Heat Soak Problems

[farmersammm]

https://www.autosafety.org/ford-tfi-...ss-settlement/

This I believe was the device that went on the GMC Savana Van.

Sincerely,

William McCormick

Mine is on the fender, mounted in a heat sink with big aluminum fins. It was one of the things I heated with the heat gun........matter of fact, I got it too hot to touch I had no idea those heat guns were so powerful. Anyways.........just kept running without a hitch when hot.

[CAVEMANN]

Sammm, does it have an emergency fuel pump shutoff, if so it should be in the right side kick panel, some were notorious for the terminal blocks melting and causing a bad connection, what year is the truck?

[farmersammm]

Sammm, does it have an emergency fuel pump shutoff, if so it should be in the right side kick panel, some were notorious for the terminal blocks melting and causing a bad connection, what year is the truck?

I never even considered the inertia switch (doh!) It's something that's out of sight out of mind. The 94 has it behind the kick panel on right side, just under the glove box.

[farmersammm]

I happened to look at my Emails, and noticed the receipt from Paypal for the probe.

It showed a payment to about a 3/4" long string of Chinese characters I didn't open the Email...........never know.........might unleash a horde of MIDGETS in my puter

I explicitly bought from a "US' seller. Well..........I'm thinking these Chinese companies are just using an address in California for purposes of doing business on Ebay. Although, the DHL tracking number shows it processed through Compton last night. Maybe some sorta industrial park small storefront/warehouse unit??????

[farmersammm]

The stinkin' probe last scanned thru the Grand Prairie, Texas facility Be lucky if I get the stinkin' thing by Tuesday

[farmersammm]

The probe showed up today

I scanned the specs for those interested. I imagine they're the same as all the other brands, as they're probably made by the same people (Hantek)



Considering what the others cost, once they're labeled differently..........this appears to be identical for about $55

[farmersammm]

I found two good videos on the subject. I'm not familiar with this sort of testing,, so I'm going off tutorials on YouTube.





Both of my trucks never set a "lean" code when they run out of fuel, or the pump quits...............so I think this is the only way, short of hooking up the pressure gauge, and driving while waiting for a failure.

Probe specs are in the previous post.

[William McCormick]

I found two good videos on the subject. I'm not familiar with this sort of testing,, so I'm going off tutorials on YouTube.





Both of my trucks never set a "lean" code when they run out of fuel, or the pump quits...............so I think this is the only way, short of hooking up the pressure gauge, and driving while waiting for a failure.

Probe specs are in the previous post.

That guy in the first movie was very logical. Very good stuff, thank you.

Sincerely,

William McCormick

[farmersammm]

Got after it today................

First test: Pressure regulator WITHOUT vacuum. This means that the fuel demand is high, and the pressure has to be high, which means that the pressure regulator RESTRICTS flow. Less gas flows back to the tank. (This is an old system WITHOUT fuel pump control.......it just runs flat out all the time)

60,000 (miliseconds in a minute) / Delta 12.7 (the time between the brushes hitting 8 commutators) = 4700rpm

Second Test: Pressure regulator WITH vacuum. This means the engine is idling, and the pressure doesn't have to be high........just enough to supply the injectors at low RPM. The pressure regulator OPENS UP to allow gas to go back to the tank in order to relieve pressure.

60,000/10.6 = 5600rpm

RPM on a Ford V-8 in this year should be around 6000rpm, from what I've been able to gather. AT ALL PRESSURE, AND FLOW, DEMAND. This thing is bogging down when it has to push pressure.

How it works.................Domestic pumps in this year, and maybe even now, have 8 commutators. This translates to 8 humps in the waveform. Setting the cursor so that it divides the waveform into 8 distinct humps gives me the time from start to finish as those humps complete one revolution. It's like 8 on-off cycles, which make up one full revolution of the pump motor.

To verify............I ran a quick test on the F-150. It has a higher pressure pump. There was no variance in RPM, or Amp draw, at any pressure. Steady as a rock.

So...........we're right back to vapor lock!!!!!!!!!!!!! Old time pre fuel injection wisdom. If it quits when it gets hot, and acts like it's running out of fuel, it's gotta be vapor lock. I'm still here on the diagnosis.

For S&G's I looked up the pressure at which vapor lock can occur............ https://www.mckinseyenergyinsights.c...apor-pressure/

I have no idea whether my pressure is going that low when everything is hot. This truck regularly gets so hot that you cannot touch the front fenders, or hood, when the ambient temp is relatively high,, and it's been pulling a load. Ton of heat coupled with a pump that's definitely out of spec.........pressure test, and rpm test..........I'm thinkin' it's the pump. And, the truck will restart, and run ok when it's been sitting for an hour. All points to the pump.

[William McCormick]

Got after it today................

First test: Pressure regulator WITHOUT vacuum. This means that the fuel demand is high, and the pressure has to be high, which means that the pressure regulator RESTRICTS flow. Less gas flows back to the tank. (This is an old system WITHOUT fuel pump control.......it just runs flat out all the time)

60,000 (miliseconds in a minute) / Delta 12.7 (the time between the brushes hitting 8 commutators) = 4700rpm

Second Test: Pressure regulator WITH vacuum. This means the engine is idling, and the pressure doesn't have to be high........just enough to supply the injectors at low RPM. The pressure regulator OPENS UP to allow gas to go back to the tank in order to relieve pressure.

60,000/10.6 = 5600rpm

RPM on a Ford V-8 in this year should be around 6000rpm, from what I've been able to gather. AT ALL PRESSURE, AND FLOW, DEMAND. This thing is bogging down when it has to push pressure.

How it works.................Domestic pumps in this year, and maybe even now, have 8 commutators. This translates to 8 humps in the waveform. Setting the cursor so that it divides the waveform into 8 distinct humps gives me the time from start to finish as those humps complete one revolution. It's like 8 on-off cycles, which make up one full revolution of the pump motor.

To verify............I ran a quick test on the F-150. It has a higher pressure pump. There was no variance in RPM, or Amp draw, at any pressure. Steady as a rock.

So...........we're right back to vapor lock!!!!!!!!!!!!! Old time pre fuel injection wisdom. If it quits when it gets hot, and acts like it's running out of fuel, it's gotta be vapor lock. I'm still here on the diagnosis.

For S&G's I looked up the pressure at which vapor lock can occur............ https://www.mckinseyenergyinsights.c...apor-pressure/

I have no idea whether my pressure is going that low when everything is hot. This truck regularly gets so hot that you cannot touch the front fenders, or hood, when the ambient temp is relatively high,, and it's been pulling a load. Ton of heat coupled with a pump that's definitely out of spec.........pressure test, and rpm test..........I'm thinkin' it's the pump. And, the truck will restart, and run ok when it's been sitting for an hour. All points to the pump.

Is the amperage too low? I cannot make out what each division is supposed to be representing?

Sincerely,

William McCormick

[farmersammm]

Is the amperage too low? I cannot make out what each division is supposed to be representing?

Sincerely,

William McCormick

My scope isn't the best on the planet. It won't measure amps in "scope" mode. The scale you're seeing is volts. Which is ok for just seeing rpm, but not good for measuring current draw. I can directly measure current with the graphing multimeter function, and it shows 6amp draw.........which is ok for this pump(?). I did check the F-150, and it draws 9amps. So.............my amperage draw might be too low too. I did check part #'s, and the pumps seem to be identical on both trucks. I'm not too sure about this either................they both run at different operating pressure........the 4.9l runs at higher pressure than the 7.5l.

BUT I'm thinking I can go into a specific component test mode for fuel injectors, and the thing might measure amps instead of volts.

[farmersammm]

Hey Bill................ It seems that the current probe converts current flow into milivolts, which can be converted, using mental gymnastics, into amps. I'm on the verge of figuring it out I think Never used a scope to measure amps before, so it's a learning curve

I'll get back to ya when my moron brain has it figured out

[farmersammm]

I got 'er fingered out!!

The Hantek low amp probe is different from those mostly used for automotive stuff, but it's same same (sorta).

This probe has two settings. 1Mv = 10Ma...........and 1Mv = 100Ma

We know that 1000Ma = 1amp



My voltage range is 50Mv per division on the vertical axis.

My time is 2Ms per division

So..............................we gots approximately 150Mv output from the probe.

150Mv x 10Ma = 1500Ma

1500Ma / 1000Ma = 1.5amps

The pump is TOAST . Or there's excessive resistance in the circuit. Or my calculations are wrong

Now why the graphing multimeter function gave a bad result (amps too high compared to scope), I dunno (shrug) I don't fully understand this aspect yet.

[solman]

What's the year model and make of the truck?
What engine is in it?
Have you eliminated the basics such as fuel filter and basic tune up?
It does sound like fuel starvation problem which can be a clogged filter or screen in the tank on the fuel pickup. After the truck Sits a while the clog eases somewhat as there is no longer any pressure on the filter and it will run again for a while.
Just a thought and easy enough to do the filter for a few bucks.
Also check for a restricted exhaust system problem.

[farmersammm]

This has been a really difficult learning curve, and I've spread some misinformation.........I apologize

After watching literally hours of YouTube videos, and trying to understand manuals written for someone who ACTUALLY has a clue................I finally got it. WHEW!!

The basic screen has a BASELINE. It's labeled "A".

The divisions ABOVE AND BELOW that baseline are volts, millivolts, and microvolts.........depending on how you set the scope up.

This is the default location for the baseline. Always in the middle.

You can reposition the baseline if you need to measure volts in excess of half the horizontal divisions on the screen. In this example, each division has been set to represent 5V (A:5V lower left hand corner). I can measure a signal up to 35 volts now, because I have 7 divisions above the baseline.

The screen shows a flat solid line on A (baseline). This is because no voltage is being measured. This is 0

If I were to measure a constant DC signal, the solid black line would move ABOVE the baseline (A) in divisions corresponding to the amount of voltage I'm measuring.

Now, let's look at what was actually measured on the truck (sorry about the glare, and poor photos)

This is looking at the Graphing Multimeter. The solid line is one division above the baseline, plus a tad. Now look directly below the divisions. The number second from the left identifies what each division represents. In this case..........each division is 5amps (5A/d). The digital display in the upper left shows the amperage (5.88). This corresponds with the location of the solid line on the grid above the baseline. You can see the line is about 1/5 the distance into the next division. (Before we go onto the scope, you might be wondering why the solid line doesn't show any waveform.....it's because the minimum time division on the GMM is 5 seconds, and the variation in amps is too small for the scale on the GMM).

Now let's see how it looks on the scope.

This is current ramping the fuel pump. Measuring same thing as the GMM, but now we can see the current build between the commutator bars on the motor as it spins. From low amperage to max amperage on each wave.

The baseline is at A. There are 7 divisions above A. Looking directly underneath the graph, you see what each division represents (A:0.1V). Each division is 1/10 volt, or 100 milliamperes.

Our highest peak on the wave is a tad above the 6th division, or 600mA

The amp probe is set at ImV/10mA. This means that we multiply the 600mA reading by 10, which gives us 6000mA, or around 6amps. Thus, the oscilliscope agrees with the Graphing Multimeter (GMM)

Next, we have to interpret the peaks and valleys in the oscilliscope pattern. Each peak is the max amp draw as the motor spins. The valleys are the lowest amps drawn as the motor spins. You're never going to get back down to the baseline if the brush/commutator are passing current as they interact. The only time you'll get down to the baseline is if you have a "dead" commutator (this is where you have to bang on the gas tank to get the pump going again).

So, the pump in the truck is drawing 6amps peak, and 5amps minimum, as it spins. It's not suffering from a dead spot.

[farmersammm]

What's the year model and make of the truck?
What engine is in it?
Have you eliminated the basics such as fuel filter and basic tune up?
It does sound like fuel starvation problem which can be a clogged filter or screen in the tank on the fuel pickup. After the truck Sits a while the clog eases somewhat as there is no longer any pressure on the filter and it will run again for a while.
Just a thought and easy enough to do the filter for a few bucks.
Also check for a restricted exhaust system problem.

You might be in the ballpark, but with a twist.

This truck has a constant problem. The fuel tank gets water in it when it rains. Not all the time, just when the drain in the filler neck well gets plugged. This truck has the neck set up so you fill the tank from the TOP of the bed. Stupid design, but it is what it is. Debris plugs the little hole at the bottom of the well. I keep meaining to hog the hole out, but never get around to it. Water fills the well, and it gets in through the filler cap.

When this happens, I have to pump the water out through the Shrader valve on the fuel rail. There's no way to siphon the tank through the filler neck. Something blocks the siphon hose from entering the tank.........it only goes in as far as the filler hose between filler neck, and tank.........and won't go in the rest of the way.

Last time I did this, the fuel just dribbled out..........not a good full flow.

I thought I plainly addressed the specs for this system in the video, but maybe folks missed it.



7.5l should run 30 at idle, and up to 45 under load, or at throttle snap. I get 30 at idle, but only go to 36 at throttle snap. What I said, and illustrated, in the video........along with saying I'd like see it go higher at the snap.

The pressure never drops below 30 at any time in the "shop", but I have no idea what it's doing on the road when it gets extremely hot under the hood, and possibly the fuel pump gets hot. Tests have confirmed that it does draw 1amp higher when it runs in the shop for an extended period. Dunno what the draw is when it's actually running under load with different demand, and heat.

I've suspected vapor lock since the beginning, and I'm still pretty much convinced it's happening

If that fuel pressure drops below 15 when the truck is hot, the fuel will boil. When it cools, the problem will resolve itself. This problem only occurs after pulling heavy. Always on the return trip when the truck is loaded.

I replaced the filter a couple of drain cycles ago, but that's been a while. Probably had to drain the tank at least twice since then. It's possible that the water has started to rust the tank, and crud has been sucked into the filter.........OR MORE LIKELY BLOCKED THE STRAINER ON THE PUMP. This would cause a flow issue.

If flow is decreased, pressure will decrease down the line under high demand. Static pressure won't be affected. But, because this is an older "return" system, pressure could be taking a hit all the time, although it's pretty close to spec at idle, and never drops below 30 on a throttle snap. I'd suspect poor power, as I've experienced for about a year now, but I wouldn't expect a shutdown unless the pressure is actually dropping close to 15 when hot. 15 won't result in a no start, but it could result in a vapor lock situation.

So, now that I've figured out what I'm seeing on the scope, the next step is to look for restrictions in the fuel line, or pump intake. I'm not totally ready to condemn the pump.

[farmersammm]

Put about 40 miles on it this evening, and no problems Gas mileage is back to normal...........it took about 7.5 gallons to make the trip. Power was pretty good..........70mph when needed. No hesitation, and NO STINKIN' VAPOR LOCK WHEN IT GOT HOT ON THE WAY BACK



I'd like to see another 5lbs on the snap, but it's running well...................so for now, it's good to go.

The fuel filter was the culprit. And......if I ever find the time, I'd like to drop the tank, clean it out, and put a new strainer on the pump.

I guess it seemed like a long drawn out process, but mostly the time was used to learn how to use the scope. I've never had to do actual voltage measurements on the thing in all the years I've owned it. Knowing what I know now, it really boils down to about a 15 minute total test including pressure, and amp ramping. This was the first fuel problem I've had on any of my 1994's. I guess it says a lot for that particular year.

Would I just guess, and slap a filter on it?????? Y'all know me It has to be a right diagnosis before I do anything. I hate throwing parts at a problem

It's a real pleasure to have it back up and running again. There isn't a modern gasser that will out pull these old 460's. I get a kick out of flyin' by them on a four lane

[farmersammm]

Only two pages. I must be slipping in my old age

[William McCormick]

Only two pages. I must be slipping in my old age

Happy to hear you got her done.

Sincerely,

William McCormick

[Zimm]

Glad thats fixed, now you can get onto the pickup. Looking forward to what you find there. I have the same issue- low pressure from the rear tank but not the front. First thought was the pump, but a new one didn't fix it. It will run along at part throttle, but lay down when more power is needed. Front tank runs fine. From what I read, there is a check valve in the system that could be bleeding off pressure.

More diagnostics needed here too.

[ronsii]

Glad thats fixed, now you can get onto the pickup. Looking forward to what you find there. I have the same issue- low pressure from the rear tank but not the front. First thought was the pump, but a new one didn't fix it. It will run along at part throttle, but lay down when more power is needed. Front tank runs fine. From what I read, there is a check valve in the system that could be bleeding off pressure.

More diagnostics needed here too.

Sounds like the common issue with the multi tank fords the check valve on the fuel pump assemblies goes bad and let the other pump feed back into the bad pump(tank)... symptoms are low fuel pressure on one or both tanks, slugishness, running rich,etc....


Fix: replace the bad fuel pump/s or some people have actually put in secondary check valves...

[Willie B]

When it was a couple years old, my 2001 Savana van had the 4 wheel drive conversion. The fuel pump cut out regularly. Took it to the dealer several times for fix.

They said it wouldn't act up for them. I needed the truck, so I added key on power source controlled by a manual switch. Mr. Goodwrench kept removing my added wiring. I got mad, said if you can fix it so it doesn't quit on the road, go ahead and remove my extras. Otherwise LEAVE it there!

I drove it that way a few more years. Eventually the gas tank leaked. In all the wrestling installing a new tank, we discovered a mating plug in the wiring harness above the transfer case. Because the transfer case is not original, the harness was stretched.

[Zimm]

Sounds like the common issue with the multi tank fords the check valve on the fuel pump assemblies goes bad and let the other pump feed back into the bad pump(tank)... symptoms are low fuel pressure on one or both tanks, slugishness, running rich,etc....


Fix: replace the bad fuel pump/s or some people have actually put in secondary check valves...

Yeah. I was under it yesterday looking at the bed bolts. They don't look too rusty. Going to start soaking them with PB Blaster. I like the idea of pulling the bed to be able to get to everything from the top. Pulling those tanks out is a PITA.

Got other stuff to do on that truck after all these years too. The #1 plug is rusted and rounded. Not good. I ordered a couple of special sockets from SK to see if I can get it out without pulling the head. It runs OK, but is overdue for an ignition tune up. The other 5 loosened up fine. After that, pan gasket, rear trans seal leaks, brakes. After 195K, its time to catch up on stuff.

Any ideas for how to get that plug out would be welcome.

[farmersammm]

Might be the same sockets you ordered. Anyways, I thought this was a good idea. I've never seen these before.

[Willie B]

"Any ideas for how to get that plug out would be welcome."
If you can get around it, slip a very large nut over it. MIG it to the steel.
If you can't make room, break off the porcelain. Slip an impact socket over it, and weld it to it with 6011 filler. The heat from welding might help, but be careful not to get the head too hot.
It'll take a tremendous lever of patience wiggling the socket back & forth, I think it'll loosen.

Friday I had two grade 2? bolts rusted solid in the end of two shafts, and broke off 1/4" deep. Only welder I had was MIG. With patience I built up flush, then a good sized ball of filler sticking out. It took 15 minutes each of wiggling with vice grips to free the thread. One of the two was bent halfway through the thread.