Fueling issues 2012 MS3

MS3Silver

MS3Silver

Greenie N00B Member
Greenie Member
Looked around a bit and can't find anything quite like what I am experiencing at the moment. A little while back my car was warming up, sputtered, and died. Couldn't get it to start afterwards. Engine would crank, start, and immediately die like it was starved of fuel or something.
After some diagnostics, at the recommendation of someone in a MS3 discord I'm a part of, I replaced my Fuel Pressure Sensor and the car now starts and will idle. The issue I'm running into now is my fuel pressure. During idle and once it's warmed up, it sits from 450-500. However during warmup, it never rises above 1050~ and as it tries to, a whistle-like noise can be heard. I pulled my relief valve and couldn't blow any air through it but ordered a new one just in case. Got the new one installed and I'm still having the same symptoms/issues. Is it common to order new ones that have already failed?
All fuses have been tested and aren't the issue. I haven't yet tested the resistor and I plan to do that soon, but from my understanding it seems like the pump is getting enough power to get the pressure to where it needs to be, it's just not holding it anywhere past 1050~.

I'm at a loss at this point. Thanks for any input or suggestions you guys might have.
 
Post a cold start log.

Edit:
The ITFP only needs to supply a small amount of pressure to keep the HPFP fed so it's unlikely that it's an ITFP issue, unless the filter is clogged. I say fed because the HPFP can't produce suction, only pressure and has to be fed to work properly, as do all positive displacement pumps. If you aren't making pressure, there's either a mechanical failure in the HPFP or the rail valve, or you need to do some cleaning.
 
Last edited:
@Enki Here's the cold start log. This time was odd though. Typically it struggles to get above 1000psi for fuel pressure and it was just short of it this time. I may have to pull the pump next week and do a tear down and cleaning. Before even starting the car though, I noticed the fuel pressure was sitting around 30-36. Shouldn't it be higher(around 50-60?)
 

Attachments

Pressure looks fine for idle if not a hair low.

HPFP pressure is based on load and RPM, and it looks to be in line with what I have, which may not be 1:1 for your tune, but gets the point across.

upload_2020-1-5_12-37-51.png
 
At idle, it seems fine. It's once I start getting on the throttle it can't push past 1000 and I get the squeaky/whistle noise from the fuel pump area
 
If you've already replaced the PRV with known good, I'd next rebuild the spill valve and clean the HPFP internals. remember to check the spill needle with a thumbnail for sticking.
 
Checked the spill valve and everything checks out. Not sticky at all, and I don’t know that I’m surprised as I don’t have any corn available within 2 hours of where I live.

Did a KOEO test and the pressure only built to around 950~, about the same during any start up or even driving. It’s not failing so to say but it’s not building to where it should be.
 
Don't fall into the fallacy of complacence.
I bought a used pump for experimentation from a blown CX7 many years back; it was seized from black death so bad it came with the housing that bolts to the head (the part the HPFP bolts to). It took a hammer and prybar to get everything apart, with soaking in all kinds of shit overnight.

The car never saw a lick of corn, just shitty oil (which is the root cause of pump issues, if you weren't aware; corn only accelerates it).
 
79k

I plan to check the fuel filter this weekend and disassemble the fuel pump to check for any failing seals
 
Update: took a little longer to get into my ITFP than I would have liked. Replaced the filter, nothing’s changed. Still getting readings of 33psi while at the ON position and also while jumpering the relay. Wondering if it’s now my pump that’s my issue.
Took a multimeter to the power wire to the itfp, read 11, as well every other power connector in my bay.

Took apart the hpfp, all seals replaced. Oem ones were fine. No damage to internals or piston.


Sent from my iPhone using Tapatalk
 
The tank pump should be closer to 60psi. You could do the drop in aem pump. It's not crazy expensive and worth a shot. A
50-1200 E85 In-Tank Fuel Pump
Template public:_media_site_embed_amazon not found. Try rebuilding or reinstalling the s9e/MediaSites add-on.

Pretty sure that's the one.
 
JohnnyTightlips said:
The tank pump should be closer to 60psi. You could do the drop in aem pump. It's not crazy expensive and worth a shot. A
50-1200 E85 In-Tank Fuel Pump
Template public:_media_site_embed_amazon not found. Try rebuilding or reinstalling the s9e/MediaSites add-on.

Pretty sure that's the one.
Click to expand...

That’s what I was thinking. Thanks for the link, I’ll save that for now. I need to tee a gauge to the tank and get a more accurate reading before pulling that trigger.
I switched back to my original pressure sensor and now it’s reading 2000~ psi and I have a p0091 and p0193 now. Now I’m considering that I have a problem in the wiring harness somewhere.


Sent from my iPhone using Tapatalk
 
MS3Silver said:
That’s what I was thinking. Thanks for the link, I’ll save that for now. I need to tee a gauge to the tank and get a more accurate reading before pulling that trigger.
I switched back to my original pressure sensor and now it’s reading 2000~ psi and I have a p0091 and p0193 now. Now I’m considering that I have a problem in the wiring harness somewhere.


Sent from my iPhone using Tapatalk
Click to expand...
I had the fuel pressure sensor plug come loose and the car ran like garbage and it defaulted to max reading if I recall.
 
MS3Silver said:
That’s what I was thinking. Thanks for the link, I’ll save that for now. I need to tee a gauge to the tank and get a more accurate reading before pulling that trigger.
I switched back to my original pressure sensor and now it’s reading 2000~ psi and I have a p0091 and p0193 now. Now I’m considering that I have a problem in the wiring harness somewhere.


Sent from my iPhone using Tapatalk
Click to expand...
Look whose here haha!

Yeah, if there is an open circuit then it will read the maximum sensor value.
 
JohnnyTightlips said:
I had the fuel pressure sensor plug come loose and the car ran like garbage and it defaulted to max reading if I recall.
Click to expand...

What was your fix? Replace the sensor or rail? That seems to be exactly what I’m seeing. I’ve also read that a faulty spill valve can cause stuff like this, which corresponds with my other DTC.


Sent from my iPhone using Tapatalk
 
Spill valve controls rail pressure, not ITFP pressure (which is controlled by the regulator that's held in place by the filter).
 
Enki said:
Spill valve controls rail pressure, not ITFP pressure (which is controlled by the regulator that's held in place by the filter).
Click to expand...

Right. I just don’t think my itfp is my issue at this point. I believe it’s related to a wiring harness or my spill valve. Gonna see if a buddy of mine will let me swap his in and see if there’s any difference.
 
You misunderstand. If the rail only sees 33 psi, the ITFP is only supplying that much.

It's a closed hydraulic system, with a check valve for the rail; the spill valve *cannot* influence rail pressure to be below ITFP pressure; it's just not possible due to the design (at least, not with your symptoms anyways).

If the spill valve did fail in the worst mode possible (closed), this could influence rail pressure, but you'd also see your rail pressure exceed rail sensor max at idle. Even then, the only thing holding it closed is either internals pumping pressure (not a factor KOEO) or a tiny spring that I would imagine has a ~2 psi crack pressure max.

If it failed open, well, fuel has a straight path to the rail and it's not a factor anyways.
 
Enki said:
You misunderstand. If the rail only sees 33 psi, the ITFP is only supplying that much.

It's a closed hydraulic system, with a check valve for the rail; the spill valve *cannot* influence rail pressure to be below ITFP pressure; it's just not possible due to the design (at least, not with your symptoms anyways).

If the spill valve did fail in the worst mode possible (closed), this could influence rail pressure, but you'd also see your rail pressure exceed rail sensor max at idle. Even then, the only thing holding it closed is either internals pumping pressure (not a factor KOEO) or a tiny spring that I would imagine has a ~2 psi crack pressure max.

If it failed open, well, fuel has a straight path to the rail and it's not a factor anyways.
Click to expand...

Ok that makes sense. So with the new sensor, I see 33psi with the key in the ON position and normal idle pressures, but nothing over 1000~psi.
The old one always shows close to the max value, ON or idle. I guess this wouldn’t point to a spill valve then since I’m getting different readings with different sensors right? It would most likely be electrical?
 
You must log in or register to reply here.
Back
Top