Having what we believe is fuel issues. Does anybody know what the fuel pressure is suppose to be. THe previous owner wired the external Pump direct to the accessory on the fuse box 12v. is this correct voltage? our pressure is about 85 psi. That has to be high! Any ideas?

Thanks Dan

 

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What year is your beast? Izzat fuel injecticated or carborundumated?

I can believe 85 psi for fuel injection, but no way for a carbureted engine.

 

About 35-45 psi for your 1990.

 

On a fuel injecter vehicle (I have a 1992 E-350), the pressure should be between 32-45 psi. Are you getting your reading from the test port on the fuel rail? If you connect the fuel line directly to the pressure regulator without a tee, then 85 psi is pretty good, but the regulated pressure should be muc much lower.

 

I'm having the same exact problem with my '84 Motorhome.I have learned that there are a few parts you should check that are unique to some engines with electric fuel pumps in the 80's.The one is a fuel separator, it is a tee in the fuel line just before the carb, it restricts the fuel pressure down to 5 to 6 lbs pressure it should not go bad but if it does you should know there are three different sizes and unless you can find one at a junk yard you'll need to buy it from Ford.Running the fuel pump direct will allow to much gas to the carb so you ned to use it.Also check the fuel pump relay mounted on the left side near the fender.

 

> The previous owner wired the external Pump direct to the accessory on the
> fuse box 12v

Extremely dangerous thing to do, rewire it so goes to the safety cut off switch and works through the relay. I would guess the relay was bad.

My book shows battery voltage (12+) from the fuel pump relay and spec. is 30-45 psi.

 

OK you got me, tell me more about this "fuel separator" that reduces fuel pressure. I do not think I have one on my 82 E350 460 and could not find one in my micro-fiche for the 80-89 Fords. Got a part number?

 

I'm not sure if an '82 has one or not, I know my '84 and a friends '86 both have them. Many people mistake them for a filter.It is a tee in the fuel line maybe a foot in front of the carb.The way it works is fuel comes in to it from the pump,the separator reduces the fuel pressure to the carb and what the carb doesn't use goes out the tee to the fuel tank.They come in three different sizes,which they measure the diamater of the return orfice the sizes are 0.40,0.60 and 0.90 The original part is color coded if your lucky enough to still have the paint on it.I believe the part probably can be just cleaned out with carb spray,theyre are no moving parts in it.Don't be an idiot like myself and stick a nail down in it and smack it with a hammer to try to free it up.lol The part I bought and I'm not sure if it's the right one(because I beat it with a hammer)was the 0.40 and the part # for that was E3TZ 9N176 B .I bought the smallest hole size thinking I can always make it bigger if need be, but after looking at it I'm not really sure if I can without ruining it? Not all Ford dealers could find it so you may have to shop around.

 

OK I found it, it is called a hot fuel bypass.

The hot fuel system provides for some of the fuel in the supply line to be returned to the fuel tank and thus keeping it cooler and reducing the chance of vapor lock.

The FORD microfiche says:
Name: Valve ASSY. (Fuel Vapor Separator & Fuel Shutoff).

E0TZ9N176-B .090 Used as a field fix for units experiencing hot fuel problems.
E3TZ9N176-A Red Dot .060 For Fuel Starvation or Power Loss.
E3TZ9N176-B Blue Dot .040 For Fuel Starvation or Power Loss.

It also said used only with an Electric in tank fuel pump on 460’s

Thanks for the information, I could not have found it without the part number, I did see it on the microfiche but did not know that was what you were talking about.

I do not think it regulates fuel Pressure, just the amount it sends back to the tank.

 

If you had the part in your hand and blew into the end of it, you would see it controls the pressure and that goes for both separators I have,the 0.40 and the old one which is now a 3/32" hole lol (after smacking it with a hammer and nail)

 

I run Electric fuel pumps to the carburetor without a vapor separator and without any problems, the in tank pumps only put out 4 to 5 Lbs.
I had a fuel problem with fuel starvation and no power but I fixed it with a bigger four-pass radiator.

My RV lived in Ford Shops until I got it and they all keep replacing the Fuel Pump and removing the Gas Tanks and putting them back on. At least this is what all the previous owners said as I call about three of them. And it had very low mileage as a result.

If you have a problem with this thing I think you need one with a bigger hole to allow more vapor back to the tank or run it strait to the carburetor with a bigger radiator.

Can you post a photo of one of these, I have read a lot about them but have yet to see a photo or a diagram of the inside.

 

Thanks for the advice.I have tried running it with both of them and they both do the same thing,the carb primary float runs out of gas in the driveway before I can move it. If I run the fuel pump direct (bypass the relay,ect.) it floods both floats out with either separator.I think the fuel pump puts out more than 4 or 5 lbs pressure(hence the reason for the restricter on an '84),I don't have a pressure gauge so I don't really know?Sorry I don't have a camera that I can take a picture of the part and post it right away,it may be a couple of weeks when I get through taking pictures of my son's go kart he's working on.The tee itself has a bb that the gas needs to go through to get to the carb which restricts the flow and that (the bb)is after the return port.If you blew into the tee very little air comes out the carb side even if you hold your finger over the return port. How does a bigger radiator help?I'm going through the system again tomorrow and if I can't figure it out am probably going to put a mechanical fuel pump on it.

 

Ford sold my RV as they did most as an incomplete vehicle to the RV Mfg. without A/C so Ford put a Three Pass Radiator in it for a 460 with out A/C.
Then the Mfg. put A/C on it and did not change the Radiator that made it run hotter and that extra heat was enough to Vapor Lock it at higher elevations on hotter days. The Four Pass Radiator seems have fixed this vapor-locking problem when nothing else did.

I was wondering if a previous owner put the wrong fuel pump in your RV. It would have to put out FI pressure (45 psi +) to open the float valves and flood the engine. Do not think the Vapor separator was ever meant to reduce fuel pressure as I have searched and searched and found nothing on it reducing pressure.

 

I'm thinking the same thing about the wrong fuel pump.He took the old one out and took it to NAPA and they gave him a new one,so I had to assume it was the correct part.I'm buying a fuel pressure gauge today and will let you know what hapens.I will also post those pics as soon as I can.You've been a tremendous help.Thank You!