1988 Ford F-150 Truck - Loping, Dying Out at Stops, Turns, When Idling
03-25-2015, 10:59 AM
#1
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1988 Ford F-150 Truck - Loping, Dying Out at Stops, Turns, When Idling
The story thus far…..
I bought an engine for my 1988 Ford F-150 truck. I tore down the engine to check the components, to see what their condition was.
Work done to engine upon tear down:
1 New Piston
New Cam & Lifters
All new Gaskets
Bearings were lightly worn, but otherwise okay
Water Pump
Thermostat
During run-in, I found what sounded like a single valve clattering during acceleration (goes away in cruise). Could not isolate and is not a major concern AT THIS POINT.
After about 5K miles (mostly city driving), I get a lopey idle (NOT a miss). It takes forever to warm up (suspecting stuck thermostat). Once warm, drives okay. Oil pressure will drop to ZERO (like a wire had been cut) when stopping or anywhere below 1K RPM’s and the engine dies. In order to restart, it takes a bit of cranking, but dies if not kept at 1500RPM or higher. Sometimes it will die in a turn after a short coast. I have no problems on the highway.
Just for giggles, I put a vacuum gauge on it and it shows 22ish and fairly steady at idle, which is odd, considering the lope. Fuel pressures (pre-start and running) are within limits (I don’t recall the numbers at the moment, but they were acceptable when I checked them).
NEW PARTS INSTALLED
*Fuel Pump
*Fuel Pressure Regulator
*Fuel Filter
*Injectors
*IAC
*Coil
*Wires
*Cap
*Rotor
*TPS
*Coolant Temp Sensor (to computer)
TRIED
*Sniffed for vacuum leaks & found none (used ether). It actually idles better with the brake booster vacuum line disconnected.
*Changed computer and discovered no change in behavior of the truck.
*Looked for bad grounds, found 1, fixed that and saw no change.
WHAT AM I MISSING HERE?
I bought an engine for my 1988 Ford F-150 truck. I tore down the engine to check the components, to see what their condition was.
Work done to engine upon tear down:
1 New Piston
New Cam & Lifters
All new Gaskets
Bearings were lightly worn, but otherwise okay
Water Pump
Thermostat
During run-in, I found what sounded like a single valve clattering during acceleration (goes away in cruise). Could not isolate and is not a major concern AT THIS POINT.
After about 5K miles (mostly city driving), I get a lopey idle (NOT a miss). It takes forever to warm up (suspecting stuck thermostat). Once warm, drives okay. Oil pressure will drop to ZERO (like a wire had been cut) when stopping or anywhere below 1K RPM’s and the engine dies. In order to restart, it takes a bit of cranking, but dies if not kept at 1500RPM or higher. Sometimes it will die in a turn after a short coast. I have no problems on the highway.
Just for giggles, I put a vacuum gauge on it and it shows 22ish and fairly steady at idle, which is odd, considering the lope. Fuel pressures (pre-start and running) are within limits (I don’t recall the numbers at the moment, but they were acceptable when I checked them).
NEW PARTS INSTALLED
*Fuel Pump
*Fuel Pressure Regulator
*Fuel Filter
*Injectors
*IAC
*Coil
*Wires
*Cap
*Rotor
*TPS
*Coolant Temp Sensor (to computer)
TRIED
*Sniffed for vacuum leaks & found none (used ether). It actually idles better with the brake booster vacuum line disconnected.
*Changed computer and discovered no change in behavior of the truck.
*Looked for bad grounds, found 1, fixed that and saw no change.
WHAT AM I MISSING HERE?
04-18-2015, 08:40 AM
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I have to say, this is fascinating. 112 people have looked at this post and NOT ONE person has ANY IDEAS? A Ford F150 forum? No ideas at all? This problem cannot be that unique, it can't be.
I am assuming that I am missing the obvious, which isn't unrealistic. But no one has any ideas?
Fascinating.
I am assuming that I am missing the obvious, which isn't unrealistic. But no one has any ideas?
Fascinating.
04-18-2015, 09:06 PM
#3
Hi. Just finished messing with a Pontiac for several weeks. My first thought is that if the car idles better with the brake booster disconnected, could the booster itself have a leak. I know the vacuum test says otherwise, but that fact is curious. Could it be leaking only when the brakes are applied?
Last edited by Chris80648; 04-18-2015 at 09:10 PM. Reason: second thought
04-20-2015, 10:12 PM
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The more I think about it, the more I am leaning to some bad wiring. Some of the things just don't make sense. I know it doesn't take much corrosion on wiring to wreak havoc in an electrical system. Just wish I knew where to get the connectors to rebuild the engine harness. But why does this start happening AFTER the engine warms up? If I start up and drive immediately It has NO problems, 'till it gets warm.
04-23-2015, 03:51 PM
#7
What's the fuel pressure look like when it's acting up?