Gen 3 coyote fuel pump not getting power

[elismithc]

This seems to be a common roadblock and I believe i've done my due diligence in trying to diagnose the issue, but no other person I've found has had a solution that has worked so far.

For reference, mark 4 roadster with gen 3 coyote running the ford control pack

My issue is the dark green fuel pump wire from the ford harness is not receiving 12 volts (not even the momentary 12v when the system is just priming). I have seen 8.9 volts once but this is out of dozens of different attempts to get results. I have directly powered the external pumps to know that they work. The light green ignition relay trigger from the 16 pin connector is seeing 12V when the key is turned one click, and the throttle body is responding. I have tried both a chassis ground and grounding on the battery for the fppdb. All fuses and the fuel pump relay are seeing an input of 12V in the fppdb. This shouldn't have anything to do with the RF chassis as I am simply checking for voltage at the end of the dark green wire, sometimes rigging up the fuel pump to the dark green fuel pump wire directly (circumventing the RF setup) to see if I'm getting a bad reading on the VOM.

The starter is also responding, although it does sound like its getting inconsistent signal or sometimes only making one "turn" of the motor before stopping, but I also bench tested it and it spun without issue. The transmissions is also disconnected from the bellhousing currently because it was causing binding somewhere within the twin disk clutch setup, so that is no longer part of the equation. This should have nothing to do with the fuel pump wire, but TLDR, starter is receiving power.

I have contacted ford performance's tech line about this as well, but given that they still haven't responded to my last email from a few months ago, I figure i'd try here.

[jiriza84641]

double check you are getting 12 volts to the Ford PDB. and that the PDB is HAAT. the 250 A fuse has 12v also.

how do you have it wired up?

look at EDWARDB roadster build for reference.

[edwardb]

Wiring the Coyote system is relatively simple and with just a few elements its should work.

- +12V battery power to the PDB through the supplied 250amp fuse. Obviously nothing is going to work if this isn't present and robustly wired. I'd also confirm the health of your battery. Maybe try another one if you have one.

- Coyote harness properly grounded. Ford recommends taking the ground directly to the battery, which I have done on my installations. Although a solid chassis ground (metal-to-metal assuming the battery ground is also solid) should work.

- Light Green Ignition Relay Trigger wire from the Coyote 16-pin connector to an ignition controlled +12V source in the RF harness. I've used the orange EFI-COIL wire (probably the most common) and also the tan ELECTRIC CHOKE wire. Easy enough to confirm either of these sources are a solid +12V when the key is on. The Ford instructions are very emphatic that if this source isn't solid the starting and running of the Coyote will be affected.

- Light Blue Starter Motor Request (SMR) wire from the Coyote 16-pin connector to an ignition key START controlled +12V source in the RF harness. The light blue EFI CRANK POWER wire is normally used. Again, easy enough to confirm this wire is getting +12V when the key is moved to the start position. Note the other light blue IGN SW->NS SW wire normally routed through a clutch safety switch at to the the starter solenoid is not used. If can either be removed or capped. I remove it.

- Accelerator pedal (DBW) installed and cable plugged in.

Assuming each of these are wired and tested exactly as listed, and you don't have any blown fuses in the PDB, the Coyote has what it needs to start and run. Yes, you should see a brief +12V at the green fuel pump relay out wire when the key is turned on. It's quick though and in my experience not the easiest to read. But it's there. Note also that the system takes about 10 seconds to reset each time power is first applied. So you won't see this brief +12V again until after it resets. You can hear the relay in the PDB clicking after the 10 seconds or so. Yes, you should see +12V on the Coyote starter wire with the key in the start position. But only if the clutch switch is closed, e.g. pedal pushed down.

If all of this is confirmed and tested exactly as explained, and still not working properly, yes you need to contact Ford Performance. I know their support isn't what it used to be (they've had serious cutbacks in resources) but there's no way I'd wait 2 months for a response. I'd be bugging them every day or two.

Obviously there are other wires to connect -- like the mentioned fuel pump wire, starter wire, cooling fan wire, tach, gauge senders, etc. These are straightforward and shouldn't cause voltages not to be present. The fact that you're not getting the proper voltage to the fuel pump and the starter tells me there's something more going on than just the fuel pump.

Good luck.

[elismithc]

Currently I am circumventing the RF stuff to take variables out since my pump is external and close enough to go directly to the dark green fuel pump wire. From the PDB I have the short cable to the 250a fuse, on the other side of the fuse I have the RF 3 red wires (alternator/ignition cylinder wires), battery cable that goes direct to battery, and a jumper wire down to the starter large post (coyote starter solenoid wire on small post). I have checked voltage on the starter, both sides of the fuse, at the PDB, at the ignition cylinder in the off and run position, all the fuses, and the fuel pump relay, with all of them reading battery voltage.

Throttle body responds to throttle pedal inputs when Ford system is woken up, and CBT switch works as it should.

[edwardb]

Currently I am circumventing the RF stuff to take variables out since my pump is external and close enough to go directly to the dark green fuel pump wire. From the PDB I have the short cable to the 250a fuse, on the other side of the fuse I have the RF 3 red wires (alternator/ignition cylinder wires), battery cable that goes direct to battery, and a jumper wire down to the starter large post (coyote starter solenoid wire on small post). I have checked voltage on the starter, both sides of the fuse, at the PDB, at the ignition cylinder in the off and run position, all the fuses, and the fuel pump relay, with all of them reading battery voltage.

Throttle body responds to throttle pedal inputs when Ford system is woken up, and CBT switch works as it should.

Understand taking the RF variable out of the fuel pump circuit. What it provides is the inertia switch and a built-in wire in the rear harness to the rear mounted in-tank pump. If you don't need either of those right now, going direct to your external pump should work. The rest that you described in theory should work. But if that's not how you're planning to leave it, I would wire it up the way your planning to have it. You don't mention ground. How's that wired? Both the RF panel and Coyote PDB have dedicated ground wires that need to be solid. Very common for electrical problems to be traced back to a bad ground connection.

Two follow-up questions: (1) You say reading battery voltage. With or without any load? A battery can read decent surface voltage but drop way down under load if either defective or not charged adequately. That's why I mentioned previously about battery condition and maybe testing with a different battery. Or test the one you have. (2) You didn't respond to the questions I mentioned confirming how they're wired and voltage on the Ignition Relay Trigger and Starter Motor Request (SMR) wires from the Coyote 16-pin connector. The system isn't going to work if those aren't exactly right.

One other thought after my previous post is the ignition switch. Positive it's wired correctly? Several times in the past guys have had trouble that was traced to the ignition switch.

[Nigel Allen]

It is interesting that you saw 8.9 volts on the dark green fuel pump wire once. If the measurement wasn't in error then it would indicate a high resistance joint somewhere in between the Bat positive input to the PDB (which you have noted as good) and the fuel pump wire. My engine is gen 1 and it is easy to open the PDB for inspection. If that is the case with the gen 3 PDB, check that the fuel pump relay is operating. If not, then the relay is either bad, or is not receiving the control voltage from the ECM. You could also do a wriggle test of the wiring and relays inside the PDB, as well as a 'tap test', using the insulated handle of a screwdriver to tap on the relays and circuit board.
Also noteworthy is the sometimes intermittent operation of the starter motor, which also indicates a potential high resistance joint.
Double check all your wiring, especially grounds. Keep in mind that mass produced items are typically reliable. However the PDB on my gen 1 is what I would consider a low volume device and not particularly robust. The printed circuit board contains a bank of relays interfaced to the ECM. This board could have a bad solder joint or even a crack from an over tightened connection (of course the PDB on a gen 3 may be altogether different). Therefore, I would start with the wiring first, followed by the PDB.

Tip: Remember to measure positive voltages in reference to the matching ground connection. Don't just connect your meter to the chassis or battery negative. If you don't have full battery voltage, it could be a high resistance ground connection.

Best of luck,

Nigel

[elismithc]

I've used both the battery out of my f150 with the 6.2 (750 cca) on a tender/charger during use, and I bought and tried the battery i'll be using for the car which is a group 96r meant for 2018-2020 mustangs. Figured if it can support all the other electrical systems in a mustang, it can support my use. The readings were without load. I believe I was just checking with the battery hooked up but with the ignition in the off position just to make sure I didn't pop a fuse somewhere down the line, but not with the fuel pump or starter running.

The RF ground is on the frame near the RF fuse box. It did read 0.9 ohms from the battery negative terminal to where it was grounded on the frame, i don't know what the RF stuff wants to see, but I believe I saw in the Ford control pack instruction saying it should be less than 0.1 ohms so I was going to move it back to the battery negative terminal as I originally had it and as you suggested.

the light green ignition relay trigger shows the full 12.8-12.9 volts that the battery shows across the terminals, I'm not sure about the SMR wire other than that it triggers the starter in some form - haven't had a second pair of hands as my hydraulic clutch is not setup yet so having to hold the CBT switch by hand. They are wired to the orange efi coil wire and light blue efi crank power respectively, as you mentioned.

I've checked the ignition switch a couple times, referring to the RF instructions and it is as shown. I am not using the brown wire they mention to leave off if the alternator is a single wire alternator.

[edwardb]

Sounds like the wiring is correct. I'm betting you won't find anything wrong with the ignition switch wiring based on what you've described so far. If you jump the starter, e.g. from the large +12V lug on the starter to the smaller one, putting +12V on the starter solenoid, I'm assuming the starter spins continuously? In theory you could hot wire the fuel pump to run from +12V (e.g. from other than the Coyote fuel pump wire) and the jump the starter and the engine should start. Which would confirm the PCM is awake and working. The fact that the DBW and throttle body are communicating would suggest it is. The only other thing I can think of would be to wire the Coyote ground wire directly to the battery ground. I suspect Ford support would make that suggestion to rule out a ground issue. So might as well try that. Assuming that doesn't work, I'm out of ideas and can't suggest anything else other than contacting Ford Performance support. I see I misread your comment and your two week wait (to date) was on a previous issue. Not this one. But I'd still get after them on this if it comes to that and keep trying. Wish I had more. Good luck.

[elismithc]

I'm running a twin disc clutch setup and the transmission input shaft was causing binding somewhere, somehow, but in the process of finding that issue (an issue for another day), I pulled the starter off, and grounding it separately, but still using the key to engage it, it spun no issues.

I did just get done moving the coyote ground back to the battery and no change unfortunately. I did get in touch with ford using their live chat, but I guess my issue required a little more thinking than what they could provide on the spot, so another email sent on their request. Fingers crossed I get a timely response this time around.

[elismithc]

It is interesting that you saw 8.9 volts on the dark green fuel pump wire once. If the measurement wasn't in error then it would indicate a high resistance joint somewhere in between the Bat positive input to the PDB (which you have noted as good) and the fuel pump wire. My engine is gen 1 and it is easy to open the PDB for inspection. If that is the case with the gen 3 PDB, check that the fuel pump relay is operating. If not, then the relay is either bad, or is not receiving the control voltage from the ECM. You could also do a wriggle test of the wiring and relays inside the PDB, as well as a 'tap test', using the insulated handle of a screwdriver to tap on the relays and circuit board.
Also noteworthy is the sometimes intermittent operation of the starter motor, which also indicates a potential high resistance joint.
Double check all your wiring, especially grounds. Keep in mind that mass produced items are typically reliable. However the PDB on my gen 1 is what I would consider a low volume device and not particularly robust. The printed circuit board contains a bank of relays interfaced to the ECM. This board could have a bad solder joint or even a crack from an over tightened connection (of course the PDB on a gen 3 may be altogether different). Therefore, I would start with the wiring first, followed by the PDB.

Tip: Remember to measure positive voltages in reference to the matching ground connection. Don't just connect your meter to the chassis or battery negative. If you don't have full battery voltage, it could be a high resistance ground connection.

Best of luck,

Nigel

In the case of the starter, it was in fact just poor grounds. Did some dremel work on the surfaces and made more permanent attachments of wires. Sounds like a starter should when turning the engine over.

I tested the fuel pump relay and it clicked when supplied power as well as passed a continuity test. But the fuel pump is still not receiving signal even though when I jump where the fuel pump relay goes, pressure jumps up to 65 when pump is running pretty much instantly.

engine started for first time though with jumping the relay.

[edwardb]

In the case of the starter, it was in fact just poor grounds. Did some dremel work on the surfaces and made more permanent attachments of wires. Sounds like a starter should when turning the engine over.

I tested the fuel pump relay and it clicked when supplied power as well as passed a continuity test. But the fuel pump is still not receiving signal even though when I jump where the fuel pump relay goes, pressure jumps up to 65 when pump is running pretty much instantly.

engine started for first time though with jumping the relay.

Good news! Once the correct Coyote wiring was confirmed the ground(s) were the next suspect. So not surprised that's what you found. Looks like you're down to one issue with how the fuel pump is wired into the RF panel. There are different versions of the RF panel and different versions of the Factory Five instructions. Early versions of the RF panel had the fuel pump power and inertia switch relay coil on the same power source in the panel through the fuel pump fuse. Early Factory Five instructions had you clip the one wire and splice the Coyote fuel pump wire. Meaning the Coyote supplied power to both and you could pull the RF fuel pump fuse. Later RF panels have the fuel pump power and inertia switch relay coil on separate power sources in the panel. The latest Factory Five instructions show clipping the wire to the inertia switch relay coil and splicing in the Coyote fuel pump wire. That means the Coyote PDB fuel pump power is only supplying a signal to the RF panel (e.g. energizing the relay) and the RF fuel pump circuit does the heavy lifting of running the fuel pump. This certainly works and if you wire yours that way it would be OK. But personally I prefer the first scheme. So I clip both wires and attach to the Coyote fuel pump power. I see no reason to have two fuses in the circuit. It's all a bit confusing maybe but I'm betting something about how you have it wired is clicking the relay as you said, but power isn't getting through to the actual fuel pump +12V feed. Hopefully my explanation helps to see what you have.

[elismithc]

Good news! Once the correct Coyote wiring was confirmed the ground(s) were the next suspect. So not surprised that's what you found. Looks like you're down to one issue with how the fuel pump is wired into the RF panel. There are different versions of the RF panel and different versions of the Factory Five instructions. Early versions of the RF panel had the fuel pump power and inertia switch relay coil on the same power source in the panel through the fuel pump fuse. Early Factory Five instructions had you clip the one wire and splice the Coyote fuel pump wire. Meaning the Coyote supplied power to both and you could pull the RF fuel pump fuse. Later RF panels have the fuel pump power and inertia switch relay coil on separate power sources in the panel. The latest Factory Five instructions show clipping the wire to the inertia switch relay coil and splicing in the Coyote fuel pump wire. That means the Coyote PDB fuel pump power is only supplying a signal to the RF panel (e.g. energizing the relay) and the RF fuel pump circuit does the heavy lifting of running the fuel pump. This certainly works and if you wire yours that way it would be OK. But personally I prefer the first scheme. So I clip both wires and attach to the Coyote fuel pump power. I see no reason to have two fuses in the circuit. It's all a bit confusing maybe but I'm betting something about how you have it wired is clicking the relay as you said, but power isn't getting through to the actual fuel pump +12V feed. Hopefully my explanation helps to see what you have.

My RF panel is the one with the single orange wire that they tell you to cut at the bus bar, and the photos/directions matched what I had. I am still bypassing this part of the circuit and have the ford fuel pump wire connected directly to the pump. Yes I will probably go through the RF chassis eventually to take advantage of the inertia switch but my twin pump setup also calls for a 40a relay which the ford one is, but the RF is 30a I believe (VMP blower patiently waiting in the living room...). When I mentioned my relay clicking, this was bench testing it by supplying 12v with some alligator clips from the battery, then testing the continuity on the switched prongs. I have never heard the ford fuel pump relay click or activate the pump when plugged in the ford PDB since fixing the ground issues.

I believe I've found the issue... the fuel pump relay is receiving 12 volts, but it is not seeing ground, therefore no relay activation and no fuel pump. Going to tear apart the PDB and see if I can't find out why. Did the same test for the ignition relay and it does see ground and again the engine starts and idles, so don't believe I'm having ground issues with the main ground.

[elismithc]

Final update: I guess when I was pulling the relay on and off, it made the pin into the pdb get loose for the ground. Pulled apart the PDB and checked on the backside that there was a connection. Everything works now, thanks for everyone's input.

[Jryasko]

Glad you got this resolved. Trust me after 40 plus years of being a Heavy Equipment Mechanic, many times one has to go back to the beginning and start over with troubleshooting. Many times I have seen people overthink a problem and get more confused. KISS keep it simple stupid is something to keep in mind.

[Nigel Allen]

Great outcome as a result of your persistence. Sounds like the PDB is still a little flimsy like the gen 1. Having said that, most Coyote builders don't get the trouble you have had. Hopefully it's the end of your problems. There is so much to like about these engines.

Cheers,

Nigel

[edwardb]

Great outcome as a result of your persistence. Sounds like the PDB is still a little flimsy like the gen 1. Having said that, most Coyote builders don't get the trouble you have had. Hopefully it's the end of your problems. There is so much to like about these engines.

Cheers,

Nigel

I agree. Good outcome. I wouldn't characterize the Gen 2 (and Gen 3, they're the same) PDB's as flimsy. Unlike the Gen 1, they're no longer a custom part but rather a derivative of an OE part like used in many Ford vehicles.

https://hosting.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Coyote%20Engine/.highres/IMG_3565_zpsygpc8uzr.jpg?width=590&height=370&fit=bounds (https://app.photobucket.com/u/edwardb123/a/9fc5592b-f6c0-442e-87aa-319e7e5e159e/p/c5e4f736-854d-4575-9229-155b1c42ec69)

[Nigel Allen]

G'day Paul,
out of interest, do you have a pic of the inside of the gen3 PDB? Keen to see how they are done.

[edwardb]

G'day Paul,
out of interest, do you have a pic of the inside of the gen3 PDB? Keen to see how they are done.

Hey Nigel. I don't. And kind of buried in the Coupe to try to take a picture. Check page 21 in the Ford instructions. Shows a diagram of what it looks like. https://performanceparts.ford.com/download/instructionsheets/FORDINSTSHTM-6017-M50B.PDF. Pretty standard stuff.

[elismithc]

G'day Paul,
out of interest, do you have a pic of the inside of the gen3 PDB? Keen to see how they are done.

138460

[Nigel Allen]

Guys, thanks for the info. The current PDB is substantially better than the gen 1 PDB.