Hi,
I am new to the Ford big blocks and trying to troubleshoot and old motorhome I bought.
It's a 1987 ford 460 from and E350 chassis.
Moto was running fine and steady.
Before a huge trip I wanted to clean things up so I cleaned the carb with sea foam and put carb cleaner in the fuel tank.
I drove for about 3 hours with no issue and parked the motorhome in the driveway, nose up on a very slight slope (4-5 degrees)

After 2 weeks, I tried starting the motor and had a very very hard time starting it. After 10 minutes or so, I finally go it running. but it died after 30-40 seconds.
I can start it back with pedal pumping, but it always dies out. A lot quicker if I give it gas.

I thought it was a fuel problem because of the carb cleaner in the tank so I replaced the fuel filter to no avail.

Still the same behavior :-(
I am a bit desperate as I'm to leave on my trip in 8 days.

I discussed with another member here who suggested to post here looking for "subford" and told be about a "hot fuel handling" system which could also be problematic?

My father suggested these older motors had multiple fuel filters and although I replaced the inline filter below the frame, there could be one behind the carburetor which I should also replace?

Thanks in advance for all your help

Phil :-(

 

Pull the doghouse and jump the oil pressure switch on top of the engine at the very back.
See if it will run then.
There may be a screw in fuel filter where the fuel line enters the Carb.

The "hot fuel handling" system is just a sized orifice with a return line to the fuel tank.
This keeps fuel moving in the fuel lines to prevent vapor locking. But vapor locking does not sound like your problem.
Do you have one or two fuel tanks?

Your fuel wiring should be something like the below diagram if you have one fuel tank:



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Thanks for all the info.
There is only one fuel tank on the motorhome.

I have the kids tonight so I'll check that after the office tomorrow!!

Thanks a bunch!!

Phil

 

Also check fuse #3 as it could be bad also check the fuel shutoff Inertia switch as it could be open.

If the fuel system checks out you could have a problem with the ICM or PIP sensor.

 

Well...
Was not able to start the motor last night as the battery was too low.. so I plugged the charger on it.
I did notice the fuel line is a hard line going to the "hot fuel bypass orifice device" and then the 2 hard lines are going done the engine somewhere close to the oil filter where I could see because of the fading sunlight.
Does that mean I have a mechanical fuel pump?
Ground was too wet from pouring rain to lay down and verify lines going to the fuel tank, I'll check that tonight.
Thanks again guys, I really do appreciate the help.
Phil

 

No you do not have a mechanical fuel pump.

With only one tank you will not have the fuel selector valve or the other tank in the diagram below but the rest is what you have:


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A bit more info (couldn't do much, had to manually push the camper back in the drive way as city doesn't allow motorhome in the street).
I indeed followed the lines and they go straight back to the fuel tank so electric pump indeed.
I disconnected the hard line from the vapour separator and with the ignition on, nothing flows. When starting, I got about 150ml in 15 seconds which gives about 110gph which is the normal pump flow.
I got to unscrew the carburetor filter cylindre and to my surprise, no brass filter in it.
Didn't have time to redo the crank test on carburetor side of the vapor lock valve.

I didn't find the inertia switch behind the pedals on the driver side. looks like the wiring are all redone and I have found a connector with a loop in it.. perhaps it's that one?


hopefully tomorrow I'll have more time to take the doghouse out and bypass the oil pressure filter switch.

I also validated that the choke flap can move easily.

I double checked the fuse and #3 is okay and the solenoid for fuel tank fuse is not there as there is only one tank I presume.

Thanks again for the help, I feel totally like a newbie on truck mechanics even if I did lots of rallye cars :-(

Phil

 

The inertia switch may be behind the passenger kick panel.
The connector with a loop in it may be a two tank jumper for the two tank switch.


That oil pressure switch is not at the oil filter location. The oil pressure switch is on top of the engine at the very back of the engine.
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All right, here's where I am at:
found inertia switch on passenger kick panel, all in order, 12V on both sides, so the switch is ok
found the oil pressure switch like you mentioned, passenger side at the back of the motor and bypassed it.
hmm still no fuel pumping after start.... but the pump does pumps when cranking

I finally found the fuel pump relay on the driver side in front of the house battery and checked the lines
12V on the oil pressure switch side
12V on the inertia switch side but the relay didn't seem to click. since I was alone, decided to bypass the relay and would you look at that, motor not only starts but keeps running....

Is it better to replace the relay or simply bypass it?

Thanks

Phil

 

Replace it.
If you bypass it the fuel pumps will run with the engine off until the battery is dead.

Note the fuel pump should run with the engine not running with the key on as long as the oil pressure switch is bypassed for trouble shooting.

 

Would you happen to have the part number? My local ford dealer says ford doesn't supply them no more and gave me this part number: f19z9345a

Thanks a million for all the help!

 

I would replace it with a newer stile relay like the 92+ ford trucks use.

Use a socket something like this:
NTE Electronics, Inc. - R95-188 - 6.5in wire leads Relay; 5-Pin automotive for R51series (except 70A) Socket - Allied Electronics

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Bill,
I can't thank You enough for everything you've done for me this week :-)
I bought a relay from Napa (AR240), plugged it back and voilà!!!!
That old baby is purring like it should :-)
Thanks again!!!!
Happy Phil