This is related to a 2008 HHR SS with factory turbo upgrade, otherwise a stock DD. Normally I just lurk here, but the knowledge base for LNF issue is much bigger here that it is on the HHR or Solstice/Sky boards.

A few days ago, the engine goes into reduced power mode. Codes are P0087 and P0089. If the car idles for a while, the CEL will go out, but will return and drop into reduced power with the slightest bit of throttle.

Scanner reveals a fuel pressure reading of about 70 PSI at idle. This should be something in the 1400 PSI range. I would think that the engine wouldn't even run with the rail at 70, but obviously it does, casting some doubt on the validity of the 70 PSI number. Interestingly, at key on, engine off, the rail pressure slowly climbs up to a few hundred PSI. Alldata says look at fuel pressure sensor, HP fuel pump, or injectors for these codes. There is no evidence of any injector related problems, which aren't too hard to spot on a 4 cylinder, and the goofy readings on the scan tool superficially seemed to point to a bad sensor. Normally, I don't like to throw parts at problems, but $30 for a sensor isn't a budget buster, so that's what I did. Beats the heck out of throwing a HPFP at it.

New sensor, same exact behavior, but with slightly different values at key on, engine off. I'm not counting on a sensor designed to read pressure in the thousands being terribly accurate at the extreme low end of the scale, so I'm content to accept that the problem is not sensor related. The only thing I can measure on the pump itself is the resistance of the regulator solenoid, and it showed about half an ohm, which is within the 0.3 to 0.6 ohm acceptable range.

This would seem to leave:

Mechanical issue with the HP pump itself
Wiring issue between the ECM and the pump regulator connector
Issue with the 12V or ground side driver transistors in the ECM itself
Software issue

There are no nasty noises coming from the pump, as is sometimes the case with HPFP failures, but definitely not a conclusive diagnosis. The pump has an internal pressure relief valve, which could possibly be stuck open. Hard to say, as the HPFP is not serviceable outside of unit replacement.

I plan to check continuity between the regulator solenoid connector and Pins 5 and 73 on the ECM connector. If that checks good, I can tap into the harness and put a scope between those pins, allowing me to measure voltage and see if the PWM pulses being sent to the solenoid are present.

My only knowledge of TSB's is derived from a 2011 version of Alldata, which shows nothing, but is probably far from up to date. Nonetheless, vigorous web searches have not come up with any TSB's related to software updates related to HPFP operation on LNF vehicles. Again, not conclusive, but I don't have access to GMSI.

Any comments from people who have gone a similar route, or have up to date TSB data would be greatly appreciated. I'd like to explore the options that don't include throwing a $400 fuel pump at the problem, before going down that road.

Thanks in advance.

 

Mike, you sound like you know your ****, so I don't mean to insult you with a stupid suggestion, but have you check the regulator wiring? These wires can sometimes get pulled and stressed.

 

Thanks. That's on my agenda for today. My regulator wires bend at the same sharp angle. Did you encounter a problem at that spot?

 

Pump is $250 new on Ebay or Amazon .I have a used one for $75

 

Thanks. If that turns out to be the case, I'll definitely give you a call about the used one. Rock Auto and Amazon are pretty close on a new unit, and both are about $100 cheaper than the discount online GM parts sources.

Anyone have a P/N for the fuel pump electrical connector in case that's the problem? With the TSB on the air duct fastener, I have to believe a few folks have had to replace them.

 

Someone else on here had that issue badly enough where the wire insulation got pulled back and allowed the two wires to arc. I read their post and went and looked at mine, which were fine, but WERE being pulled on, to I secured the wires to the A/C line near it.

 

Latest update:
Continuity is good between regulator connector and ECM connector. Flexing the wires at the fuel pump end produces no discontinuity. Have not had a chance to rig up a scope yet to look for the PWM signal from the ECM.

 

Sounds like you've passed the "wiggle-test," so on to the next thing. Hook up a physical fuel pressure gauge to the fuel pressure port and see what you get on it.

 

New fuel pump seems to have fixed the problem. I have about 250 PSI at warm idle and over 2200 PSI when I stand on it. The electrical part of the regulator solenoid in the pump tested good, and there was no leak from the piston side into the engine (another common failure), cam follower didn't show undue wear. I would suspect, at this point, that the spring that the regulator solenoid works against probably broke. It would be nice if I could get it apart and fix the spring. Doesn't hurt to have a spare lying around.

 

Glad you got it fixed and thanks for posting what you found. Might help someone else someday with diagnostics as you covered pretty much everything I could think of with the procedures you followed.

 

Where can I purchase the HPFP at?

 

ZZP has the best deal going for a new one, you can get it on ebay or direct from ZZP for a few bucks less.
Here's the link: Direct Injection High Pressure Fuel Pump - Fueling

 

Fuel pressure at idle should be 2-400psi 1400 till cat warm up is done. Ur pump could be bad, if everything else checks out. New pump.

 

Holy thread revival Batman!

 

Fail

 

how is that fail besides not reading 2 posts above and seeing its a super old thread? lol

 

Just because he already fixed it 4 years ago lol

 

Lol