Runs, and stalls...and runs, and stalls......

I agree with the oil pressure switch.. That was a problem on my original towed.

Yes, I replaced the oil switch and still no go.  I will try to wire the fuel pump up directly to see what happens.  No idea where the relay may be.......

Need a new carb or real good rebuild. they have some small passages that get gummed up from sitting. and my last bad carb ran just like you are describing. i must have rebuilt mine about three times because i know how to do it and it still beat me. I kicked myself in the arsse because it took me 10 minutes to install the new one that runs like new now.
Too ever avoid that from happening to mine i installed a fuel shut off before the carb and when i am going to store it I run the gen with the valve closed till it starves it self and shuts off- meaning no more gas in it to gum up and ruin my next trip. that was a 5 dollar valve thats priceless.

Some ideas that haven't been suggested:

Clogged (I.e. Dead) catalytic converter.  (Happened to me 3 times)

Reset fuel pump switch in right passenger footwell (if I remember right)

Does a 90 have an in tank pump and filter?  If so check it too. (Big PITA to do)

Mine had multiple filters.  One IN the tank, another on the DS frame rail under the driver.

It does sound like a clogged something.......  Inside the carb or elsewhere.  I got tank of gas in Colorado that had a bunch of rust in it.  It did the same thing.  Without the pump pushing it the flakes fell off and would allow some fuel through but as soon as the flow got going it clogged up again and stalled.

Good luck!

73 MAKO look for the collision module and reset it. Not sure where it is on a MH. On cars it was in the trunk, On Vans it was in the right kick panel. Good Luck.

In the front passenger seat, look under the dash on the firewall or sidewall for a fuel cutoff switch.  Could of been activated by a wayward foot, or while it sat someone backed into the MH and activated the switch...

and the search continues....
There is not something clogged. and its not the impact sensor.  It does not need a carb as it runs great while its running.
Yesterday, we rigged up the fuel pump to an external battery.  with it running all the time it floods the carb out, but if I attach it for a bit, then disconnect it, the rv continues to run.  Here is the catch, even with the fuel regulator dialed all the way out, it still floods.
Also, I have no power in the dashboard.  No hazards, no lights, nothing. But it will start and run.....for a minute and a half, two min.
I cannot find a mobile tech who does electric work anywhere.....

The ignition switch, in the start position,  supplies power to different circuits.
When it is returned to the run position it powers all the systems you always see
when it is running. You mentioned no dash power, that may be related to the problem
you are having.  When you replaced the ignition switch, did it include a pin-out
schematic for the wiring?  If not, you can try an OHM meter to determine the circuit.
If you find that the run position get it's power from a specific pin , you have to check that the ignition
switch plug has power to that pin.  There may be a separate fused power supply for the run operation.  Using a power tester (test light, buzzer, DVOM) check both sides of all fuses.  Are there any fusible links? 
The flooding carb was probably caused by a higher pressure fuel pump than the vehicle calls for. 

Be very careful when putting those fuel lines back on.  Usually, when you see a car on fire on the highway, it has had recent fuel line work.  Loose connections + hot engine = FIRE!

73mako said:

Yesterday, we rigged up the fuel pump to an external battery.  with it running all the time it floods the carb out, but if I attach it for a bit, then disconnect it, the rv continues to run.  Here is the catch, even with the fuel regulator dialed all the way out, it still floods.

Click to expand...

I have never heard of a fuel pump that needed to be keyed on and off, all of them are designed to pump up to a specific pressure and stop till the pressure goes down.....  That said.

I HAVE seen a needle valve on a carb get fouled and fail to close, thus allowing too much fuel into the bowl and flooding the engine.. That I have seen on two different vehicles several times.

ALSO, on both vehicles I ended up replacing the fuel pump shortly after.

The problem was a diaphram in the fuel pump flaking off and the flakes clogging or rather blocking the closure of the valve.

73mako said:

and the search continues....
There is not something clogged. and its not the impact sensor.  It does not need a carb as it runs great while its running.
Yesterday, we rigged up the fuel pump to an external battery.  with it running all the time it floods the carb out, but if I attach it for a bit, then disconnect it, the rv continues to run.  Here is the catch, even with the fuel regulator dialed all the way out, it still floods.
Also, I have no power in the dashboard.  No hazards, no lights, nothing. But it will start and run.....for a minute and a half, two min.
I cannot find a mobile tech who does electric work anywhere.....

Click to expand...

I believe this is the first time you mentioned no power at the dashboard. Did this just happen or has this been a problem the whole time? Depending on how your vehicle is wired this could be one of your problems. On our Luxor the dash looses power occasionally because of a relay that is sitting in a socket with loose connections. I tap the relay and it comes back to life, no way of telling if yours is wired the same way. One problem at a time.

The carb flooding could be a couple of things. 1. trash under the needle valve in the carb, 2.    Float has saturated or has a hole in it 3. fuel pressure too high.

Trash under the float is very possible since you have disturbed the fuel lines and is an easy fix but the carb has to come apart. Early carb floats may or may not be resistant to todays ethanol. Your fuel regulator may be bad or if your fuel pump is a rotor type by carter, like the one below it has an internal regulator that will stick shut due to corrosion from ethanol. ( I know this because it has happened to me several times).

So far you have eliminated a host of possibilities. Do you feel comfy taking the carb off and dissembling it? Can you get a fuel gauge stuck in the fuel line anywhere, like with a tee or an adapter inserted in the line for gauge?

If I had to bet on any one thing it would be a carb rebuild, she has sit for a long time and unless the carb was run dry before storing it there is gunk in the passages and float bowl. Depending on what model you have some are easier than others to take apart. Holleys are the easiest, then edelbrocks and last quadrajets are the most difficult.

This is a long shot, but it sounds just like the behavior due to a blocked fuel tank vent back in the pre-emission days. Same thing would happen if you replaced a vented fuel tank cap with one that wasn't vented back then.
I know that today's fuel tanks aren't vented to the atmosphere, but they still must have some mechanism to prevent a vacuum from forming in the tank as fuel is pumped out of the tank to the engine.

1990 ford 460 in an f53 chassis does not come with a carb. It is throttle body injected (TBI). Stop throwing parts at it and ID what you have. Buy a repair manual that covers 1990 Ford 1 ton van with 460/7.5 drive train. Drive train will be virtually identical. It will be OBD 1 the manual will show you how to scan the codes with a paper clip. I fear you may have complicated things by throwing parts at it.

Bill

John, the fuel pump for fuel injected vehicles are positive displacement
pumps.  They will pump fuel at long as they have power, with pressure limited
only by the fuel pressure regulator, or in the case of a restricted fuel line
by the pressure relief valve in the pump. The diaphram you mention is part
of the older mechanical fuel pump, the pressure is regulated by the design
of the pump.

There is a pressure regulator in the throttle body. TBI only uses 10-15 PSI, excess fuel goes back to tank.

Bill

Mistere.. Understood,  Driftless. He mentioned a carb, not a TBFI..

In either case... The problem is in the fuel flow regulator,, Be it a needle valve, or a pressure regulator it is not either stopping the flow of fuel or returning it to the fuel tank as happens on my Workhorse,,, it is flooding the engine.

Problem I am familure with. for reasons posted above.

Without more information such as fuel pressure I think we are running in circles but if I was a betting man, I believe Catblaster gave you the answer that a carb rebuild may be in order.

driftless shifter said:

1990 ford 460 in an f53 chassis does not come with a carb. It is throttle body injected (TBI). Stop throwing parts at it and ID what you have. Buy a repair manual that covers 1990 Ford 1 ton van with 460/7.5 drive train. Drive train will be virtually identical. It will be OBD 1 the manual will show you how to scan the codes with a paper clip. I fear you may have complicated things by throwing parts at it.

Bill

Click to expand...

You are right of course Bill, if it is 1990 f53 it has to be throttle body, there was some mention of an oskosh chassis having a carb. The best way is for 73mako to post us a couple of pictures of this mysterious throttle body carb.....how about it Mako??

Not sure when Ford went to TBI but remember on RV's that the chassis could be a model year older than the titled RV depending on when it was built.