Fuel Pump cutting in and out.

[ClaytondeG]

Hi everyone!

Most issues with my SHO I can solve with some searching these forums, but this one is beyond me. The car has a bit of a stutter at low RPM but is still drivable. I have just been telling myself that this is due to there being oil in the spark plug wells and I will fix this when I do the valve cover gaskets. (Just thought I’d include this in case it is related)

Anyway, the real issue comes once the car gets up to temp. After about 20 minutes of driving in these hot summer days the car will start to really lose power. For a second at a time it will have no power at all, then back to normal, then back to no power. If I park the car when this starts to happen I can hear the fuel pump stopping and starting again. Likewise, the relay box clicks each time the fuel pump cuts out. This makes me think that the computer is actually telling it to shut off. I tried checking the ignition wiring to see if it was shorting and turning off the car spastically, but that wasn’t it. I also thought it may be the crank position sensor because of the hot weather and loss of power, but I KNOW that the fuel pump is cutting in and out. Any help at all diagnosing this would be greatly appreciated!

Here is a video where you can hear the whirring of the pump cut in and out and the relay clicking each time:

 

[ClaytondeG]

Just to add. I am not getting any engine codes at all for this. Also, the frequency of the pump cutting out in the video is pretty fast. But if I let it run like this for a while it will get to a full second between shutting down until it if off for long enough for the car to stall.

I checked fuel pressure when it is cold and running correctly and there is no issue.

 

[ClaytondeG]

My bad, it’s a 1990

 

[luigisho]

There are relays in the CCRM- relay module- on top of the radiator that includes the fuel pump. It has a large letter on top and its replacement must match it to operate properly. This is if that is the issue or the only issue. If you think there is an issue with ignition from oil fouled plugs or wires I would also address that with fresh gaskets and new plugs and wires. It's tough to pinpoint running issues with more than 1 malfunctioning area. I usually try and hunt down a used ccrm. I don't think I ever got a bad one, but I am sure that could or has happened to someone.

Looking at your video you would need one with the M on top. There are slight differences with different lettered models.

 

[rubydist]

Since you can hear the ccrm clicking when the fuel pump is turning on and off, its possible that it is not the ccrm that is bad, but rather the pcm or the wiring between the pcm and the ccrm. All of those appear to be culprits imho.

 

[NoSlo]

You just need to back-probe the appropriate pins on the IRCM module (CCRM on later years) with a multimeter, after ensuring the computer and relay module's ground connections are solid.

With the clicking, you might also find fault in another part of the CCRM besides fuel: The power it provides to the EEC and other modules when the key is on. CCRM pin 24 (red) is the power output for everything engine.


Ground the fuel pump terminal at the diagnostic connector so pump runs in key-on-engine-off.

• Is the power for the pump working good and constant? (Pink/Black, pin 5, should be constant 12V)
• If not, is the CCRM's power supply good and constant? Check pin 8 (EEC relay fuse 30A) and pin 12 (cooling fan 60A fuse) on CCRM for 12V.
• Is the ECU signal for pump engagement getting to the CCRM module? (CCRM pin 11, ECU pin 41)
• Is the ECU ground for pump engagement getting to the CCRM module when running? (CCRM pin 18, ECU pin 22.) This is the same circuit/wire as the diagnostic connector terminal that you ground. (see that buffered 12v is pulled to ground).

• Can the ECU detect that the fuel circuit is working? (fuel pump monitor, Pink/Black, ECU pin 19)

Cutting out at high temperature, or dying completely until it cools, is crank sensor, but you have another obvious problem first. You could even have a wiring short that isn't quite bad enough to pop a fuse.

 

[ClaytondeG]

Thanks, I’m going to be probing these connections this weekend when I get the chance. I read somewhere else on this forum that the 1989 and 1990 SHO has a low speed and high speed fuel pump relay. However that doesn’t really seem to be the case from the “M” code pin out. Does somebody know of that’s the case and if so which pin is the high speed control and which is the low speed? Thanks

 

[Imnotsureyet]

You just need to back-probe the appropriate pins on the IRCM module (CCRM on later years) with a multimeter, after ensuring the computer and relay module's ground connections are solid.

With the clicking, you might also find fault in another part of the CCRM besides fuel: The power it provides to the EEC and other modules when the key is on. CCRM pin 24 (red) is the power output for everything engine.


Ground the fuel pump terminal at the diagnostic connector so pump runs in key-on-engine-off.
View attachment 78732

• Is the power for the pump working good and constant? (Pink/Black, pin 5, should be constant 12V)
• If not, is the CCRM's power supply good and constant? Check pin 8 (EEC relay fuse 30A) and pin 12 (cooling fan 60A fuse) on CCRM for 12V.
• Is the ECU signal for pump engagement getting to the CCRM module? (CCRM pin 11, ECU pin 41)
• Is the ECU ground for pump engagement getting to the CCRM module when running? (CCRM pin 18, ECU pin 22.) This is the same circuit/wire as the diagnostic connector terminal that you ground. (see that buffered 12v is pulled to ground).
• Can the ECU detect that the fuel circuit is working? (fuel pump monitor, Pink/Black, ECU pin 19)

View attachment 78733

Cutting out at high temperature, or dying completely until it cools, is crank sensor, but you have another obvious problem first. You could even have a wiring short that isn't quite bad enough to pop a fuse.

Your post is great. Very to the point and very easy to fallow. I have the manual for the 1992 taurus/sable witch includes the SHO. Electrical & Vacuum Trouble Shooting Manual but I couldn't fallow it and get what you pointed out in a relatively short few paragraphs. It would have taken me a few days to have been able to figure out all of that even having the manuals I have. I and I have the cd manual that covers the same car's all Ford Taurus SHO, Taurus and Sable 1992. Cost me but it was worth it I just wish Could fallow it like you can

 

[Evan Silletto]

I had a similar issue and it ended up being the throttle position sensor - of course with these cars the same symptom can occur from so many different causes…
I also suggest examining / cleaning all your ground paths, especially those that lead to the DIS (like the lower bolts that mount the crossover tube) and the coil pack - most of the issues I have experienced with my 89 have been at least partially related to grounding… so mich so that I have added a web of auxiliary ground wires that connect my V- to my DIS, the passenger side firewall, the rear of the intake manifold, the CCrM, the coil pack, the MaF and few other misc points — adding these paths made a bigger difference than I could have ever imagined.
Also camshaft position sensor can make the car do what you described if there is enough oil in it…

 

[Imnotsureyet]

Thanks, I’m going to be probing these connections this weekend when I get the chance. I read somewhere else on this forum that the 1989 and 1990 SHO has a low speed and high speed fuel pump relay. However that doesn’t really seem to be the case from the “M” code pin out. Does somebody know of that’s the case and if so which pin is the high speed control and which is the low speed? Thanks

I don't know about the 98 or 90 but the 92 has a low and high fuel pump relay the pins are low 22 and high 41

Thanks, I’m going to be probing these connections this weekend when I get the chance. I read somewhere else on this forum that the 1989 and 1990 SHO has a low speed and high speed fuel pump relay. However that doesn’t really seem to be the case from the “M” code pin out. Does somebody know of that’s the case and if so which pin is the high speed control and which is the low speed? Thanks