Good evening fellow Ford friends. I have a 79 f150 4x4 ranger with a 400m motor and love my truck. Coming home from camping trip this weekend she died twice on the freeway. I had here towed home. When I looked under hood I saw some smoke coming from back of motor. I thought maybe bad egr valve. Today after removing egr valve I notice this part -picture attached, does anyone know what it is?

sorry about double post as I missed the ranger topic and posted in general.

thanks for any input

 

The single wire bell looking part?

Is the oil pressure sender....

 

Yes, is that the oil sender unit? If so, I do not believe it is my problem. The reason I have focused on that area was because when truck died I saw some smoke come from that area. I have cleaned egr valve - it wasn't that dirty so I am back on hunt for why truck dies under load - accelerating....

 

Yes it’s the oil sending unit..

EGR may fail the diaphragm side causing a small vacuum leak, or the valve may hang if carboned and cause poor unstable idle conditions and sometimes mid range performance issues, but most times they fail with no real impact.

How much smoke? Oil burning off?, coolant or ?

Two thing you want to rule or prove out is fuel delivery and a healthy spark. Does it restart after the engine cools a bit? Yes..Ignition modules had a history of failing heated then restart after a cooling soak. The pickup coil in the distributor had fail potential too. Ignition module would be suspect first, and can be tested prior to a new unit.

Fuel delivery, or loss of,, more so at ‘high demands’ like you mention can stall the engine, but usually a filter restriction, tank pickup etc will get you a flat throttle at high RPM and loads/speeds.. Fuel pump failing for volume and PSI can be similar, failed would stall the engine, with/without a restart.

If it stalls, don’t try and crank the engine,, remove the air cleaner and pump the throttle lever looking into the carb. Any accelerator pump squirt visible?
If yes,, if you have a spare spark plug or a tester, helper etc, check for a healthy spark being delivered from the coil high tension wire at the cap to ground. Good hot spark?

 

Thank you for the very useful info. I am leaning towards no spark as the carb and fuel pump were done a few months ago. I am going to replace ignition coil as it is the same coil that was there 8 years ago when I got truck. Thank you again.

 

Proving out the possibilities is always a good bet before replacing any parts, older coils rarely fail..

Checking the carb for fuel spray is easy enough, and don't rule out a new part failure even if partial. More so in older rigs if fuel rust/debris/water etc is/was a concern. Even though the carb and pump are replacements, doesn't mean there's not a restriction in the tank, or the new pump is having issues.. If the carb sprays, then the bowl/s are filled and are generally not the cause of the stall.
Ignition modules of the day failed at a fairly high rate.. Way more than a coil. As mentioned,, modules liked to fail heated, then may restart after some cooling time.. But not always..