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Skygeezer · 05-22-2016, 03:36 PM

Hi to the group. We own a 1990 Rexhall motor home with a Ford EFI 460 engine. It has run like a top for years. Last fall it began to backfire like crazy when you took your foot off the pedal. Fuel mileage went in the toilet, it was pouring fuel through the engine. I suspected water in the fuel since the generator, which feeds from the main gas tank, wouldn't start. A mechanic worked on the vacuum system which was leaking and we added all kinds of fuel conditioner to eat water. Barely got home and parked it for the winter. This spring I took it in for an ignition tune which did nothing. It died 3 times on the way home, finally rolling into the yard and dying again. I would suspect the famous Ford fuel pump problem but why is it flooding the engine with fuel? Must be a sensor or computer issue. Any ideas where I can start? Local mechanics are helpless if the computer can't tell them what to do. Ford dealer won't look at me because it is a motorhome.

LJowdy · 05-22-2016, 04:41 PM

I could be wrong but if the fuel pressure regulator isn't working that will allow the system to over pressurize. Another problem could be injectors stuck in the open position.

twinboat · 05-22-2016, 06:37 PM

Do you still have the bad watery gas, now full of conditioners that don't eat water in the tank ?

Read up on phase separation of E gas.

All of that junk is sitting on the bottom of your tank.

My advice would be to get a hose to the bottom of the tank and suck some out. You could also bleed some from the fuel pressure port.

Pour it in a glass jar and let it sit. See if it looks like unmixed salad dressing.

Now you will know.

Skygeezer · 05-22-2016, 06:41 PM

It's mostly Sea Foam in there now. And of course the tank is full of fresh gas. Have to figure out how to drain some. There were no conditioners in the tank when it was acting up and backfiring last fall.

House Husband · 05-22-2016, 07:57 PM

Pull the hose off the fuel pressure regulator and see if it is wet inside. Could be a ruptured diaphragm.
Why do you believe it's pouring fuel through the engine? Black smoke out the tail pipe?
Because your engine dying problem, I would suspect an ignition problem. Take the ign. module, located on the fire wall, out side, in front of the driver, to a parts house and have it tested.

Richard

bcbrowne · 05-22-2016, 08:08 PM

Check your fuel filter, had a 454 in a holiday rambler years ago and had similar issues, always changed fuel filter with regular service, on the way back from a 500 mile trip started backfiring some and dying, found out it had a second fuel filter along the frame rail that was original, about 15 years old, replaced ot and ran great again

cb1000rider · 05-22-2016, 08:11 PM

1990 had 02 sensors? Run the diagnostic?
IF it's backfiring under no-throttle, I'm expecting closed loop to be off.. (Note, this is from experience with EEC-IV, not trucks, so not sure if it's the same)

Skygeezer · 05-23-2016, 05:58 AM

Quote:

Originally Posted by RLS7201

Pull the hose off the fuel pressure regulator and see if it is wet inside. Could be a ruptured diaphragm.
Why do you believe it's pouring fuel through the engine? Black smoke out the tail pipe?
Because your engine dying problem, I would suspect an ignition problem. Take the ign. module, located on the fire wall, out side, in front of the driver, to a parts house and have it tested.

Richard

The fuel is going somewhere. It is using 2-3X more gas than normal. Black smoke on the backfires. Old plugs were burned black. Acts like it is running extremely rich. I'll see if I can find the ignition module.