i have a 460 in a e350 1990, its on a triple E rv. the problem is that it seems to hesistate and not have its normal power after the engine warms up. You can take it for a drive and it will work good, but after a couple miles it starts to hesitate when you try and accelerate and it won't go over 30mph. I changed the fuel pump in the tank, and put new spark plugs in it. Any ideas what i should try next?? i also changed the fuel filter, it looks like there is another type of pump mounted by the fuel filter on the frame rail...what is that for??
TIA

 

You took the post right out of my mouth....
i have a 1995 econoline shuttle bus... its has a ford 460 in it and I have the same issue... it runs good for a while as it heats up it gets worse begins missing and losing power. I drove it ten minutes once (up to 40-50mpg) and then encountered several large inclines where the bus barely made it up it (5mph) when I got up the hills and on flat ground it still ran poorly. I parked it on a side street thinking of having it towed for a few mins. Got in it started it and it had power and acceleration again. ! !

I too changed the air filter, plugs, wires, checked the dist. cap and nothing is working !

Lets get this solved !

 

that piece your talking about is the secondary fuel pump. I was told by a very experienced mechanic that he thought the problem would be this secondary fuel pump. Where is it located I couldn't find it. I think im going to change this and hopefully it fixes my problem

 

It is located on the driver's side inside frame rail just about under the driver's feet.
The pump(s) in the tank(s) are low pressure pumps the one on the frame rail is the high pressure pump.

 

do you think this is the issue were experiencing ? where could i buy one of these pumps for replacement from?

 

Most auto supply stores may have one or could get you one, but Ford dealer is a better choice.

 

So mine is the cat converter, i opened up 2 holes into it and took out all the honeycomb stuff so its empty now, runs like a dream just like new yeah

 

i have 1993 ford motorhome e350 and 460 engine with same problem, runs good for awhile then becomes flat on acceleration. what was the diagnoses of your problem?