[DML] Fuel pressure question
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[DML] Fuel pressure question



Hello all,

I have had a hot start problem for a little while now. The car 
starts okay when cold, although sometimes it takes 4 or 5 seconds, 
or even cranking it a second time. If it's been sitting for anywhere 
from around 20 minutes to an hour and a half after running, I 
usually have to crank it a few times, wait a minute or two, and 
crank it about 5 more times for it to start. I got my hands on a 
pressure tester today, although I'm not sure if I used it correctly. 
The workshop manual said when using a pressure tester it would be 
necessary to jump the rpm relay and run the fuel pump without the 
motor running. The instructions for the tester said to do it with 
the engine running, so I connected the top port of the fuel 
distributor and the corresponding hole in the CPR, and did it with 
the engine running. If that's wrong someone let me know the right 
way please. Anyway, my results were primary pressure 4.8 bar (book 
says 4.9-5.5). Control pressure went from about 2.1 bar to 3.4 bar 
within about 15 seconds, and stayed at 3.4 bar thereafter. Checking 
rest pressure, upon shutting down the engine the pressure dropped 
immediately to 3 bar, then hit 2.7 bar after 30 seconds, 2.5 bar 
after 1 minute, 2.2 bar in 1 minute 40 seconds, and then once it hit 
2.2 bar it dropped drastically to 0 within 10 seconds. I believe the 
book said it should be a minimum of 1.7 bar after 10 minutes. 
However even with the gauge reading 0 bar it still starts 
immediately within about 10 minutes of having run (regardless of 
engine ambient temperature). Did I do the test incorrectly? And if 
not, does a primary pressure of 4.8 bar mean my fuel pump is not 
performing like it should? 

About the car: I've had the car for 2 years, the fuel pump is the 
same one that was in it when I bought the car, but is not the 
original. I recently replaced the filter on the fuel pump and the 
fuel filter. The fuel accumulator is the same one that was on the 
car when I bought it, I think the PO had said it had been recently 
replaced but I can't tell by looking at it if that is true or if it 
is still the original. I recently replaced the o-rings on the 
primary pressure valve plunger thing in the fuel distributor.

Where should I go from here? Any methods of better pinpointing where 
the rest pressure loss is coming from (I would guess between the 
accumulator or the check valve at the pump). Thanks for any and all 
help,

Dave
#5968








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