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XC90 V8 Intermittent fuel pressure cutout (kinked fuel pump line) Topic is solved

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo XC90s. The XC90 proved to be very popular, and very good for Volvo's sales numbers, since its introduction in model year 2003 (North America).
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abscate
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Re: XC90 V8 Intermittent fuel pressure cutout

Post by abscate » Sun Mar 04, 2018 9:04 pm

Nice meeting you shockwave.

Sorry I was overdressed but it was Sunday

What we need is for someone to find the full IEEE description of the ECM to PEM control signal, is it a TTL square signal or what ?

I thought it was a 0-5 V Square, when I’m back in ny I might be able

If your Volvo place has the ECM breakout box let’s try to get them to show us the signal
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Re: XC90 V8 Intermittent fuel pressure cutout

Post by abscate » Sun Mar 04, 2018 9:11 pm

Hmmm...from Swedespeed
When you replace the fuel pump, you have to be VERY careful to avoid kinking the plastic hose. If it is kinked, you will see some of the same symptoms. I had to replace a fuel pump, and had those symptoms. Dealer foreman said maybe kinked hose. I had done the work, so had to pay to have them do it again. The hose had a slight kink when it came out, BUT, they said that could be from taking it out. The dealer warrantied the pump, it was showing up to 86% duty cycle, and the engine would cut out. I sent them screen shots from VIDA, and the fuel pressure clearly would drop by 1/3. Seems to have happened more when turning a corner, but it happened often enough that they knew what to look for. Volvo never blinked on warranty claim, the dealer was very careful to document it, and they know me, and know I can do most of the mechanical work on my car. I just didn't know if I kinked the hose or not, but the kink wasn't enough to cause a problem, if I had done it. Sometimes, the hose is kinked so bad that it hardly flows fuel.

When you remove the pump, you have to try to swing the hose end so that it move almost at the very front edge of the tank, or else it hits a low spot in the tank, and gets kinked. Same for installing it. Use a wire connected to the driver side end when you pull it out, and then use the same wire (which was left in the tank) to pull the pump back in, but make sure the hose end is moving in a curved direction along the front of the tank. If you got straight across the center of the tank, guaranteed to kink the hose.
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CEM to PEM voltage

Post by SHOCKWAVE » Mon Mar 05, 2018 12:33 am

ECM --> PEM
Should be direct voltage? not variable PWM. That's the whole purpose of having a PEM...? However, the VIDA signal description:
#C20 to #B20 --> "Control signal (PWM) from electronic control module (ECM) to fuel pump control module (PEM). Fuel pump control module (PEM) controls the fuel pump in turn." I don't think that is stated correctly by Volvo, so what do we make of it?
If it's 0 - 5V, errr way out of range.
If it's 0 - 12V, we were seeing (7 +/-.5 )/12 = 58-63% output to PEM. Not a good pump duty cycle for idle.
If it's 0 - 18V my latest readings at 8.05 - 8.13 (/12) give 45% signal which is the correct value for pump duty cycle...
That is all assuming the control signal TO the PEM is directly proportional to the duty cycle FROM the PEM.

PEM --> Pump
PWM (white and white/black) which controls the pump speed. That is not monitored in any way by the computer(s), I believe...only the result at the FPS. If the ECM doesn't get what it wants at the FPS, it increases the direct voltage to the PEM (which in turns increases the frequency of the PWM signal to make the pump turn faster). I don't have any info on what that signal looks like or should be as you have also stated and are requesting...I can try the multimeter on this just to see what I get... It probably can't react fast enough, but maybe I can get the frequency...

CEM --> PEM
Delivers 14.0 V (full voltage to PEM for power).


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Re: XC90 V8 Intermittent fuel pressure cutout

Post by abscate » Mon Mar 05, 2018 3:16 am

Even more confusion here

This is from my 2005. It refers to ECM to fuel pump control module !( another name for PEM) control by serial communication, then FPCM varying fuel pump voltage by PWM signal on the ground lead of fuel pump.

Still no data on what these signal should look like.

Text follows:


Fuel pump control module (only vehicles with demand controlled fuel pumps)



The fuel pump control module powers the fuel pump and regulates the output of the pump. The fuel pressure changes with the output of the pump.
The fuel pump control module is supplied with battery voltage by the fuel pump (FP) relay and is grounded in the car body. The fuel pump (FP) relay is controlled by the central electronic module (CEM) when requested by the engine control module (ECM).
The engine cannot be started if the power supply to the fuel pump control module is faulty because the fuel pump will not then be powered.
The fuel pump control module is controlled by the engine control module (ECM) via serial communication. The fuel pump control module then controls the fuel pump by transmitting pulse width modulated (PWM) signals on the ground lead for the fuel pump. This means that the voltage drop across the fuel pump changes, and with it the output of the fuel pump. See also: Function See: Description and Operation\Engine Management System\Function
The central electronic module (CEM) controls the fuel pump (FP) on models without on-demand fuel pumps.
There are no diagnostics for the fuel pump control module. The engine control module (ECM) has diagnostics for fuel pressure regulation and the associated components.
The pulse-width modulated (PWM) signal from the engine control module (ECM) to the fuel pump control module can be read using VIDA.
The fuel pump control module is on the outside of the fuel tank.


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Re: XC90 V8 Intermittent fuel pressure cutout

Post by abscate » Mon Mar 05, 2018 3:29 am

Shock...another kinked hose here in this thread

This guy might have the data we seek

viewtopic.php?t=80351
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Re: XC90 V8 Intermittent fuel pressure cutout

Post by abscate » Sat Mar 10, 2018 5:23 am

Shockwave...found this crawling the web, unverified

Link

https://www.picoauto.com/support/topic14491.html

Waveforms if ECU and PEM to drive pump
IMG_0017.PNG
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Re: XC90 V8 Intermittent fuel pressure cutout

Post by matthew1 » Tue Mar 13, 2018 9:37 am

Shockwave, check out the comment from Brett Borders here https://www.matthewsvolvosite.com/2007- ... ent-154382
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Re: XC90 V8 Intermittent fuel pressure cutout

Post by matthew1 » Tue Mar 13, 2018 10:42 am

Also, I made your account MVS Contributor level, FWIW. Your documentation in this topic has enriched the forum.
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Re: XC90 V8 Intermittent fuel pressure cutout

Post by SHOCKWAVE » Tue Mar 13, 2018 12:00 pm

Thanks Matt! Also, Brett. I was going to open it up this weekend, but I got a 7 stitch cut on my finger early Saturday doing woodwork. I plan on getting in there by this weekend at the latest (cancel Volvo service appt on the 19th). Hopefully there's an obvious rat in there! :twisted:


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Fuel Pump Inspection

Post by SHOCKWAVE » Fri Mar 16, 2018 11:21 am

Ok, so finally got to it this morning (4:30-6am). No rats in the tank. Everything looks fine except for one thing. The return hose (4) from the left side tank looked to be out of position (not in it's channel). I inspected this before getting the pump all the way out so as not to have the pump removal disturb any root causes. Once I had the pump out (not fully as it seems to be enough to inspect without pulling the hose all the way out from the other side), I took MANY pictures, but I couldn't see any other obvious issues. Very small metal particles in the bottom of the tank, but only maybe 5-10 that I could see (left side).

Now, do I pull the hoses off the assembly and check them for obstructions? or could it be that the "return" hose (4) being out of position is not filling the reservoir? I imagine it sprays and the reaction force pushes it farther out of position so it overshoots. Then the reservoir does not get filled up. I fitted it back in it's channel on the outside of the reservoir, but it comes out easily if I gently fiddle with it. Maybe it needs to go all the way down so the elbow is just over the top. I didn't have time to see if the elbow was too wide for the channel/retainer, but it seemed like it was only wide enough for the hose and no the bottom of the elbow...I'll have to tie a wire around it to keep it in place I guess...Anyone know the nominal position of item (4)?

NOTES:
1. What is item (2)? It has an open end in the reservoir and an outlet on top. Where does that outlet go?
2. Gas gauge was at 1/4 tank before starting. I siphoned out the left tank and got about 4 gallons. That seems too much on that side. I did not siphon the right side, but it looked as full as the left.
3. What is item (5)? Seems to be a check valve...
4. I'm still not clear on the fuel transfer operation (viewtopic.php?t=60022). How does the pump reservoir stay full once the left side is emptied? Does item (2) perform that function via a siphon type operation? I'd guess that item (2) terminates at the bottom of the RH tank. But that means there are essentially 3 pumps...
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