressure. this weekend i'm borrowing a fuel pump and CPR from a couple kind 
DML'ers and i have a feeling i will have a few more questions answered this 
weekend... and i'll be sure to post to the list what happens. 

if you or anyone else have any ideas, let me know.

Andy

Soma576@xxxx
1982 DeLorean DMC-12 VIN#11596
Fargo, ND 58102


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