90 E-250 is a realDOG when hot

90 Ford E250 w/ 110,xxx- but only about 50,xxx on the 302 engine. Engine mileage not important to this story, as problem stayed when engine was changed. Truck is an electrician's work truck, and loaded fairly heavy,
with big ladders on roof. So, performance and fuel economy have never been good. This is a long standing problem, (more than 6-7 years) and is annoying, but not a killer.
Truck runs pretty good when first started. Acceleration from stop, and when increasing from 25 to 40 is acceptable (for the weight and drag from ladders). However, when the engine reaches operating temp, the performance drops. The hotter the engine gets the worse the performance. On hot days w/ the temps in the 90's, the performance is so poor that even w/ accelerator pedal floored, I sometimes have to turn off the a/c to get any acceleration from a stop. In any case, once the speed gets to 40-50 it seems more "normal". Never "peppy", but it IS heavy w/ lots of airstream interference.
The other anomaly that is interesting, but not exactly correlating to the performance is the instrument cluster temp gauge. Sometimes it works and sometime it doesn't. Often when it does work, it is during the cooler weather. When the engine (and pax compartment) is fully warmed, often but not always, the temp gauge will fall down to fully left deflection (cold). This fall is after the performance loss has occurred. Sometimes the gauge never moves at all, just stays fully to the left. On a few occasions it will perform normally all day. Remember we make several service calls a day in this truck, so lots of starts, short trips, sit an hour or two and repeat. I can't correlate the temp gauges movements to anythig else! ( Yes, heat works fine in winter. We've changed the stat 3-4 times.Cooling system is flushed every other year MAX. Often EVERY year) Check engine light does not show. Yes, the lamp comes on w/ key on but not yet atarted.
I've had this complaint to 2 different independent shops and 2 mobile diagnostic visits. All 4 times there are NO codes in the computer to indicate where this might be. When the vehicle is tested by our clean air Nazi's, it ALWAYS receives a passing grade. Not sure what they check for in my part of Missouri, but for the last 6 years it has always been passed on their "fast pass" parameters. (Meaning very low emissions, I guess)
Several years ago, first shop replaced plugs, wires, dist cap, rotor? and anything else that has to do w/ "tune-up". It made absolutely no difference. Neither independent shop has any helpful suggestions other than, "well, we could try changing the (pick one) sensor and see what happens." I remind them IT'S A 90 w/ MORE THAN 100,000 miles. I can not afford to rebuild the damn thing!
So, here we are. Anybody had a similar experience? Looking for various suggestions that I can try myself. Take it to the dealer and spend $500-$1000 is not one I'd think makes much sense.
Thanks, Gary Kasten
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The first thing that comes to mind (especially given the temp gauge anomaly) is a low coolant condition. Low coolant level may result in the gauge sender and the ECT not being submerged in coolant during operation. If the ECT is not bathed in water, it cannot provide the proper signal to the ECM, and incorrect fuel metering results. However, since you indicate that this is an ongoing problem that has lasted through several cooling system flush/fill cycles, a redundant low-coolant level seems unlikely. Perhaps the truck is actually overheating and coolant in the top of the motor is starting to boil? This should be obvious, of course, and repeated overheating would likely have caused significant damage by now. An overheating problem will also cause the PCM to pull out spark lead to avoid detonation, and this would definitely kill power. Perhaps you should obtain a good, numbered analog temp gauge to determine with certainty if the motor is running within normal temp ranges or if it is getting too hot.
Just a couple of thoughts to mull over... Mark
On Fri, 16 Jan 2004 02:34:17 -0700, VideoGuy wrote:

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"VideoGuy" <gkasten at brick dot net> wrote in message

when
performance
You never mention if the fuel filter(s) have been changed regularly or at all. Have your shop check the fuel pressure on the rail... it sounds like you may have a combination problem involving the filters, and/or pressure regulator, and/or fuel pump. Your contention that it didn't change with an engine swap supports this too. The fuel pump may even have been defective since new or nearly new, or the pickup screen could be compromised or blocked.
Rob * * *
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an
Fuel filters have been changed and there is never any apparent blockage, and no change in the problem with a new filter. I don't know if the first shop ever checked pressure at the rail either. I'll ask them to check their records.
Question: If this is a fuel pressure problem, why would the truck run OK when cold? This is not a smart-ass question. I don't understand today's modern fuel and ignition systems past the basics. So your comment confuses me.
Thanks. Gary
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"VideoGuy" <gkasten at brick dot net> wrote in message

confuses
Gary,
I think the problem I ran into with these same symptoms once was because the fuel was boiling in the rail on very hot days with only about 8 psi. Cool days were a tough start sometimes with a very hot engine, and then no problems through the winter. Truck ran great when first started, then OK at speed, but when you put your foot in it for more go there just wasn't any once warmed up. The biggest clue was when you turned on the rear defroster with the heater fan on high, you lost power on accel, until letting off a little when it would pick up a little. Also, the injector duration is longer when cold, as there is no choke. There were no EEC codes on ours either.
New pump, new regulator, new filters, and it was like new again. The pump was likely taken out by a siezed regulator who knows how long ago, it was just enough pressure to barely run the truck. Check for specs, but 40-45 psi on the rail Schrader fitting should be good, under this, and certainly under 20 psi, is too low and would start to cause the problems you describe.
Did you replace the whole engine TB to pan - with all accessories, or a long block, or a short block?
Rob * * *
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long
The engine replacement was done while I was out of town, so some of the details are unknown to me. Also since it was about 7 years ago, I'm getting fuzzy on what I did know. Anyhow, I believe it was a short block because they also sent out the heads to be refurbished at the same time.
Your suggestion of replacing the fuel pump, regulators and filters sounds like a viable solution. Is this a potential DIY job for an ambitious "Sunday mechanic"? I'm not familiar with the regulator. Where does this live? If I have it done, any idea what is a fair price. Live in the St. Louis, MO area.
Thanks, Gary
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On Fri, 16 Jan 2004 03:34:17 -0600, "VideoGuy" <gkasten at brick dot net> wrote:>90 Ford E250 w/ 110,xxx- but only about 50,xxx on the 302 engine. Engine

Just a shot in the dark, but have you checked for a dirty air filter or some other restriction in the air intake?
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Yes. Air filters changed many times. Air inlet from filter to intake also cleaned. No restrictions found anywhere.
Gary
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have you replaced the temperature coolant sensor and switch (latter for the guage ) coolant sensor regulates fuel mixture the ohms change when the engine gets warmer the ohms change and so the fuel mixture also changes ,and not necceraly show up on machine the pulls the codes also a master mechanic told me never to use anything but copper for gaskets (in place of permatex or the blue stuff, said the material creats a reaction that grounds all the sensors)hope this helps OP. "VideoGuy" <gkasten at brick dot net> wrote in message

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