Unexpected engine failure (shut down) 1994 Ford 460 V8

[Geocritter]

This is a question for you folks with older (1994 vintage) Ford 460 V8’s. I had a strange event happen with my rig on my trip from Huachuca City AZ to Fresno CA. I was traveling north on I-5 from LA and just past Bakersfield my engine lost power and shut down. It’s done this once before on a long grade outside of Benson AZ. At the time I replaced the fuel filter and I also back-flushed a bunch of rust from my old filter, so I wrote the event off as a partially clogged fuel filter. This time I’d just gone over 4,148’ Tejon Pass an hour earlier with no problems and I was cruising along nicely on a flat stretch of I-5 with my cruise control set at 60mph when I began losing power. I quickly shut off the cruise control and worked the throttle. The engine started running smoothly again, but almost as quickly began once again to lose power. The engine finally shut down completely and I coasted off the highway. I sat for awhile and tried to start the engine, it barely turned over which was odd because before I’d left AZ I’d installed a brand new group 65 750 amp battery. As a test I beeped the car horn, which draws a surprising amount of amperage, and it beeped loudly. The entire trip my amp gauge was showing it to be charging. Anyhow, after sitting for 20 minutes I gave the engine one last crank and the engine fired up and ran great the last 100 miles to my destination.

So when I started this journey 650 miles before the problem in question I had:

I installed a new group 65 750 amp battery and a new battery cable. Up until this point the engine had cranked strongly. Within the past year I’d replaced the starter.

Within the past 1,500 miles I replaced the spark plugs, air cleaner, changed the oil and filter.

Within the last 650 miles I’d replaced the fuel filter.

The engine typically runs very well, the only consistent problem I’ve noticed is an occasional slight hesitation upon acceleration, and that usually occurs when the engine is cold. It’s such a minor thing that I haven’t given it much thought.

While I’ve owned and driven the machine it’s never over heated, it’s always shown excellent oil pressure, and the amp gauge always shows a slight charge while running (like you’d expect).

I’m a driver who’s normally well aware of what going on with my engine and this engine shut down came with no warning that I was aware of. Does anyone have any ideas what caused my engine to shut down like it did?

Steve

PS I'd suspect vapor lock but (1) I have fuel injection (2) the day before I'd driven under similar conditions through AZ in 100 degree heat.

[Geocritter]

rgatijnet1 wrote:
You may try an external fuel pump but it may not correct, or help with your problem. Dropping the tank to change the internal fuel pump is not a fun job but like many things, there is a right way and a wrong way.
Along with your internal fuel pump you have an internal fuel filter/strainer. Considering the age of your vehicle, it ran for quite a few years with a minimal amount of ethanol blend fuel. The new fuel does a better job of cleaning out your tank, and a lot of that debris is caught in your in tank filter/strainer. This accumulation of crud may restrict your pump inlet from time to time and cause your fuel pump to overheat. Installing an external fuel pump, and using the same fuel lines means that you will be sucking fuel right through what may already be a partially blocked filter/strainer inside the tank. This restriction may actually burn up your new external fuel pump that is not sitting in fuel that has helped to cool the in tank pump.
Just saying if it was as easy as simply installing an external fuel pump, NOBODY would ever replace their in tank fuel pump.

rgatijnet1 I'm concerned about a future clogged in tank screen as well, however I won't be in a position to drop the tank until I get back to Texas, nor will I have the $$$ to have it done for me. Hopefully, it won't misbehave before then. BTW if it does appear to be a future problem I'm now carrying a small nitrogen tank with me to meet my compressed air needs. If it were to become clogged, I should be able to back-flush the screen using a low pressure burst of nitrogen.

[Geocritter]

John&Joey wrote:
You should still clean the ground strap or replace if it's shot, that is what kept your starter from working well.

Clicky

Wow, I just got back from a reconnaissance visit of Kings Canyon and Sequoia NPs using my Dodge Caravan (Soccer Mom-mobile). They sure are beautiful parks! As for the ground strap I replaced it a few days ago running it from a starter attachment bolt directly to the rigs steel frame. It was an instant improvement in my starters performance.

[rgatijnet1]

You may try an external fuel pump but it may not correct, or help with your problem. Dropping the tank to change the internal fuel pump is not a fun job but like many things, there is a right way and a wrong way.
Along with your internal fuel pump you have an internal fuel filter/strainer. Considering the age of your vehicle, it ran for quite a few years with a minimal amount of ethanol blend fuel. The new fuel does a better job of cleaning out your tank, and a lot of that debris is caught in your in tank filter/strainer. This accumulation of crud may restrict your pump inlet from time to time and cause your fuel pump to overheat. Installing an external fuel pump, and using the same fuel lines means that you will be sucking fuel right through what may already be a partially blocked filter/strainer inside the tank. This restriction may actually burn up your new external fuel pump that is not sitting in fuel that has helped to cool the in tank pump.
Just saying if it was as easy as simply installing an external fuel pump, NOBODY would ever replace their in tank fuel pump.

[John_Joey]

You should still clean the ground strap or replace if it's shot, that is what kept your starter from working well.

Clicky

[2bzy2c]

Glad we could help. Please post your results after you make the repairs and let us know if and what helped.

[Geocritter]

I've decided to take Heisenberg’s lead and install a secondary inline backup pump connected to a dash mounted toggle switch. That way if and when the factory pump finally fails I’ll just switch on the backup pump. As far as costs go, by the time I’ve purchased the pump and fittings I might be into it for $100 and maybe an hour of my installation time. Not bad for the redundancy it affords. Who knows, though the engine ran very well going over Tejon Pass it was probably sucking gas to the tune of 2mpg or less, it may be nice having a backup pump running during a similar future situation. Like my late wife used to say “If some is good more is better!”

Along with an answer to my original question, I’ve gotten some wonderful bonus information from this thread. Thanks to comments from PUCampin my starter is finally working great after installing a dedicated engine ground, my alternator seems to be working more efficiently too. Though I didn’t want to spend the money, after ptl_10’s remarks I’ve decided to replace my coil (along with the plug wires, distributer cap and rotor) and maybe it’ll get rid of that slight engine hesitation I’ve been living with and keep it from getting worse in the future.

Man o’ man, you guys ROCK!

Steve

[wilco]

I too suspect the fuel pump. The in-tank pump on that vintage 460 has/had about a 100% failure rate over time. If yours is still the original pump...it's a miracle! Been there, done that on a '95 that failed after about 5 years. You may have other issues but I'd look here first.

[John_Joey]

For your logic to be correct then two things would also be true. The depth of a 80 gallon tank is much greater then a 19 gallon tank. I think what you will find out is it's not the depth but the length and width that will be where the extra fuel is stored in a RV.

Second, all 460's would be having that problem from day one. Mine never did as many others didn't. The fuel pump of that vintage did have a design flaw, but most have been replaced. The new ones have a four wire connector as I remember. If you have the old pump you will need the new connector also.

Yes fuel pumps start to fail when they get hot. This might be your wake up call from a good 'ol girl trying to tell you "best fix me now before I strand you." That pump may be generating more heat due to worn out internal parts, or bad electrical connections.

[Geocritter]

What I’m thinking with these fuel pump problems from that vintage is that they were using fuel pumps that weren’t designed to fit something with the depth of a 75 gallon tank. Instead they installed a standard 19 gallon tank fuel pump and used an extension hose on the inlet to reach the bottom of the tank. Under that scenario the fuel pump motor, which is designed to be submerged for cooling, would soon be high and dry when half the fuel in the 75 gallon tank was used up, causing the pump to run too hot and automatically shut down until it cooled off again.

Am I missing something here?

Steve

[Heisenberg]

I had some thermoplastic hose prior to the fuel filter and for me that was the easiest place to cut in. Right off of the top I cannot think of any reason to go post filter.

[Geocritter]

Heisenberg, I read the reviews and they were all excellent. However, one reviewer said he swapped locations with the fuel filter. Here's what he said:

It did require changing the configuration around. I had to swap the Fuel Filter and Fuel Pump locations. The pump works great.

Do you have any idea why he did that?

Steve

PS thanks for the link, I've saved it in my frequent places links for future reference.

[Heisenberg]

Geocritter this is the one I used.

[Geocritter]

John&Joey, The rig spent most of its life in up state New York and does have a lot of rust (I'm sure having an aluminum body shell on top didn't help much either). It might not be a bad idea to check out the fuel pump ground. I know my fuel gauge is very erratic to the point where all I keep track of is miles between fill-ups and have given up even looking at the fuel gauge.

ptl_10, I replaced the plugs not long ago, based on that little hesitation my engine has, new plug wires and a new coil might not be a bad idea!

Steve

[John_Joey]

As I remember you should have a grounding wire on that fuel pump. Might want to make sure that ground is corrosion free also.