Excursion fuel issue

Reply Subscribe

Thread Tools

Search this Thread

Feb 23, 2019 | 04:00 PM

#16

Lance Helmert

Laughing Gas

Joined: Sep 2012

Posts: 880

Likes: 13

From: Northcentral Wisconsin

If your filter was completely plugged, I would replace the filter again. I would also run a fuel system cleaner . I like Seafoam or Amsoil PI.

Feb 23, 2019 | 08:36 PM

#17

R&T Babich

Fleet Mechanic

Joined: Feb 2011

Posts: 1,812

Likes: 88

From: Thousand Oaks, CA

Quote:

Originally Posted by Gjcb1976

..... Plugs and coils are all new within the past 12,000 miles. ....

What plugs and COPs did you install? Motorcraft plugs and Motorcraft or Denso COPs?

Feb 23, 2019 | 08:38 PM

#18

thor363

Fleet Mechanic

Joined: May 2017

Posts: 1,313

Likes: 102

From: TN

After all this, he's going to come back and say, "Hey! I found a bad battery cable connection!"

Feb 23, 2019 | 08:56 PM

#19

R&T Babich

Fleet Mechanic

Joined: Feb 2011

Posts: 1,812

Likes: 88

From: Thousand Oaks, CA

Quote:

Originally Posted by seijirou

.... Another cause that is down-stream of the ignition switch is the main power relay.

What relay is the "main power relay"?
The PCM has a relay in the CJB.
I think the 2003 is the same as our 2002, the Fuel Pump relay is soldered on the bottom of the CJB.
The RD wire from the battery goes to a Junction Block, then on to the CJB with a fusible link in the wire.

Feb 23, 2019 | 09:14 PM

#20

R&T Babich

Fleet Mechanic

Joined: Feb 2011

Posts: 1,812

Likes: 88

From: Thousand Oaks, CA

Quote:

Originally Posted by Gjcb1976

.... I just can't figure out the intermittent stuff. I've had fuel pumps go out before and they just quit.

I've read several times about "intermittent" fuel pumps, it's just a pump and if it is worn can get sticky causing fluctuations in output.
The Fuel Pump relay contacts can get corroded from use and reduce the current supplied to run the fuel pump motor.
The voltage may look fine, but the current capacity thru the contacts can be low.
The Fuel Pump relay is rated at 20A and if I measured our pump's resistance properly it is a 15A load..
Another intermittent might be a poor connection at the Crankshaft Position sensor or a flaky sensor.
I think that sensor is used by the PCM logic to power up the fuel pump when starting, and when running keep the pump powered and of course fire the plugs and injectors.

Feb 23, 2019 | 11:11 PM

#21

Gjcb1976

Thread Starter

New User

Joined: Feb 2019

Posts: 13

Likes: 0

Thanks, guys! You have given me so many things to look for! One of you asked about the plugs and coil I used. I think it was the Denso, but I need to go out and check. I'm still chasing the issue down, but it is NOT the battery cable. :-) That was actually the first thing I checked because that was the issue with my wrangler last year. Anyways, I'm at the point I am just cleaning everything I can. Throttle body, IAC, MAF, fuel regulator...... I'm also checking wires and electrical connections. I will add all of your suggestions too. I keep going back to that plugged fuel filter. I couldn't blow ANY air through it when I took it off. I replaced it with a new one and then replaced that new one again tonight. It had only been driven about 100 miles, but it was pretty clear.

Feb 25, 2019 | 10:48 AM

#22

seijirou

Cargo Master

Joined: Aug 2012

Posts: 2,840

Likes: 921

From: Kaufman TX

Quote:

Originally Posted by R&T Babich

It very well could be in the CJB and Ford may not consider it "serviceable" but soldered to the board or modular they all still function and can fail in the same way. The PCM relay is definitely more specifically what I have in mind. Typically there's a single main power relay upstream of the PCM and other things like the injectors and the coils, so I apologize if that isn't the case for this truck. The PCM relay would be what I was swinging at though, thanks for the correction.

Feb 25, 2019 | 10:59 AM

#23

Gjcb1976

Thread Starter

New User

Joined: Feb 2019

Posts: 13

Likes: 0

Any idea where the PCM is located on the 2003? I've been searching online and haven't had any luck yet.

FTE Stories

Ford Trucks for Ford Truck Enthusiasts

Top 10 Ford Truck Tragedies

Joe Kucinski

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

Brett Foote

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Michael S. Palmer

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Verdad Gallardo

10 Best Ford Truck Engines We Miss the Most!

Joe Kucinski

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Brett Foote

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Michael S. Palmer

10 Most Surprising 2026 Ford Truck Features!

Joe Kucinski

Top 10 Ford Trucks Coming to Mecum Indy 2026

Brett Foote

5 Best / 5 Worst Ford Truck Wheels of All Time

Joe Kucinski

Feb 25, 2019 | 11:26 AM

#24

R&T Babich

Fleet Mechanic

Joined: Feb 2011

Posts: 1,812

Likes: 88

From: Thousand Oaks, CA

Quote:

Originally Posted by seijirou

I thought you meant a relay for the PCM, just wanted to clarify.
There are several "Hot at all times" relays, i.e. fuel pump, AC, headlights, seats, etc.
Seems odd the PCM relay does not have a fuse between it and the battery.
Fords idea of soldering the fuel pump relay to the bottom of the CJB is just lame.
The fuel pump relay gets opened/closed twice as often as any other relay per trip - once to prime the fuel rails and again to run.
And now that the relays are getting worn out the "serviceable" replacement assembly, the CJB, has been discontinued.