Fp fluctuates, Engine runs lean at all RPMs

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V8hntr

Undersquare
Mar 7, 2007
85
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0
SoCal
2 weeks ago During driving I noticed the engine really hesitates at all RPM's and starts to lean and temperatures went up. My fuel pressure oscillates between 30-34 . When I remove the vacuum hose at idle the pressure doesnt change. I thought the problem could be my AFPR or Walbro pump or the wiring. So I first checked for codes and none were present. Next I jumpered +B and FP per TSRM to run the pump direct. As soon as I did the fuel pressure went to 55 psi and stayed constant. I then removed the jumper at which point the fuel pressure went back to fluctuating 30-35ish. I concluded that my Fuel Pump Relay or Circuit Opening Relay must be bad.

Do you guys agree with this? The dealer sells the fuel pump relay and circuit opening relay for $81 and $110 respectively. Should I get new ones or get used ones? I still havent narrowed down which of the two relays it is.
 
7MGTEsup

7MGTEsup

Formerly 'Down but not out'
Jun 14, 2005
614
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England
V8hntr;1132918 said:
I assumed they were bad already since the jumper solved the problem.
Click to expand...

You may have a faulty resistor pack, try unplugging the resistor and jumping it with a bit of wire.
 
V

V8hntr

Undersquare
Mar 7, 2007
85
0
0
SoCal
V8hntr;1133826 said:
I will test it this weekend and get back to you. Thanks guys.
Click to expand...

hello, I Tested the Main Opening Relay, Fuel pump relay and resistor, Main EFI relay per TSRM and they all are good in Relay operation and continuity.
 
grimreaper

grimreaper

New Member
Jul 2, 2008
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side note, if you dont plug the vacuum line to the afpr does the engine idle normally or is there any change?
 
V

V8hntr

Undersquare
Mar 7, 2007
85
0
0
SoCal
grimreaper;1136222 said:
side note, if you dont plug the vacuum line to the afpr does the engine idle normally or is there any change?
Click to expand...

It runs a bit rougher when I unplug it, but the pressures still fluctutes. What happens if it runs normally? Does that mean my AFPR is bad? I ordered the relays from a fellow SM member. Hopefully this will resolve it.
 
V

V8hntr

Undersquare
Mar 7, 2007
85
0
0
SoCal
Update:

I replaced the main opening relay and fuel pump relay. At idle the pressure now is steady and when I remove the vac hose fp goes up. However the car still runs lean at part throttle partial load. For instance in 3rd gear when I floor it as the rpm's increase the afr's goe 14.7, 15, 16,17, 18, until around 4000 rpm when the turbo is fully spooled. There is still a dip from 3-4k rpm and once the turbo fully spools the afr's are in the 11.xxx range. When I am cruising on the highway in 5th and start accelerating, the rpm/s dont rise above 3k or so. It seems like it drops into a dip and cannt get out. I dont know what do , may be get a different ECU or what could it be??? Help!!!
 
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