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Warm weather 460 problems

Problem occurs in warm weather. engine loses power, hesitates and stalls. Won’t start until engine cools, sometimes 1/2 hour. Problem is worse in trrafic or moutain driving.

1992 Airstream class B motorhome. Started in AZ climing moutains in the Tonto Basin and repeated a few times in the moutains of Or, Wa,. Semms to be getting worse now; happened last week in Odessa TX in 80 deg. temps. in traffic. Ran ok after getting out of town. Also noticed the fuel consumption is getting poor. Help, let us know if you solved the riddle.

Possibly could be vapor lock, where the fuel in the fuel line vaporizes and locks up the fuel pump. The fuel pump is designed to pump fluid, not vapor. There seems to be a heat build-up somewhere in the fuel line causing the fuel to boil. Did you have any exhaust work done recently? Is the engine in good tune? Not running too warm?

Temp. gauge is just below center in normal range, no sign of coolant over heating. Fuel pump is in tank on this fuel injected model. It does act like vapor lock I had on old vehicles. No recent work done on the rig other than fuel filter and normal oil changes.

Since this is a '92 model Ford the ignition system should be the TFI-IV type. These systems were prone to heat related failures and the symptoms can vary quite a bit from cutting out, dying and not starting for a while, or dying and never restarting.
Warmer weather is when these things really start acting up.

Testing the module is often pointless because a test may show that it’s fine. The module is the little gray rectangular box on the side of the distributor. If the distributor is moved while changing the module setting the ignition timing with the SPOUT wire disconnected is critical.

If you change the module yourself (easy to do) you will need a 4 MM or 7/32 nutdriver or deep socket. When installing the new module you MUST apply the special electrolytic grease that comes with the new module or it too will fail. Hope that helps.

For more info on the TFI problem do a net search for TFI-IV Settlement.

Thank you much for your reply, I sure will give it a try. I thought it might be O2 sensor now? It runs fine before it heats up.

It’s not the O2. The running joke about the TFI module is replace it and keep a spare in the glove box, just in case.

The hotter the weather the more prone they are to failing. These backside of these modules get blistering hot in just a few minutes with the key on no matter the temp outside. The inside has a tiny printed circuit that is encased in jelly and excessive heat caused by the outside air temps can cause some of the circuits on the circuit board to fail. Once cooled, it will run fine again for a varying amount of time.

The most common symptoms are the appearance of running out of gas or pulling up to a stop and the engine dying.

Sure sounds like you are right on. I will let you know as soon as I try it. I had to replace the coil once when having trouble in wet weather a few years back . You sure sound like you know what your talking about. Thank you so much. I bought this rig from my dad and we have really had good times in it. It has been great and worth putting a few bucks bin it once in awhile.

I’ve suffered through the TFI Sitting on The Side of The Road Syndrome more than once, and on several different vehicles. Very nice on a 100 degree/90% humidity OK summer day.

The way I finally cured the problem on my vehicles was by mounting the module inside of the air cleaner housing. I used a piece of finned aluminum aircraft heat sink and mounted the module to that. The heat sink was then bolted inside the air cleaner housing with self-locking nuts and a foot long wiring pigtail was made to connect it to the wire harness.
This assures that whenever the engine is running air is constantly being pulled over the module/heat sink and that cured my TFI problems forever.

About 7 or 8 years ago I got a letter in the mail advising me of my eligibility to be part of the class action suit against FOMOCO over these modules; and one of the cars I did not even own anymore. I filled out the forms with the VINs, enclosed the receipts for my module purchases, and due to the wheels of bureaucracy turning slow, about a year later I get checks in the mail for reimbursement.
It’s doubtful after this much time you could get in on this deal.

I googled TFI-IV Settlement and found info. I might try for reimbursement or maybe go to a Ford dealer and ask for the module. We are down in Crane Tx today, about 3,000 people and the biggest town in the county; probably won’t get much done today, Sunday. I plan to stay here a couple days then head for Odessa about 30 miles north and see what I can do there. Looks like the hardest part of the job is pulling the engine cover on my van. Hope I can make it that far. If it stops before I get to Odessa I have a little motorcycle in a trailer so I will make it one way or the other. I might try your retro fix later.

It did it again in Hobbs NM temp around 90 sitting by a Autozone tohight. I tested the igintion mod. over 12 times trying to get it to warm up enough to fail on the tester but it kept passing. I think I will test the fuel pressure in the morning then buy a Ignition Mod. and hope it works. Around 50 for Mod.

I have found that testing the modules is an exercise in futility and have even found this to be true of the older Ford DuraSpark modules. I’ve repeatedly tested a DS module with a Snap-On tester and found the module to be faulty even though the tester showed it to be good 6 times in a row.

The modules that have failed on my vehicles were also shown to be good when tested repeatedly.
The module also provides a signal for the ECM which then uses this signal to activate the fuel pump relay.

I tested the fuel pressure today while running the rig hard and after about a hour the pressure started going down. Pressure is supposed to be between 28-45. When I first tested it was at 39 snd it stayed there for a long time until I started running it hard in the heat of the afternoon. When I ran it for about an hour under a load in the heat the pressure started going down and finally after it went down to 20 and lower and the engine stalled. I started installing a new pump this afternoon. I will let you know what happens in the future.

Based on that test, it does sound like a failing fuel pump. Also be sure to change the filter on a regular basis as an engine can run fine with a partially clogged filter. A clogged filter will also shorten the pump’s life by making it work harder.

In regards to that ignition module I would certainly consider changing it if it’s the original or at the very least, carry a spare one in the glove box. They are that much of a problem. Good luck.

Haven’t experienced this kind of problem yet. But if its really getting worst, then you should drive it right away to the dealer and auto parts shops for checking.