Car Died - Fuel Pump Module

jman1200

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I'll start by disclosing that my battery appears to be in its last legs, car starts fine but battery dies if I listen to the radio with the engine off or if I run anything else on acc.
I know these cars act funny when there are battery issues. I've been delaying this but plan to get a new one later today.

So last week I was cruising when the car died for a second, I released the gas and then pressed it again and it kept going. I thought it had been a transmission issue as it felt like it had slipped. About 30 seconds after that the "wrench" symbol came on the dash but no CEL or codes (on torque app). Got home, wrench cleared by itself when I re-started the vehicle.
Plugged in my laptop and ran Forscan for codes. Many came up but I don't know if they were related to the battery dying a few times over the past months. There were a couple related to the fuel pump.
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Cleared the codes, none came back up after I restarted the car a few times. Car ran fine since.

This morning on my way to work I felt the same cut-off felt last week, but this time there were for longer periods, it felt like if there was no fuel delivered. It happened about three times and then it died when I was going through an intersection. Was able to roll and get off the road. Tried to re-start it and it failed a couple of times (crank but no start). Got it going and it limped again a few times. Decided to go back home as I was only 5 min away.
Died again very close to home, this time it took multiple attempts to for it to start. It felt like it was trying but not getting enough fuel.
CEL came up while it was cranking, P00C6 - Fuel Rail Pressure Too Low - Engine Cranking.
"Oil" symbol came up on the screen as well.
Was able to get home, parked it, got in wife's SUV and came to work.

So I am going to change the battery and cross my fingers. Hope the issue is the PCM or fuel pump not liking what the battery is delivering.

I checked online for the fuel pump just in case it comes to it. I found that this vehicle has a right and a left fuel pump (???). I'd assume one is high pressure and the other one is there just because it was fun to have two... :confused:
https://www.tascaparts.com/auto-par...e/fuel-system-cat/fuel-system-components-scat
Items 12 and 13.

Two more things. Since I bought my SHO 2+years ago, the fuel pump makes a loud humm when it primes (every time I open a door). A few days ago I removed the back seat and cover to see what kind of pump I had; now thinking if me messing around there has caused a false contact on any of the connectors.

I've read this many times but please remind me what is the normal fuel pressure when using the OEM fuel pump. I want to monitor this even if car runs fine with a new battery.
 
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SM105K

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Jman, keep it simple. Change the battery and I am pretty sure most if all your issues will go away.
 

Zpak

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Sucks, but it seems after four years you’re on borrowed time with a battery in these cars.
 

jman1200

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I replaced the battery and the issue persists. Crank but no start. If it starts it dies within seconds. Same CEL code after clearing it several times.
Checked all connectors around the pump, cleaned them and didn't fix the issue.
I plan to remove the fuel pump and see if I can have it tested.

Any comments on the second fuel pump? What the heck does it do?
 

ridered74

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I replaced the battery and the issue persists. Crank but no start. If it starts it dies within seconds. Same CEL code after clearing it several times.
Checked all connectors around the pump, cleaned them and didn't fix the issue.
I plan to remove the fuel pump and see if I can have it tested.

Any comments on the second fuel pump? What the heck does it do?


On the 13 and up models the fuel pump control module is prone to going bad, not sure if the 10-12's have the same issue. It is a small black plastic piece, should be near passenger side close to door when you have the back seats removed. If you have a multimeter you could verify that there is voltage coming out of that going to your actual fuel pump.
 

jman1200

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On the 13 and up models the fuel pump control module is prone to going bad, not sure if the 10-12's have the same issue. It is a small black plastic piece, should be near passenger side close to door when you have the back seats removed. If you have a multimeter you could verify that there is voltage coming out of that going to your actual fuel pump.

This is good info, I'll google it. Thx.
 

jman1200

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Found this:

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Will check that tomorrow.
 

jman1200

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I've come to the conclusion that my car is possessed.

So, I disconnected the plug shown in the video (and below) in order to measure the voltage. Asked my daughter to start the car, got 12.X while cranking. This time car tried to start so it didn't crank for too long so we kept cranking it because I wanted to get a true reading... then the damn thing started... and kept running... with the plug disconnected... can someone please tell me what is that plug for??? If this is where you are supposed to measure the voltage delivered to the pump, how can the car run with it disconnected???

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Wait, it gets even weirder.

So I plugged the thing back and started the car several times. It started just fine every time. I even had time to data log the fuel rail pressure.

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So, blue dots is when I had it at steady 3000 rpm. Red dots are peaks when I rev it to get to the 3000 rpms. Lowest points of the graph is at idle. Comments?

I knew the issue wasn't going to fix itself, I needed to replicate the issue so I took it for a spin around the neighborhood. Sure enough, it died again when going up a small hill, it did not restart no matter how many times I tried or how many times I wiggled/reconnected that connector.

Pushed the vehicle back home, parked it in the garage. Gave it a shot and the damn thing started again... :madflame:

It restarted as many times as I tried and ran perfectly at steady 3-4k rpms.

Then thought, what if the issue has to do with inclination or movement. Rocked the car while it was idling, nothing, decided to put it up in ramps... within 20 seconds of being raised at the front, it started sputtering and died. It did not start again.
Went back to the plug and got nothing, 0 volts while cranking.

Because now there is no voltage the inclination theory is busted. At this point I think it could in fact be the fuel pump module that is failing when it warms up (all electronics produce some heat, right?).
Left it on the ramps and decided to let it cool down for the night. Will try again tomorrow to see if the voltage is back and in that case, I'll say the module is bad.

Meanwhile, can someone please explain why the car runs with that plug disconnected?
 

Johnbigdog

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The P0627 will set when the fuel pump module detects a problem internally or there is a circuit fault on the secondary circuits from the module to the pump, or internal to the pump. Basically the FPM is reporting to the PCM that it is detecting a fault within itself, the circuits to the electrical pump or the electric pump itself. It Could also be a fault with power or ground to the fuel pump control module, usually you get different DTCs. It very well could be the module that is at fault.

that image you uploaded, is that the driver or passenger side sender? Yellow grey is power, white brown is ground for the fuel pump of the 5 pin connector, only 4 pins are used.

It is possible that the H.P. Fuel pump was pulling fuel through the low pressure pump. it is a pump after all so it can pull fuel, but fuel pumps are better at pushing, then pulling usually
 

SM105K

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The P0627 will set when the fuel pump module detects a problem internally or there is a circuit fault on the secondary circuits from the module to the pump, or internal to the pump. Basically the FPM is reporting to the PCM that it is detecting a fault within itself, the circuits to the electrical pump or the electric pump itself. It Could also be a fault with power or ground to the fuel pump control module, usually you get different DTCs. It very well could be the module that is at fault.

that image you uploaded, is that the driver or passenger side sender? Yellow grey is power, white brown is ground for the fuel pump of the 5 pin connector, only 4 pins are used.

It is possible that the H.P. Fuel pump was pulling fuel through the low pressure pump. it is a pump after all so it can pull fuel, but fuel pumps are better at pushing, then pulling usually
John,

Could his in tank fuel pump be dying?
 

Johnbigdog

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John,

Could his in tank fuel pump be dying?

Sadly, yes. Maybe not a mechanical fault, but the F.P.D.M may be detecting an electrical fault. If Jman isn't getting power to the pump, I would be very closely inspecting circuits to the pump and probably throw the module at it before the pump.

One could provide fused power to the pump and see if the fuse opens, but I cant say what amp fuse to use to be safe.
 

SM105K

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Sadly, yes. Maybe not a mechanical fault, but the F.P.D.M may be detecting an electrical fault. If Jman isn't getting power to the pump, I would be very closely inspecting circuits to the pump and probably throw the module at it before the pump.

One could provide fused power to the pump and see if the fuse opens, but I cant say what amp fuse to use to be safe.

In other cars I have owned, the cars will start and run for a little bit and die. Wait a awhile and they start, then repeat the process...lol. All had weak or dying in tank pumps. I know this could be the case, but with the HPFP it could be just masking the problem.
 

Johnbigdog

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In other cars I have owned, the cars will start and run for a little bit and die. Wait a awhile and they start, then repeat the process...lol. All had weak or dying in tank pumps. I know this could be the case, but with the HPFP it could be just masking the problem.

Without a h.p. fuel pump I would agree but that h.p. pump may be able to handle no load fueling, untill the car is placed in drive and more volume is needed.

More PID data look at fuel rail pressure desired and compare to actual. That may prove that your just running off the h.p. pump
 

SM105K

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Without a h.p. fuel pump I would agree but that h.p. pump may be able to handle no load fueling, untill the car is placed in drive and more volume is needed.

More PID data look at fuel rail pressure desired and compare to actual. That may prove that your just running off the h.p. pump
That was what I was driving at. Nicely put.
 

jman1200

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The P0627 will set when the fuel pump module detects a problem internally or there is a circuit fault on the secondary circuits from the module to the pump, or internal to the pump.

Only codes so far since I replaced the battery and reset the codes have been P00C6 and P0087, both related to low fuel pressure. Po627 could have been there for a while, from the multiple times when my battery died.

that image you uploaded, is that the driver or passenger side sender?

That was the passenger side. That is the high pressure one, right?

I was hoping for you to chime in, I know you know how the brain of these vehicles work. That connector that I removed, is that power to the FP?

Is the video from YouTube accurate? No voltage = bad FPM? I got not voltage last night when it last died.
 

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