96 Pace Arrow Ford 460 no start.......no fuel?

[mikeylikesit]

Went out to do my monthly engine start, albeit a week late, and she won't start!  Cranks fine but won't fire. Pulled a plug wire to verify spark, it's good.  Don't smell a whiff of gasoline, as I normally would when opening the doghouse.  Got out the service manual, next step on the list is the Fuel Pump Cutoff switch. (verify power in, and power out)  However, I can't find it! 

anybody have a problem with this "inertia switch" flaking out?  The rig has not moved in a couple of months, and ran just fine 5 weeks ago......so I'm kinda perplexed.    First things first, I gotta find this switch.

thanks in advance for any pointers!

 

[Lou Schneider]

If your engine is fuel injected, it has a Schrader valve (like a tire valve stem) in the engine compartment where you can check the fuel pressure.  Should be 40 PSI or higher with the engine off key on and the engine stopped.  If you haven't replaced the in-tank fuel pump, the original design was known for failing unexpectedly.  Ford fixed this around 2000.  Do you hear the pump buzz when you first turn on the key?  If so, it's getting voltage and the inertia switch is OK.

On a pickup truck the inertia switch is up under the dash on the passenger sidewall.  I don't know where it is on a Class A, though.

 

[Larry N.]

If you haven't replaced the in-tank fuel pump, the originals were known for failing unexpectedly.

As a side note: We had the in-tank pump on a Crown Vic die on I-70 in eastern Colorado a number of years back. We were towed to Burlington (60 miles or so east of where we broke down) and the Ford dealer there told us that running below about 4 gallons of fuel several times can cause that failure because the fuel is part of the cooling strategy, so you're not supposed to use that last bit.

Apparently the manufacturer, in spite of telling you about a 19 gallon tank, fails to tell you that you should always leave that extra in there to give the pump adequate cooling, thus reducing your expected range. I don't know whether other manufacturers (or even all of Ford's vehicles) have that problem, but it's something to keep in mind for the future.

 

[mikeylikesit]

thanks folks!    I found the inertia switch, it's located under the steering wheel, drivers side, on the bracket the column mounts to; behind a sheet metal shroud (around the brake and e-brake pedal.)  Does not appear to be in the "tripped" condition. 

found the fuel pump relay (#2 in the fuse box) and swapped it out for known good one, but that didn't fix it.  Hmmmm..... not sure what to check next.....but will look for the schrader valve to see if I have fuel pressure.

might have to crawl under the tank and have the wifey turn it on to see if I can hear the pump come on....

 

[mikeylikesit]

so......found the schrader valve :  no fuel pressure, with the ignition on.    Is there a separate "injector pump", or does the the fuel pump in the tank provide the 40# if pressure?



.....and then to jump ahead,  is the fix to abandon the "in tank" pump, and cut into the fuel line and add (a new) electric pump?  oh, the joys of owning an older RV............

 

[Lou Schneider]

Nope, you should have pressure at the Schrader from the in-tank pump.  If your fuel tank is mostly empty, it's not that hard to drop it and replace the stock pump.  Or you may be able to cut an access hole in the floor of the RV and get to it that way. Current pumps don't have the sudden failure problem.

I don't think you can pull fuel through a stuck pump, it's a multichamber design so there may not be a path through it if it's not turning.

 

[Henry J Fate]

It would be a good idea to either test for voltage to the pump or send the needed 12 volts to be sure the pump is bad before dropping the tank.

 

[Mark_K5LXP]

I had a similar thing happen with my aging pickup.  Every now and then, just wouldn't start.  No fuel pressure on the rail.  Started carrying a voltmeter around with me and finally caught it in the act, ended up being the fuel pump relay.  It had a fatigued solder joint inside of it and just the act of opening the fuse box it would work again, making tracing it difficult.  Measure voltages and prove the fault before you go dropping the tank changing parts that aren't bad.

Mark B.
Albuquerque, NM

 

[mikeylikesit]

thanks all!  Unfortunately, there is no way for me to prove voltage at the pump (connector) without dropping the tank.  I have voltage to the wire going back to the pump, but the wire is inside a wire loom from the "cab" area going back to the pump. 

Plan now is to pump out the fuel and drop the tank.  At this point I'm just going to change out the pump anyway, due to the reports of "known issues".  I still can't believe I'm lucky enough to have it fail sitting in the driveway!

 

[Barnibus]

A 24 year old vehicle. Unless you know for a certainty that the fuel pump was recently replaced, that would be the logical next step.

I suggest that you pull both chassis and House Battery connections and firmly ground the chassis AND the tank before messing with it.

An empty fuel tank can be more dangerous than a full one. 

 

[mikeylikesit]

so, finally getting around to dropping the tank.  What to do with 75 gallons of fuel was a challenge.  Then, whoever put in the jack system most certainly did not think about the possibility of the fuel tank needing to be dropped.......removed (mechanically, not hydraulically) the jacks, but the jack mounts are welded in place.........obstructing the bolts to one of the tank straps........but I digress.....ugh. 

Anyway, got past those challenges and am ready to change out the fuel pump unit.  couple of questions......

there is no modular connector for the wiring. Guess I have to cut and paste.........fortunately the new Motorcraft fuel pump came with some instructions on how to do this....so I think I have that handled.

1. what is this other fuel line and device (red arrow in the photo)?  ( it is NOT connected to the pump/gauge sending unit)
2. the smallest fuel line of the 3 connecting the pump is just hose clamped to the pump.  Is this a hack job?  should I correct it if so?
3.  Where is the generator fuel feed?

Thanks in advance for any insight.

 

[ChasA]

I think it's part of the evaporative loss system, which captures fuel fumes and returns it to the fuels tank.

 

[mikeylikesit]

well, it may not be the pump..... now that I have access to the wiring for the pump, I got out my test light and tested, and found no power at the pump connection. 

also, it looks like this is NOT the original fuel pump, as the pump itself (with sending unit) is a FOUR wire, which has been spliced into the 3 wire chassis loom. The instructions in the new fuel pump discuss this.


So, back to the drawing board, and troubleshooting. Noticed that the relay, when I pull and replace the fuse (with key on) , closes (clicks) and then 1 second later, clicks again. (it opens)  clipped the test light on the connector to the inertia switch, and operated the ignition switch. (OFF to ON, but not cranking)  Sure enough, when the ignition is turned on, the circuit is hot for about 1 second, then turns off.  ON to STARTING got the same result, test light on for about 1 second, then off.

I swapped out the relay for a known good one, same thing.  So, got the wifey off the couch and had her operate the ignition,  while I got back and listened for the pump to run, which it did not.  (at least I couldn't hear it, or feel anything with my hand on top of it. 

  I'm stumped.    could there be a latching circuit that holds the relay "on"?? (don't see how it could, as the relay socket only uses 4 of the 5 spades of the relay)  If the pump is not running, does the relay open on purpose?    Heck, I'm not opposed to running a hot (fused) wire back there to run the pump, but there must be a reason for having the relay.

Doesn't the pump have a pressure switch built into it?  Or is there perhaps a seperate pressure switch somewhere in the system?  (don't see any reference to it in the Service Manual)


I hate to put the new pump in if it is not needed.  Guess I'll go back out and cut the wiring to the pump and check continuity thru the motor, to see if it's open.  If it IS open, I'll go ahead and replace pump.

as always, I appreciate any suggestions or insight from the "collective mind" of this website, there sure are some sharp individuals here who are generous with their knowledge, and I'm thankful for that!

Cheers!  (I'll need more than a cold one tonight if I can't figure this out!) 

 

[House Husband]

That small fuel line is for the generator. Not a hack. It was installed by the Coach manufacturer.
The fuel pump will only run for 1 or 2 seconds when you turn the key on. It will run continuously when in the start mode or the engine is running.

Richard

 

[wae]

I hate loading up the parts cannon and laying down suppressing fire, but if you've got the tank out already and there's a shiny new Motorcraft pump in your hand...  I mean, how do you not just go ahead and put that baby into place amiright?  You've done (or have at least committed to) the crappiest 90% of the work, might as well never have to do it again.

That said, the behviour you're seeing is basically normal:  In most EFI systems, the first thing the computer wants to do after it drinks its first cup of steaming hot electrons is to send a priming pulse of fuel to make sure the injectors are all ready to spray.  So when you turn the key and power the system, it will instruct the fuel pump to run for a second or so to bring the fuel lines up to pressure so that when it starts cranking, there's plenty of fuel ready to go.  Also, when the RPM of the engine is below a certain value (and I don't know what that is for this particular system, but 300 RPM is a non-unusual number to expect) the computer will shut off the fuel pump. 

Now that you've got the whole she-bang out of the rig, here's what I would do:  I like to start testing at The Whole System and then work backwards.  Some people prefer to test smaller systems individually and work up.  No wrong way to eat a Reece's here, but I like my way because I'm a stubborn SOB.  After verifying operation of the test equipment, I would connect a test light or (preferably) your multimeter to the wires that go into the fuel pump.  Let's see what we're getting end-to-end.  While watching the meter, turn the ignition switch from OFF to RUN and see what you get.

If the meter shows you 12-point-some-odd good volts for a short period of time and then goes back to zero, then we've got good wiring, good relays, and all that jazz.

If the meter does not give you good voltage (and by "good voltage" I mean equivalent to whatever the battery is giving you), then we have a problem between the computer and the fuel pump so we need to start working that back.

If you do get good voltage, the next thing you want to do is crank the engine while watching your meter.  This one is a bit tricky, though, since I don't know off the top of my head what speed triggers the fuel pump.  But let's see if you get solid voltage while cranking. If you do, then we know the problem is likely not electrical - it's either the pump or something obstructing the fuel between the pump and the intake manifold.  We'll deal with that later, if that's the case.

If you do not get voltage at the pump while cranking, let's get a scan tool of some sort and hook it up.  Now if this is a 1996 chassis, it should have an OBDII connector.  I checked the '96 F53 owner's manual and it indicates that it is an OBDII system.  If you have a 1995 chassis that they built a 1996 Pace Arrow on, you might be out of luck.  Look around under the dash and see if you can find an OBDII connector.  When you do, you'll need a scan tool that can show you live data - a cheap Bluetooth-compatible one from Amazon plus Torque Pro on an Android phone/tablet will get the job done.  You want to watch the engine speed (RPMs) PID in the scan tool while you crank the engine.  If you crank the engine while watching that, you should see a couple hundred RPMs register while the starter is turning. 

If you do not see any RPMs or if the reading is unstable or looks irrational, then the computer doesn't know that the engine is spinning and thus will not turn the fuel pump on.  I think that in 96 they were still using a pickup coil inside the distributor to tell HAL9000 how fast the pod bay doors were opening and closing. 

If you do see RPMs, then we need to check the actual fuel pressure and flow.  The easy test is to pull the fuel line and drop it in a bucket, jump the fuel pump relay and let it go.  You should get a good solid stream of fuel that doesn't sputter or choke after letting it run for several seconds (like 20-30).  I've had some nasty issues that I couldn't find before where fuel pressure was good, wiring was good, but the thing would just cut out with no rhyme or reason.  I'd let the pump run into a bucket and it would push fuel strong for a few seconds then sputter and quit and then start back up again.  So checking fuel pressure is important, but not the whole story!

With good flow rates and no sputtering, then I would hook up the fuel pressure gauge and jump the relay again and make sure you're making good pressure.

If all of that is good, pull your injector connections and hook up some noid lights to verify that the injectors are getting power when you crank.  If the lights are flashing and you've got good fuel flow and pressure, then something isn't right with the injectors.  Pull the injectors out, get a 9-volt battery and some wire, and complete the circuit on the injector to see if you get a good solid click on and off. 

 

[mikeylikesit]

Thank you WAE, I think I owe you a beer or 7.  That gives me a much better understanding of how the system is supposed to work.

After sleeping on it, yes, I'm going to go ahead and install the new pump. Dropping the tank was pretty straightforward, removing (detaching and moving aside) the rear leveling jacks was the real PITA, never want to do that again!

This rig has run like a spinning top for the 3 years or so and over 14K miles that I've owned it......at least the chassis has. Hard to believe that the fuel pump would fail while sitting in my driveway. (thank you lucky stars if that is the case)  Tank always stored full, never run below 1/4 tank.....but stranger things happen, I bet. 

I appreciate your time writing all that! 

 

[wae]

No worries, just remember that free advice is worth every penny you pay for it!

One other thing that I thought of - you could short-circuit the testing process (heh.  get it?) by going to the pump-a-bucket step first.  Put the fuel hose at the engine in a bucket and jumper that fuel pump relay and see if you get a stream of fuel.  Keep the hose in the bucket, put the relay back, and then watch it while you flip the key from OFF to RUN and see if you can watch the priming pulse.  If those two things work, then you know that the wiring is good, the fuse is good, the relay is good, the pump is goodish, the filter is goodish, and the fuel lines are goodish.  If jumping the relay doesn't get you a bucketfull of gas, then you know that regardless of what the computer thinks it's trying to do, the pump's never going to get the message.  Either way, you've quickly cut your failure domain in half.

Just, you know, be careful with all that fuel.  Or at least make sure the insurance is paid up.

 

[House Husband]

Ford did NOT use OBD-II on 460 F53 chassis. The first OBD-II F53 was on model year 1999.
Your OBD-I connector is in the dog house, adjacent to the accelerator pedal. Will probably have a plastic cap on it. EPA required OBD-II connectors to be with in 6" of the steering column.
Do not unhook a fuel line and jump the fuel pump relay. That's just asking for a mess and possible fire.
The fuel pressure test is all that's needed.
When in the start mode, the computer does not look at RPM to keep the fuel pump running.
So much bad information from wae. Tread carefully.

Richard

 

[mikeylikesit]

well, wanted to circle back put this issue to bed.      It was the fuel pump.    my real issue was determining if it was the pump that failed, or the chassis control system that was not telling it to run. 

Once I got the tank dropped and had access to the wiring at the pump connection, (and learned that the PCM gives the pump a 1 second signal, then waits for RPM), I used a matchbook cover to hold the relay contact closed and had good voltage at the pump. (eliminating a bad wire as the culprit)  Then, had the wifey attempt to start......with pump disconnected, and watched the test light.  It lit for 1 second, then, after the motor cranked for a couple of seconds, it came back on steady.  This told me the control system was working correctly, and it had to be the pump.

Got the new one in, tank back in place and refilled, and after cranking just a tad bit longer than normal, she started right up. 

Funny part (if there is one.....dropping the tank is a PITA)....put the old pump on the bench, applied 12 volts, and nothing. smacked it with a SFH (opposite of a BFH) and it started running. HAHA!

one thing I'm still wondering..........inquiring minds and all..........is that if the pump mechanism locked up, why didn't it pop a fuse? anyway, I threw it in the trash on moved on.....


oh, they joys of RV ownership!

Thanks again folks for all the help, it is truly appreciated! 

 

[Lou Schneider]

Might have been poor brush contact to the armature, not that the mechanism locked up.  Congratulations on fixing the problem!