sgtsandman
Automotive Technician
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- 2019
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- Ford Ranger
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- 4WD
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- 265/70R17
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- Anything that can go wrong, will go wrong. Plan for it as best you can.
Ok, some updates on the truck. For those who don't know, the truck has been having some issues with not starting when hot. Part of the issue was the fuel pump as mentioned above. I unloaded the parts cannon on it after doing some troubleshooting and not being able to pin point a problem. Being that it only happens when it's hot in the engine bay, makes troubleshooting difficult, not only from the heat but keeping the part(s) that may be at fault hot enough to narrow down the problem.
Since the question may be asked, how do I know what the engine bay temperatures are. I have a Scanguage II that is hooked up to the OBD II port at all times to show intake air temperature, engine water temperature, volts, and average mpg. The intake air temperature is a general gauge in how hot the engine bay is. Yes, it gets diluted by cold air being drawn in from the air filter box but as temperatures rise, it heats up the hose running from the filter box to the throttle body and the intake manifold it self heats up. Somewhere in all that (I think in the hose) is the temperature sensor for the intake air.
Relays were checked, fuel pressure was checked, the ignition coil, IAC and so on. Nothing indicated a problem. So, after doing an internet search on the issue, I came up with a list of parts that potentially could be the issue and threw them all at them. Then tried to simulate that issue by driving the truck for a while to get it hot and bring it back home to see if the issue was fixed so I would not end up with another $200 towing bill and hours of my time wasted in waiting for the tow (on a Sunday of a holiday weekend no less) and for a ride home. The issue appeared to be fixed. The truck would start up just fine after getting home and after waiting a while for engine bay temperatures to rise due to just sitting with no air flow. So, it appeared that the issue was fixed.
I was incorrect. The issue was better, but not fixed. A clue, that I missed earlier, was that in stop and go traffic, when the engine bay temperatures would climb, the air conditioning would go out until I was able to get out of traffic and get the engine bay heat purged. So, I looked at the relays again. While troubleshooting, they cooled down enough with the hood open and the cover off the power distribution block that the truck would start up again and run just fine. That happened more than once. So, the relays are the problem. There are three identical relays in the power distribution block that power the fog lights, air conditioner, and the fuel pump.
Relays 46A, and 48A and 48B are the offending relays (See the attached PDF). Also not that since all three relays are the same age, switching them around did not fix the issue.
No one other than Ford dealers sell the the Motorcraft relays, and at about $30 a piece, I decided to gamble on aftermarket replays to fix the problem. They did not, they made it worse. The A/C would cut off even sooner (lower engine bay temperature) than the failing OEM ones currently do and the crank, not start happens even sooner. The side benefit is that I now have relays I can swap out when it happens and get going again.
So, I broke down and spent the $90+ on the three relays and I'm waiting from them to be delivered since my work hours are not friendly with dealership hours.
Why all three instead of just the fuel pump/fuel injector relay you may ask? I like A/C and the fog lights are real handy early in the morning on the back roads I commute to and from work on.
EDIT: For those who may be running into the same issue, the original relay part number is 9L2T-14B192-AA. The new relay part number is 5M5Z-14N089-AA. Both are four pin relays. You do not want the other one listed that has five pins.
Since the question may be asked, how do I know what the engine bay temperatures are. I have a Scanguage II that is hooked up to the OBD II port at all times to show intake air temperature, engine water temperature, volts, and average mpg. The intake air temperature is a general gauge in how hot the engine bay is. Yes, it gets diluted by cold air being drawn in from the air filter box but as temperatures rise, it heats up the hose running from the filter box to the throttle body and the intake manifold it self heats up. Somewhere in all that (I think in the hose) is the temperature sensor for the intake air.
Relays were checked, fuel pressure was checked, the ignition coil, IAC and so on. Nothing indicated a problem. So, after doing an internet search on the issue, I came up with a list of parts that potentially could be the issue and threw them all at them. Then tried to simulate that issue by driving the truck for a while to get it hot and bring it back home to see if the issue was fixed so I would not end up with another $200 towing bill and hours of my time wasted in waiting for the tow (on a Sunday of a holiday weekend no less) and for a ride home. The issue appeared to be fixed. The truck would start up just fine after getting home and after waiting a while for engine bay temperatures to rise due to just sitting with no air flow. So, it appeared that the issue was fixed.
I was incorrect. The issue was better, but not fixed. A clue, that I missed earlier, was that in stop and go traffic, when the engine bay temperatures would climb, the air conditioning would go out until I was able to get out of traffic and get the engine bay heat purged. So, I looked at the relays again. While troubleshooting, they cooled down enough with the hood open and the cover off the power distribution block that the truck would start up again and run just fine. That happened more than once. So, the relays are the problem. There are three identical relays in the power distribution block that power the fog lights, air conditioner, and the fuel pump.
Relays 46A, and 48A and 48B are the offending relays (See the attached PDF). Also not that since all three relays are the same age, switching them around did not fix the issue.
No one other than Ford dealers sell the the Motorcraft relays, and at about $30 a piece, I decided to gamble on aftermarket replays to fix the problem. They did not, they made it worse. The A/C would cut off even sooner (lower engine bay temperature) than the failing OEM ones currently do and the crank, not start happens even sooner. The side benefit is that I now have relays I can swap out when it happens and get going again.
So, I broke down and spent the $90+ on the three relays and I'm waiting from them to be delivered since my work hours are not friendly with dealership hours.
Why all three instead of just the fuel pump/fuel injector relay you may ask? I like A/C and the fog lights are real handy early in the morning on the back roads I commute to and from work on.
EDIT: For those who may be running into the same issue, the original relay part number is 9L2T-14B192-AA. The new relay part number is 5M5Z-14N089-AA. Both are four pin relays. You do not want the other one listed that has five pins.
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