Ford Econoline Engine burps, (94 Ford 460)

Ok, I have to admit I didn't do proper periodic maintenance on this motor home conversion. That being said.I started having the engine getting a "hitch in it's getalong" if you know what I mean.

Several times a minute after starting and usually a lower speeds, she 'stumbles' for a split second and then runs normal for a while. Very random and very annoying.

Here is what I have done so far:
1. Replaced the fuel filter (and it WAS a mess w/dirt and rust inside). Although I didn't drain the fuel tank, I did cycle the fuel pump 4 or 5 times to pump fuel thru the line and out into a bucket.

2. Replaced all 8 sparkplugs (very badly eroded eletrodes but light brown residue on all). Also replaced all plug wires (whoever designed the access on this beast ought to be shot. Took me 6 hours and chewed up both hands to do plugs and wires!).\

3. Replaced the coil

4. Checked the air filter

5 replaced a bad looking vacuum hose and a breather type hose that fell of the air filter.

6. Used lots of "Sea Foam" and a couple of bottles of 'heat'. Ran a tank and a half of gas thru with them in it.

7. Replaced the distributor cap and the rotor.

8. Just now decided to drain some of the fuel and it had noticable rust/dirt in it. Probably out to change the fuel filter again huh?

NONE of these things made a difference. Engine STILL runs rough (no let me say BURPS or twitches at least once or twice a minute) below 45 or so miles and hour. However, while cruising along at 55 mph it seems to be ok or barely noticable at the higher rpms.

Would a bad or clogged fuel injector do this? I have never messed with injectors before. Vehicle has 73K miles on it. And other than changing the oil and replacing an exhaust manifold to pass inspection, I haven't had any trouble (and, didn't do any other regular mainenance). There is no check engine light showing.

Thanks for your help.
Do you
have the same problem?
Monday, April 23rd, 2007 AT 2:06 PM

1 Reply

Stumbles are usually the result of motor problems.
If the compression is good, this is no indication
of motor health.
What does the vacuum guage do when the stumble happens?
Interpreting vacuum is important.
I had a 300-6 engine that was sabotaged.
Although it was discoverd to have 3 cracked piston skirts, and loose valves etc, the compression was @ 120 on each cyl.
This motor had an annoying stumble as well.
If you have the pedestal rocker arms you might try adjusting the valve geometry.
Clearance 'is' critical, especially with a geared cam.
If the valves are set improperly at the factory, the guides will become hourglass shaped, and this lowers compression and makes rattling noises going uphill.
When the valve geometry is correct the engine only needs 87 oct, and you get no uphill noises.
The 460 should be a great motor, and if the valve geometry is 'exact' no valve adjustmens should be needed for > 100 000 mi.
Take the time for all the basic readings; compression, vacuum, battery voltage, proper alternator belt tension, good marine battery cables. Etc.
A loose alternator belt may discharge the battery somewhat and the ignition pulses won't be strong.
And this could carbon your distributor rotor/cap contacts.
Check to see if the distributor is slipping in the engine block.
I had this problem, and the gas mileage goes down considerably.
Anyway, the purpose of the forum is to attempt to help people.
Realistically, engines are simple contrivances, and when you build your own motor carefully with fresh parts, you will be most satisfied.
Onward Christian 460's !
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Monday, July 30th, 2007 AT 1:39 PM

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