In the past 8 days, I have had my truck die or almost die about 5 times. Today, it wouldn't restart. Luckily my wife was with me and I was able to crawl under the truck to check the fuel pump. The first couple of times she cycled the key on, the pump wasn't running. About the third time she tried, the pump started pumping. I got back in the truck and it started normal and ran normally.

Is this a bad pump? or is this a bad switch telling the pump to turn on? Any help in troubleshooting is appreciated. I don't want to buy a new pump if it is just not getting a signal to turn on.

 

I would keep driving to a minimum, low fuel pressure is going to take it's toll on the injectors in short order.

Fuel pump relay should be under the hood in the fuse block, might be #302? Check owners manual, probably labeled as the HFCM
HFCM fuse is there as well, if not then check under the steering column.

 

When was last time you replaced both fuel filters with OEM?

 

Fuel filters changed late Oct. about 6000 miles ago. How would clogged fuel filters cause the fuel pump to not run? Pulled codes just now and I have a P0232.

 

Swap your fuel pump relay with another relay.


Ed

 

Fuel pressure is extremely important! Below 50 at the secondary filter is going to starve injectors. Of course start with the basics like clean & tight battery connections. Swap relay with another. Test voltage at the pump connector and do a wiggle test while reading volts.

When I put my new pump in I was amazed how much more audible it was. Could never hear the old one. New one can be heard distinctively in the cab when I flip the key.

 

I'm still fighting this issue. I'm going to wire up a LED light to where I can see it to know if the fuel pump is getting voltage. I believe that the fuel pump isn't getting the message to turn on at start up sometimes. I have a new fuel pump, and it is too quite to hear from the cab with the window rolled down in my driveway. Much less when I am stuck on the side of the road. I discovered the fuel pump to be the issue by crawling up under the truck after it died. I left the key in the run position and there was nothing going on at the pump. I had my wife cycle the key several times and after about 5 times it finally started pumping and the truck fired up and ran great. Every time since I pull over to a place where I can safely get under the truck. I cycle the key until the pump runs then start it up and continue on my way. Sometimes it turns on the first try, other times 2nd or third attempt.

I hear the message to switch out the HFCM relay, but a reputable source on another site said that if you look at the wiring diagram that relay doesn't send a signal to turn on the fuel pump. He said that the relay that sends the signal to the fuel pump is hardwired into the under dash fuse panel, and you have to change the entire panel. If this is the case, I may hot wire a toggle switch to the pump instead. I will see if there is an accessory wire that I can tie into that will not be hot once the key is turned all the way off. Hopefully, this would be just a short-term temporary troubleshooting tool, but I'm weighing the pros and cons.

With the LED light, I'm wanting to test my theory that the pump hasn't stopped running during a drive, but it just never turned on at start up. If I can prove this, then maybe I can get to the bottom of why it's not working properly, or prove it wrong and suspect the pump or something else is bad if it stalls and the LED stays lit. I'm thinking the computer or relay. I may need to return to stock, or try a different tune for a while and see if it helps. I have Matt's custom tunes. Gearhead Auto.

I think that every time this has happened to me, the truck started but the fuel pump didn't. When it finally runs out of pressure, the motor bogs down. I'm recognizing this now as soon after I start it, it will feel as if there is a miss and lower than normal power, but I can get up to highway speeds if I ease into it. I will not do this anymore in hopes to not further damage any injectors. I'm getting tuned into what it feels like at start up so I don't continue to drive it very far and screw up my injectors. This has happened about 8 times in two weeks. Each time was a short distance from where I started the truck.

 

The 6.0 will run without fuel pump pressure. Provided the fuel system is air tight, the injectors become the fuel pumps. My AD2 fuel pump failed 3 years ago, due to fuel leaking into the pump motor, while I was at work. Did not know until the AD2 yellow warning light came on but the 6.0 started and continued to run with enough power to move. So I drove it home and fixed the problem.


I have abused my injectors pretty bad in 138,000 miles. I have run normal fuel pressure with the OEM pump, did the BB mod and installed the GDS regulator spring that raised the fuel pressure to 105 psi. Sent my FICM off to Ed and when I got it back weird stuff started happening over a 2 year period. Sent it back to Ed and he said it was fine. Upgraded to the Atlas 80 tune and after I got it back I discovered the FICM power relay was probably deteriorating over the two year period without me knowing it causing the weird stuff. Have never had an injector issue during this abuse. X has never run better.


I looked at the fuel pump wiring diagram and after the fuel pump fuse is the pump relay followed by the inertial cutoff switch. If the pump does not turn on, I would cycle the ignition switch several times to see if it does turn on. I would swap the relay and check the inertial switch. The pump draws a lot of current and the relay contacts are possibly pitted or burnt. The relays can be taken apart to check.


Ed

 

Thanks Ed,

I will switch this relay out as it could be the culprit, but I am going to wire up the LED so I can pull over and turn off the truck when the fuel pump is not running. It's good to know that your injectors were not ruined. I have the Blue Spring, but I don't have fuel pressure gauge.

So the FICM you got back from Ed wasn't the culprit, but the FICM relay was? I replaced the relay when I got my upgraded Atlas 40 FICM from Ed. It is possible that the new relay wasn't 100%. I will put in another new one. I have thought about asking Ed if he thought my troubles could be FICM related. My voltage is constant 49 -48.5 volts and my alternator is constantly providing 14.1 volts running. Oil pressure is always solid.

Thanks again for your input. I don't want to lose the EX, but if these gremlins continue, I will grow weary of them for sure.

 

When my fuel pump went out truck was running fine,been ideling for about 20 mins untill i pulled out on road,lost all power,rpm went down to about 450 for few secs then died, kept trying to start,heavy traffic area so could not hear anything, got pulled to my house and cycled key but heard pump come on go off fast,kept doing this and it went a full cycle on as normal,cranked truck run great till got ready go on road,died again,could not hear pump thru a full cycle again so new pump went on and never looked back,been fine ever since and can hear new pump loud now no problem,oreilleys or advance with lifetime warnty.

 

P0232 generally means an internal short in the hfcm. If the wiring to the pump looks normal and not damaged,, I'd be swapping the pump. I've had quite a few of these with intermittent issues.

+1 on the Oreillys. I sell a bunch of them. The Oreillys one actually might be an oem one. It comes with the fuel heater delete harness (and the harness is exactly like the ford one,, even says made in Mexico. The only difference looks to be they grind the ford part number off of the black holding bracket).

 

Update, on intermittent fuel supply issues.

I am fairly confident that most of my issues thus far have been from the fuel pump not running on occasion. I tried rigging up a LED test light to let me know when the pump was getting voltage, but for whatever reason, my LED would only flash when I would turn the key on or off. Because of tapping into the wiring harness for the LED test light, I tried a brand new wiring harness. This actually seemed to help, and it seemed as if the pump was somewhat more reliable, but on occasion, it still was acting as if there was low fuel pressure from the pump not running. I was also noticing some surging that was a different symptom from when the fuel pump wasn't running. Friday night I drove about 30 miles and had continuous issues with surging and low fuel flow symptoms coming and going.

Saturday, I replaced the fuel pump and HFCM. The fuel filter that was removed was very clean, in good condition, and a Motorcraft filter. I had been meaning to swap out the drain plug since the last filter change, and it is possible that it could have been sucking in some air. The o-ring and the plug itself were both in pretty bad condition.

Would air being sucked into the fuel supply cause the surging symptom?

Saturday, after replacing the HFCM, the first test run was positive, and I was feeling really good about it, but it was less than two miles and all below 45 mph. Later, on a longer run, I had some of the surging issues at highway speeds and I was really disappointed. Sunday and this morning all seems fine in a mix of driving conditions, but very few miles. Less than 10 total. I guess only time will tell.

If air in the system will cause the surging issue, then it is possible on the second run there was still some trapped air from the new HFCM that made it's way up to the injectors. I also suspect the inlet connection to the HFCM may be a source of air being sucked into the system.

This weekend, I am going to run a fuel pressure gauge, and drop the fuel tank. I know that I have lost the strainer on the fuel sending unit, and I will do the harpoon mod, as well as clean out the tank. Last option before taking it to the shop is to replace the fuel hose and connector from the tank to the HFCM. It didn't snap into place with an audible click and I suspect it to be another place where air could come into the system. I am not smelling diesel, and I see no leaks, but my thought is that under acceleration there could be some negative pressure on the line from the tank to the HFCM that is greater than any positive pressure seen in that line. I guess I could try and put a little positive pressure on the fuel tank or once I drop the fuel tank concentrate on that fuel line and put some pressure on it to see if it leaks under pressure.

Please advise on what would cause the surging issue. It isn't abrupt, but the motor revs up higher than the amount of pedal that is being given. It is always under a steady pedal. It happens at slow speeds and highway speeds.

 

Did you ever figure this out? Having the same issue fuel pump works intermittently. Replaced fuel pump, filters drained my tank to E and filled up with new diesel. Truck will turn on at times and sometimes will take multiple cranks. Please let me know thanks!

 

I replaced the fuel pump and that cleared it up. I replaced the whole filter housing and all. I hope you get it figured out.