F53 460 Engine runs very poorly when heat soaked

[pilotanpia]

My 1995 F53, 460cid runs poorly after being heat soaked.
When engine is cold it runs like gang busters. After a fuel stop and the engine has soaked up the heat due to no airflow through the engine compartment, there is virtually no power at full throttle. Once above 3000 rpm it starts to get power but misses and hesitates. Once up to highway speeds the engine smooths out and runs fine.
I bought the unit with 60,000 miles on it, 6 years ago.
I have replaced the following: fuel pump, spark plugs, ignition module, both coolant temp senders, IAT sender, water pump, radiator, timing cover, thermostat and all related coolant hoses.
I replaced the fuel pump in 2017 because it would only go 35 mph. I was able to hobble it home and make the repair. It was a very easy task, once the fuel was off-loaded. The fuel pump solved the main issue and it runs well until I let it sit for 30-40 minutes during refuelling. One other note, it tends to do better in cooler climates. Not much problem at all in winter months, here in North Idaho.
Most recently, we were coming home from California and our road has one portion about 3/4 mile that is about 7-8% uphill. I could not get past 5 mph using full throttle. It usually pulls the hill at 20-25 mph.
If anyone has any ideas, I would appreciate it.

[Gdetrailer]

RLS7201 wrote:

Gdetrailer wrote:

pilotanpia wrote:

MT BOB wrote:
Lots of F53-460 fuel pump problems, and threads,on the net.
2 things you can try,cheap and easy,replace the TFI and the fuel pump relay.
Other things to try- at your risk- when it acts up,1-loosen or remove the fuel cap
2- when it acts up, throw trans in neutral, turn off and restart engine.

I tried the TFI aka Ignition Module which is located on the front apron between the left headlight and radiator. So, not exposed to engine compartment heat. Bottom line, it did not resolve the issue.
Thank you.

TFI is only one part, there is the ECM (Engine Control Module) which is the "computer" or "brain" that controls ignition timing and fuel delivery to the engine. ECM has predefined fuel and ignition maps and uses a variety of external sensors (some which you have replaced) to determine timing and fuel delivery.. ECMs where often mounted in the engine compartment near the windshield, not sure where it is on a Chassis build.. Failing ECMs can affect engine performance..

ECM on OP's chassis is on the inside of the fire wall, just in front of the steering column. Not exposed to engine heat.

Richard

Good to know, however, "heat soak" can still apply to the ECM even if is living a a cooler environment. This is especially true if there is failing components inside the ECM (which may be surrounded with potting material which is supposed to reduce vibration and moisture damage to the ECM). If it is potted, it makes heat dissipation of the internal components much slower. Parts tend to heat up faster and stay hotter than they were designed to be at.

OP has a 26 yr old vehicle, fair chance there are failing capacitors, semiconductors or even "cold solder joints" in the ECM at the least..

Op already has changed pretty much every electronic part within the engine compartment without change to the symptoms. ECM is a common part that controls not only ignition but the fuel delivery which will affect engine operation and performance.

I would also suggest taking a look at all of the wiring harness ground connections, not unusual for vehicles of that age to start having failing ground connections and it only takes one corroded ground to foul up the works.

[RLS7201]

Gdetrailer wrote:

pilotanpia wrote:

MT BOB wrote:
Lots of F53-460 fuel pump problems, and threads,on the net.
2 things you can try,cheap and easy,replace the TFI and the fuel pump relay.
Other things to try- at your risk- when it acts up,1-loosen or remove the fuel cap
2- when it acts up, throw trans in neutral, turn off and restart engine.

I tried the TFI aka Ignition Module which is located on the front apron between the left headlight and radiator. So, not exposed to engine compartment heat. Bottom line, it did not resolve the issue.
Thank you.

TFI is only one part, there is the ECM (Engine Control Module) which is the "computer" or "brain" that controls ignition timing and fuel delivery to the engine. ECM has predefined fuel and ignition maps and uses a variety of external sensors (some which you have replaced) to determine timing and fuel delivery.. ECMs where often mounted in the engine compartment near the windshield, not sure where it is on a Chassis build.. Failing ECMs can affect engine performance..

ECM on OP's chassis is on the inside of the fire wall, just in front of the steering column. Not exposed to engine heat.

Richard

[Wes_Tausend]

...

It can't be that hard. But yes, it can be confusing, has happened to all of us... then is simple and obvious when the demon is finally found.

The engine only needs three things to run. Compression, fuel/air and ignition. I guess we could randomly brain-storm and maybe somebody will hit upon a useful idea.

It almost can't be compression. With one caveat I mentioned earlier.

If it has a knock sensor that has an extreme ******-ignition ability, then it could knock and ****** back so far as to kill power, but I can hardly believe it would ****** that much. Unless the computer is in the heat. Or any ignition module, even new does that in your case. EDIT: I see the word r e t a r d starred out above.

So if not the above, that leaves fuel and air. Since there should be a dog-house beside the driver, one could drive without the dog-house and have another observer look for problems on-the-go. Except it may run so cool when open, as to be fine if heat is a contributor. Not that it wouldn't bake the occupants as the whole house heated up. But the problems might be that the throttle body is not opening. Offhand, I can't imagine why not. Can the EGR do anything weird on these engines? It's part of the intake. There isn't a soft rubber intake hose ahead of the throttle/mass-air that can collapse when warm... is there?

Other things that can be done with the dog-house uncomfortably open is to more directly observe what the vacuum is doing when the problem occurs. By more direct I mean it is easier to connect a vacuum shop-gauge directly to a manifold vacuum source. Otherwise one may run a longer vacuum line to the cabin with the dog-house on and also observe a dash-like vacuum gauge.

A similar thing can be done with a fuel pressure gauge. Even an old mechanical oil gauge should be in the range of fuel pressure, or any mechanical water pressure gauge that has a brass bellows. One would want to be be certain that no high pressure (say 45#) fuel leak occurred. I think at least some fuel lines have a built-in fuel-line schrader valve for shop testing. Highway Patrol sometimes tap it (state shop-added valve) for motorists out of gas. It would take a bit of similar jury-rigging to get a non-specific pressure gauge connected. This extreme effort wouldn't make any sense at all until it was insured that the fuel line from the pump and tank was not somehow overheated. Then such a convoluted fuel pressure test becomes a last resort.

Lastly, I should explain how compression can change. You probably have iron heads, but if the steel valve inserts in aluminum heads, as I mentioned earlier in http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30288794/gotomsg/30288823.cfm#30288823
come loose, the intake manifold pressure drops to near zero (or ambient) with the throttle open. But even with the throttle wide open, the engine is running under vacuum (or at least some cylinders) when the inserts stick. Some cylinders are 'throttled' by the insert ring following the valve out. When a piston compresses a high vacuum, such as at idle or other port restriction, it forms very little compression. This is the reason the throttle should be jammed open during compression checks, with all the plugs out also of course.

For those that want to understand all modern fuel injection, I highly recommend this book: https://www.ebay.com/itm/384450433528 . Charles (edit: not Fred) Probst helped develop modern F.I. ground up and then taught other Ford engineers how to develop their program introduced in 1988.

Wes

[Gdetrailer]

pilotanpia wrote:

MT BOB wrote:
Lots of F53-460 fuel pump problems, and threads,on the net.
2 things you can try,cheap and easy,replace the TFI and the fuel pump relay.
Other things to try- at your risk- when it acts up,1-loosen or remove the fuel cap
2- when it acts up, throw trans in neutral, turn off and restart engine.

I tried the TFI aka Ignition Module which is located on the front apron between the left headlight and radiator. So, not exposed to engine compartment heat. Bottom line, it did not resolve the issue.
Thank you.

TFI is only one part, there is the ECM (Engine Control Module) which is the "computer" or "brain" that controls ignition timing and fuel delivery to the engine. ECM has predefined fuel and ignition maps and uses a variety of external sensors (some which you have replaced) to determine timing and fuel delivery.. ECMs where often mounted in the engine compartment near the windshield, not sure where it is on a Chassis build.. Failing ECMs can affect engine performance..

[pilotanpia]

MT BOB wrote:
Lots of F53-460 fuel pump problems, and threads,on the net.
2 things you can try,cheap and easy,replace the TFI and the fuel pump relay.
Other things to try- at your risk- when it acts up,1-loosen or remove the fuel cap
2- when it acts up, throw trans in neutral, turn off and restart engine.

I tried the TFI aka Ignition Module which is located on the front apron between the left headlight and radiator. So, not exposed to engine compartment heat. Bottom line, it did not resolve the issue.
Thank you.

[RLS7201]

enblethen wrote:
All vehicles that were built for MHs were built to meet California emissions.
Only way for OP to know is to look at his.
My "93 has a cat

In 94 Ford changed cylinder heads and the state of tune which allowed the elimination of the cat to the end run of the 460 in 97.

Richard

[pilotanpia]

MEXICOWANDERER wrote:
And the Check Engine Light stays unlit?

YES. No check engine light. The CI light did come on 4 years ago when the fuel pump failed. It comes on briefly when starting then goes off once engine is running. (Normal)

[pilotanpia]

enblethen wrote:
Sounds like it could be bad catalytic converter

My F53 Motorhome is 17,000 lbs GVWR. So, no catalytic converter installed from factory. I even confirmed this myself.

[MEXICOWANDERER]

And the Check Engine Light stays unlit?

[enblethen]

I would suggest that the OP physically look under his/her coach for a catalytic converter.

[MT_BOB]

Twomed wrote:
460 in motorhome applications was pretty famous for this. Cheap easy fix (fingers crossed for you) was to insulate the the fuel line from fuel pump to the carb. An insulating fiber riser spacer between carb and manifold could help too.

There is no carb on a 95.

[Twomed]

460 in motorhome applications was pretty famous for this. Cheap easy fix (fingers crossed for you) was to insulate the the fuel line from fuel pump to the carb. An insulating fiber riser spacer between carb and manifold could help too.

[MT_BOB]

enblethen wrote:
All vehicles that were built for MHs were built to meet California emissions.
Only way for OP to know is to look at his.
My "93 has a cat

"All F53 from 1988 to 1993 had converters. Due to cylinder head redesign and altered state of tune, all F53 from 1994 to 1997 did not have converters and met 50 states emissions requirements. The resonator on 1994 to 1997 F53 is some times mistaken for a converter. No 1998 model year F53 chassis. All F53 from 1999 to present have converters. No exceptions were made for CA."

[enblethen]

All vehicles that were built for MHs were built to meet California emissions.
Only way for OP to know is to look at his.
My "93 has a cat

[Dutch_12078]

enblethen wrote:
Sounds like it could be bad catalytic converter

The '95-'97 F53's didn't have a cat. Wasn't required...