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 > Your search for posts made by 'maillemaker' found 4 matches.

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RE: Vapor lock 1990 E350 EFI 460 engine?

Just to let folks know how this ended up. The root of the problem is a failure of the in-tank fuel pump. I did not think to check it, because I had replaced it just a few years ago. These early 1990s vehicles were early transitions from carbureted engines to fuel-injected engines. The small in-tank pump was not sufficient to push the fuel up to ~40 PSI needed for fuel injection, so they simply added a high pressure pump in the circuit. The high pressure pump is mounted on the frame rail under the driver's seat. The way the system works is this: The in-tank pump pumps fuel out of the fuel tank towards the high-pressure pump, which then boosts the pressure up to around 40 PSI to the fuel rail on the engine. The injectors drink what they need to supply the engine at any given throttle/RPM, and the excess fuel not used by the engine is routed back on a return line back into the fuel tank. When the in-tank pump fails, the high pressure pump is strong enough to suck fuel all the way from the back of the vehicle, through the dead pump, and run just fine - under most conditions. However, I installed a thermocouple sensor on the return fuel rail just as it leaves the engine compartment. On a hot day, that sensor was reading about 125F. If you stopped the vehicle and sat for 10 minutes, that sensor would run as high as 145F. After you start the engine and fuel gets flowing through the line again, it quickly drops back to around 125F. I used an infrared thermometer to read the temperature of the fuel tank itself after extended (hours) running at interstate speeds. The tank wall was reading about 110F. Here is what I believe is happening: Ethanol-based gasoline starts to boil at around 175F. The boiling temperature of liquids is directly depended on ambient pressure. This is why it is hard to heat water hot enough to cook with on top of Mt. Everest - water there boils at only 154F. This is because the air pressure there is only 4.89 PSI as opposed to around 16 PSI at sea level. When the in-tank pump dies, the high-pressure boost pump is sucking hot fuel through about 4-5 feet of fuel line, and a dead pump. Since the high-pressure pump is pushing 40 PSI downstream, it is capable of sucking that much from upstream. We can't be sure exactly how much resistance there is to suction so we can't be sure what the actual pressure differential is. But my suspicion is that the high-pressure pump is causing enough of a pressure drop in the upstream fuel line that the fuel there boils. Once it boils, the high-pressure pump cavitates and can no longer pump any fuel. With the engine off for about 20-30 minutes, the fuel cools enough to turn liquid again, and the engine will again run until the situation repeats. You will see this with a very low PSI reading on the fuel rail. When I finally caught it in the act, I was reading around 11 PSI or less. Less than 20 PSI and the engine won't run much, if at all. I ended up installing digital ammeters to both the high-pressure and in-tank fuel pumps, with readouts in the cab, so that I can monitor the current draw of each pump independently. I also have installed a digital fuel pressure gauge which picks up from a sending unit on the fuel rail. Ultimately, the Airtex pump I had replace five years ago had died. When we got it out of the vehicle and I disassembled it, one of the brushes was gone, and the other was just a tiny nub. We replaced it with another Airtex pump, and I still had erratic running. I finally located a new old stock Motorcraft fuel pump. This completely fixed the problem. Not only that, but because the sending unit was properly calibrated for my tank, my fuel gauge read correctly once again. This problem is very hard to diagnose because the high-pressure pump completely masks the problem until extended operation at high temperatures. High temperatures with short-distance driving won't trigger the problem. If it's cold out, you may never see the problem (although I finally did catch it with the digital fuel pressure gauge in the middle of winter, with snow at one leg of the journey, after an 11-hour drive from Virginia to Alabama). Because of the highly intermittent nature of the problem, very few complaints of this nature you find on the internet end up being resolved. Although, I have found a few posts after more intense searching where others have found this same root cause.
maillemaker 04/26/21 08:59am Tech Issues
So are there any decent 1141 replacement LEDs these days?

About 5 years or so ago I bought one of those cheap-o twenty-count boxes of LED lightbulbs for interior RV fixtures. 1141 bayonet base style. They look kind of like this: They worked OK to start with, but very quickly they started giving off an electrical/ozone kind of smell, and individual LED banks on the bulbs started flickering and eventually burning out. Most of them still work but are partially burned out to one degree or another. I'd like to buy some more and I hope that over the years they have gotten better, but reading Amazon reviews many are still experiencing similar problems. Then, too, it's hard to trust online reviews today with all the fake padding of reviews going on. This one seems highly rated: Can anyone suggest quality 1141 LED replacements? Thanks, Steve
maillemaker 04/26/21 07:15am Tech Issues
RE: Ripping up carpet, replace with vinyl, fuel pump hatch.

Back around 2013, we were on a trip, and the RV died. The fuel pump relay had burned up. I believe this was a precursor to the pump itself dying. Within a year, the pump itself burned up. When I say "burned up", I mean it had melted the metal of the pump. When this burned up, it also burned up the inertia cutoff switch. This was the OEM pump. It was replaced in 2013. The shop that did the replacement put the wrong pump in. Long story short - Airtex's web site did not take into account a part number change in September 1990 so they gave out the wrong fuel pump part number. Made the gas gauge run backwards. So, I had to have it replaced again with the correct one (E2060S). This pump probably failed 3-4 years ago but I never knew it or suspected it until I got a digital fuel pressure gauge installed on the fuel rail and caught the failure in the act. I also installed ammeters on the line to the high pressure pump and at the inertial cutoff switch (I would prefer to have installed it at the in-tank-pump itself, but I cannot access it). The pumps are getting the correct amount of voltage and draw the proper amount of current (when the in-tank pump is running). I believe the problem is simply that Airtex pumps are not quality pumps. Anyway. Floor time. I'm thinking of cutting out a square opening, and fencing the perimeter with 2x4 or similar framing structure. This will give the hatch and surrounding floor something solid to sit on so there is no give when you walk across it. The removable plug/hatch will be floor foam with sheet metal on top of that, and the vinyl on top of that. I will drill small holes around the perimeter of the vinyl to allow flat-head screws to recess down into the vinyl and bottom out on the sheet metal. This way there will be no screw heads protruding up from the vinyl. I was not going to bother with a hinge as hopefully I won't be removing this hatch often. There will be another piece of sheet metal down on under the floor foam on the bottom "hull" plate of the RV, which I'll install with regular sheet metal screws. This will support the hatch and anyone standing on the hatch. When the hatch is removed, and the bottom hull plate remove, I should have access to the top of the fuel tank.
maillemaker 07/26/20 07:31am Tech Issues
Ripping up carpet, replace with vinyl, fuel pump hatch.

So, some back story: I have a 1990 Winnebago Warrior on an E350 chassis. I have been having fits with the fuel pump. It died in 1993, was replaced with the wrong pump, finally got Airtex to admit they specified the wrong one, they sent me the correct one (E2060S). Got it replaced again. Since 2016 I have been chasing an intermittent shutdown while hot problem. I have replaced nearly every electrical thing on the engine. Replaced fuel filter and high pressure frame rail pump. Never thought about the in-tank pump since it was "brand new". Well, I finally installed a digital fuel pressure gauge, and finally caught the failure in the act. Typically you have to run on a hot day, and then, when you slow down, it will die like it is out of gas. I initially suspected vapor lock, even though this is a fuel-injected 460 engine. I bound a thermocouple to the return of the fuel rail out of the engine compartment and the temp never got over 128F while driving at interstate speeds. If you stopped and shut off the engine for a few minutes, the temp would go up to about 145F, but as soon as you started the engine it would go back down again. Not a vapor lock problem. Engine runs about 195-199F with AC on on a hot day. Transmission is about 180F on a hot day. This is from digital gauges I have installed. Finally, when it died and I caught it in the act, fuel pressure was only 12 PSI on the rail. Also, I installed a digital ammeter on the high pressure pump, and another on the trunk at the inertial cutoff harness. Thus I could see the current draw from the high pressure pump, and the total current draw of the in-tank pump and the high pressure pump together. Well, I discovered that they read the same. This clued me in that the in-tank pump was not running. I confirmed this by disconnecting the fuel line from upstream of the high pressure pump - sure enough, no fuel from the tank line. Also, I put a mechanic's stethoscope on the tank - no sound. So if you google "Ford 460 vapor lock" you will discover that there are countless threads out there with people with this exact same problem. My guess is that their in-tank pump has died, and the high pressure pump usually is able to siphon gas from the tank and pump it up to the engine, unless the fuel temp gets up over 100F. My guess is that when high pressure pump sucks from the tank, the low pressure it creates upstream of the pump is enough to reduce the boiling temperature of the gasoline enough for it to boil and then the high pressure pump cavitates. Anyway, I had the pump replaced AGAIN, and when they gave it back to me, I hooked it up to 12V power. Sure enough, it did not work. Then I wiggled the spade contacts at the actual pump itself, and lo and behold, the pump started working. The pump worked fine - it just had bad electrical contact at the pump connections! Well, I had a new Airtex E2060S installed, so I figured what the heck, I've got a new pump now. Well, as soon as I got it back from the shop, the gas gauge is wandering all over the place from time to time. And the second weekend after I got it back (shop was closed the week after 4th of July) it died AGAIN, same symptoms. Dies while hot, 12 PSI on the rail, no current draw from the in-tank pump, wait 20 minutes and it works fine again. Well my shop says they will replace the pump again. But I'm tired of having to have the shop do this for me because it involves dropping the tank. So, to the meat of the story. This RV has wall-to-wall carpet. I've never liked this, as it gets dirty in a hurry. I would prefer vinyl flooring. While I'm at it, I want to cut an access hatch in the floor to get at the fuel pump. I'd like some suggestions on how to go about this, and make a nice looking end result with the hatch in the floor. Thanks,
maillemaker 07/25/20 10:10pm Tech Issues
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