1993 Ford 460 engine problem

[Woody Harris]

Hello everyone. I have a problem with my 1993 Ford 460 engine that all of sudden will not start. I have replaced wires,solenoid,starter and it now cranks but starter does seem to not give enoungh power to start. Replaced spark plugs New battery. Any suggestions

[fletch460]

Woody, I have a 95-460. Sometimes I have to use the Boost switch on the dash to get it started if my chassis battery is low. If it dont spin fast then I would ssuspect a bad ground somewhere. After trying to start, see if the Pos terminal on batt is hot. If so I would check grounds.

[blackf3504dr]

Fuel pump ? Have you checked the engine to frame ground ?

[IC2]

As noted above, the ground is usually the first problem with slow cranking. Next would be the actual power lead to the top of the starter mounted solenoid (or even the starter if it's a reman). Manufacturers do NOT use optimum cabling, only the absolute minimum to get that power from the battery to the starter. It becomes even worse if the battery has been moved by the coach builder and what he has done is only lengthened the existing cable with a stand off post. It probably has the original Ford AWG 4 cable when it needs a awg'0'. That post, if that's the way it was done, may have some corrosion or is loose

[morefun]

I am having the same problem with my 1993 Ford 460. It will crank for maybe 10 seconds before it stumbles to life. After that it runs fine. The Boost button helps it turn over faster so it may help reduce the cranking time. I have tried turning the key on and leaving it for 5-10 seconds before trying to start it, but that doesn't seem to help. I think you are right that cranking then stopping a few times does seem to get it going.

Before this problem started, I had another probably related one. The engine wouldn't crank (unless I used the Boost switch). It took several days of starting with the boost button before I found a solution (I replaced the positive battery cable - the posts were clean but the cable was open). The long cranking problem started during this time when I was using the Boost switch. Is there a connection - I don't know.

Want to add another problem that showed up at the same time? My RV coach generator starts and runs fine but I get no (or very little) power out of it.

All of these sound like ground problems of one sort or the another, but I haven't figured out where to start checking. I'd rather not drop the 70 gal fuel tank if I can help it.

[Mekanic]

To run at all you need both fuel and spark.
To run properly with full power you also need compression as well and your spark at the right time.
The quickest was to test for fuel is to spray some starting fluid in it and see if it will run, if it will start and run only when spraying the fluid you have no gasoline getting to the engine.

[subford]

morefun,

Why would you leave the key on 5-10 seconds before trying to start it?
I can not think of anything that would help in trying to start it.

If you turn the key on (for one second) and off about four times you can fill the fuel lines with fuel if you have a bad check valve in the pump that let them drain dry.

[morefun]

I tried leaving it on with the theory that it might take a second or two to pressurize the lines. I've heard the suggestion of turning it on and off a few times, but I wasn't sure why that would help or be different from leaving it on for several seconds.

[subford]

morefun,

Each time you turn on the key the computer will run the fuel pump for one second and then turn it off. You have to do it more than once if the fuel lines do not have any fuel in them before you will get the pressure up to 30-38PSI to start the engine.
You will not get any pressure by just turning it on and leaving it on if the fuel system is dry with your long fuel lines.

The fuel pump does run again for one second when the computer sees each PIP pulse from the distributor while the engine is cranking or running. Then if the engine dies (key on) the fuel pump will run for one second and then quit running.

Idle fuel pressure is from 30-34PSI and at 40PSI at Wide Open Throttle. The engine will not run below 28PSI.

PIP pulses come faster than one second at cranking or if the engine is running so the pump will run all the time the engine is cranking or running.

[morefun]

Wow - very knowledgeable and well explained answer! Thanks.


My problem seems to be related to how long the engine has been off. It is inconsistent, but generally it starts easily if the engine was just turned off, but may need cranking if it has been off for for as little as 10 minutes. It seems like your suggestion of turning the key on for a second then off several times before starting does overcome the problem.


From what I read in this good "Troubleshooting Electronic Fuel Injection Problems" article (http://www.aa1car.com/library/2003/us60324.htm), it sounds like my system isn't holding its residual pressure after the key is turned off. They suggest it could be a leaky fuel line, a leaky fuel pump check valve, a leaky pressure regulator or one or more leaky fuel injectors. I don't know if any of these relate specifically to the Ford 460, but with no obvious signs of leaks, I'll probably have to take it to a dealer to pressure test and diagnose the actual problem.

[subford]

All of the items you named above could cause this problem of not holding of its residual pressure after the key is turned off.

If you can get a dealer to work on this problem you are talking a lot of money.

I would doubt the fuel injectors or the fuel pressure regulator as most of the time the F53 does not usually have a high mileage engine and those parts happen most of the time with high mileage. Fuel lines would be very obvious. A bad fuel pressure regulator would also have to have a bad shuttle valve in the fuel delivery module also for this to happen.

That leave the high pressure check valve in the fuel delivery module. Not an easy job to change the fuel delivery module. The easiest way if you do not have a water tank above the fuel tank is to cut a hole in the floor of the motor home. Other than that it means dropping the fuel tank to change it out.

Your fuel system:


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[blackf3504dr]

I had the same problem and it turned out to be the check valve. I cut an access "door" in the floor to get at the fuel pump (fuel delivery module), measured more then twice, peeled back the carpet and cut the opening.
The rest was a piece of cake. Ours is a 91' chassis and the connectors on the fuel lines could be released with a flat blade screwdriver but I know that later chassis require a special tool to release them. Bill (subford) was very helpful to me when I did ours and knows what he's talking about.

[Woody Harris]

Originally Posted by Woody Harris

Hello everyone. I have a problem with my 1993 Ford 460 engine that all of sudden will not start. I have replaced wires,solenoid,starter and it now cranks but starter does seem to not give enoungh power to start. Replaced spark plugs New battery. Any suggestions

So all suggestions have been help full, however I still have the problem. I am going to bleed pressure from fuel (if I can fill the valve to do so) and replace the fuel filter and use some starting fulid. Anything to get my wife off my back (lol). hope it works

[subford]

Woody Harris,

The below is if it is cranking OK.
Before changing the fuel filter (not likely the problem of a sudden no start) and bleeding the fuel system (this would not help, it will bleed itself).
You need to find out what the problem is.
A fuel pressure gauge and a set of NOID lights will more than likely get you going.

First of course check to see if you have any codes. Get a clip board, paper and pen. Just ground the STI wire, set behind the wheel and turn on the key and watch the MIL in the cluster. Count the flashes of the MIL and write the number of flashes down.
Post the number of flashes here and we will help you with them or if you get the OK codes (11 or 111) go on to the next step.

Put a NOID light on any injector plug and crank the engine, if it flashes put the fuel gauge on the test point. If not check for power on the red wire with a test light with the key on.

Hook the fuel gauge to the test point on the fuel rail. Ground the fuel pump relay wire at the EEC self test connector and turn on the key. You shoul get 40 to 45PSI reading.
Let us know what you find and we will try to help you some more.



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