Hello everyone,
I've searched, read and tried some of the diagnostics that were listed in other threads. I thought I saw a post that included the minimum or maybe it was typical voltage for the pump to run. Maybe someone can point me to the thread or even help me with the information needed.

I have a 2004 F-350 V-10 Crew Cab Long Bed Dually with 95,000 miles on it.

I drive the truck occasionally but had to start driving it as a daily driver. It has had a hot restart issue for a couple of years. I drive it in the morning with no issues. In the afternoon I have learned to do my loop to pick up my kids and leave the truck running wile I wait. This week I just spaced out and stopped to get the kids a treat. It restarted fine, I patted her on the dash and thanked her for starting. Then the idle got rough died. It started a few times but never idled good and then would die. Now there is no life, just cranking. Typically in this situation I could let it cool down up to 90 minutes and it would start. This time it hasn't restarted even after 4 days.

Specifics:
Engine restarted, stumbled and died when hot. No start condition now.
Can hear a relay click on for 2 seconds and then off when ignition in "run" position.
Checked for power at the inertia switch with test light. Power noted for the 2 seconds when ignition in "run" position but test light looked dim.
Checked voltage on both sides of inertia switch. During first test 9.8v - 10.4v noted on either side when ignition in "run" position and 6.2v after 2 second pulse ended.
Changed fuel filter as suggested in one thread. No change.
During second test 9 volts noted during 2 second pulse when ignition in "run" position. Now 0 volts present after 2 second pulse ended.
Checked for voltage on frame rail and noted 8.5v -9.0v when ignition in "run" and "start" position. Still 0 volts present after 2 second pulse ended.
No fuel squirts out of fuel rail schrader valve. I can not hear the fuel pump at all.

I want to make sure I'm doing things properly and don't want to automatically assume the pump is the culprit
What is the minimum voltage the pump "should" run at?
Does it sound like the relay is failing and may have taken out the pump? If so, I think mine is on the back side of the fuse relay box but not sure.

Thank you in advance for any help or advice.

 

Run a wire from fuel pump ground straight to battery negative, see if you get 12 V. Might have high resistance at the fuel pump.

-- Dave

 

If the voltage at the inertia switch isn't right, it's not an issue with the fuel pump ground. It's an issue with the power from the fuel pump relay being inadequate, usually from a failing relay.

Unfortunately, the FP relay isn't a simple replacement, it's actually soldered into the CJB internally. It's pretty simple to scab a new relay around the CJB. It's been documented several times over the years.

 

High resistance as in a failing or shorted pump motor?

I put a battery charger on the truck this morning since all the tests and cranking might have run it down a bit causing the 10.x volts at the inertia switch.
It still cranked strong with no hesitation prior to that but just trying to eliminate another possibility.

I forgot to mention in my original post that when I disconnected the inertia switch and applied a jump wire that it arced a bit.
I tried running a test wire from the positive battery terminal to the wire feeding the pump at the inertia switch to see if that would stop the arcing but it didn't.
The voltage through the new cable reads 11.7 volts during 2 second prime and crank to start but back to reading 6.2v after 2 second prime is done.
Does this sound like a shorted pump? Should I still try to run a test ground from the battery to the pump or do you think it is unnecessary at this point? If so, is that at the pump body or tap into the negative wire at the pump harness? I'll need to go get new wire to try the ground test wire.

 

I originally believed that it was the relay from reading some of the posts. Obviously I wanted to do some diagnostics to confirm but I'm a little over my comfort level and knowledge. I will continue though.

I was pretty sure I found the relay(s) on the rear of the CJB but wanted to get a used
one to rebuild first. Unfortunately, I ran out of time. I will look for the workaround relay post.
Thanks guys.

 

@projectSHO89 Can you explain how the integrated Fuel Pump relay (in CJB) works with the Fuel Pump relay behind the radio? Is it dependent on year, or are there 2 relays? Thanks.

@SuperDutyTim ProjectSHO89 knows what he is talking about... I would follow his advice But, the fact you're not getting a full 12V at the inertia switch is something to continue following. I would check your grounds in general to see if you can get a full 12V. I had read in another post about jumping a wire over to the inertia switch and see if that fires up the pump:

 

There is only one fuel pump relay, regardless of the model year. For 99-01 Super Duty, it was behind the radio. An electrical redesign that occurred for the 2002 MY moved the FP relay INTO the CJB for several years.

 

Thank you for the clarification!!

 

Hey Baja, I did get the impression that ProjectSHO89 is knowledgeable from the other posts that I was reading but it's good to hear validation from another member.

I tried to jump the inertia switch and it arced. I then ran a new wire from the positive battery terminal to the pink/black wire (pump side) of the inertia switch wires and it arced again. It would show the same voltage either way at 11.7v during priming and 6.2v at rest. When it was jumped I did notice heat building up on the connection. I never got around to hooking up a new ground wire as recommended by @Djosbun after seeing higher voltages.
I was finally able to get my friend who's an electrical engineer over to help me.

The first thing he had me do was clean my battery terminals and posts even though I didn't see any corrosion. (I know better and should have done that sooner)
I'm not sure if my multimeter may have been misreading due to that or another issue. His multimeter was reading voltage from 11.9v to mid 12.2v at the pump during the 1-2 second prime and 6.7 at rest. We're still a little baffled about that 6v present after the priming.
He tested the pump with a new wire run to the battery, a good ground and it was pulling 15-16 amps on the circuit. The pump was showing 0.8 ohms of resistance. He could hear a click in the tank but the pump either didn't spin or spun so slowly that we couldn't hear it. After several primes and cranks I still had no fuel at the rail. We are assuming that may be why we're getting 6.7 volts after priming is done. He said he feels 95% comfortable calling it a bad pump. Either way, I have the bed off and almost 100,000 miles so I'm okay with putting in a new pump at this time. I hope that fixes it. I'll keep you updated.

Any recommendations on a good reliable pump? I'm considering the Delphi pump and calling the dealer for a price on the factory pump.

Also, we are going to install a volt meter on the fuel circuit and possibly run an outside relay since mine appears to be the integrated CJB style.
Thanks for your input @bajaphile
Thanks to @projectSHO89 for his wisdom too.

 

I never ran the ground since after cleaning the battery terminals and quick charge the voltage came up. My friend tested the voltages with his nicer meter and was getting high 11v to low 12v at the pump. I will keep that in mind though.
Thanks for your input!

 

Your pump is confirmed defective (partially shorted internally). It should never draw that much current. Don't be surprised the the FP relay or one (or more connections downstream from it suffered heat damage.

The 6.x volts is coming from the PCM from what is supposed to be an input port for the PCM to monitor the fuel pump's power feed. I'd consider it to be a poorly designed input port that has what I assume to be a bias voltage is actually presenting on that pin. Your EE friend can likely figure out my gist and explain it further. My usual response is to simply advise ignoring it as a "red herring".

 

Thanks for your response @projectSHO89 . I will proceed with a pump replacement. Any recommendations for a pump? The dealer is combing through all of the pumps as we speak to figure out the right one for my truck. I think she said there were 40ish pumps.

 

Sounds like you narrowed it down! If it were me, I'd stick with the Ford Motorcraft pump! Dealer should provide you with a part number. You can probably then find it a lot cheaper through a dealer outside of California.

 

My pump was replaced with one from NAPA. Truck runs much better now. The shop told me they use a rubber hammer to rap the tank rather than tow vehicles to the shop when the fuel pump is not working. Shaking the pump usually makes them work.

 

Super Duty Tim- I know it is a two year old post, but I have the exact same issue/voltage etc. Also tested exactly as you have minus at the pump. Planned on that tonight. Did it end up being the pump, or did it end up being the relay?