Ferdy Mint
Full Access Member
This post really hit me because 1) we like Fords and 2) all our trucks are Fords, but FURD REALLY SCREWWS UP SOMETIMES.
You should really read the FTE thread, it's long but good stuff. I'll summarize. Ford put a little alternator in the SD 7.3 to protect the GPs, which were not engineered to run after the motor starts up. Beru designed the GPs to run on 11 volts, which is what you'd get when cranking with good batteries. The GPs are actually rated for 11V, not more. Then Ford in its corporate wisdom decided to have the PCM keep the GPs running long after the motor starts, to pass EPA standards. On my 2000 I see the GPR holding on for about 30 seconds after a cold start, which is useless to me. Ford even runs the GPs when you let off the throttle. And all that is for emissions crapola, don't get me started.
The alternator on an SD is only 110 amps, and I always wondered why. An OBS 7.3 gets 130 amps, and in general has less electrical stuff running, its fuel pump is mechanical for example. So why did Ford put in such a small alternator in the SD? It's because the GPs were not built to run after the motor starts up, so they are sitting there in the combustion chamber, diesel firing off around them, the alternator is spinning, and they are still heating from the PCM running the GPR. That was all Ford's decision. So they get too hot, which shortens their life. The small alternator keeps the running voltage down under 12. Mine hovers around 11.5 or so with a good alternator I put in last winter.
What a rotten decision, when Ford could have put in a newer Beru GP like the 6.0 got, that will not be damaged by running after the motor starts. It's one of those face palm moments when you learn.
The easy solution is to put the GPR ground wire on a switch in your cab. Keep it off most of the time unless the weather is cold, and switch it off as soon as the motor fires up. Or you can just use a springy push button that you have to hold to fire the GPs. We run that already on IDIs to prolong GP life, some of our IDIs use 6v GPs.
Once you put manual control on the GPR ground, then you can install a bigger alternator. 160 amps sounds about right to me. Especially if you have extra upfit equipment on your truck, a big stereo or CB amp, lighting, winch, whatever.
Here is the FTE post. https://www.ford-trucks.com/forums/...t-glow-plugs-hope-you-guys-can-get-along.html
You should really read the FTE thread, it's long but good stuff. I'll summarize. Ford put a little alternator in the SD 7.3 to protect the GPs, which were not engineered to run after the motor starts up. Beru designed the GPs to run on 11 volts, which is what you'd get when cranking with good batteries. The GPs are actually rated for 11V, not more. Then Ford in its corporate wisdom decided to have the PCM keep the GPs running long after the motor starts, to pass EPA standards. On my 2000 I see the GPR holding on for about 30 seconds after a cold start, which is useless to me. Ford even runs the GPs when you let off the throttle. And all that is for emissions crapola, don't get me started.
The alternator on an SD is only 110 amps, and I always wondered why. An OBS 7.3 gets 130 amps, and in general has less electrical stuff running, its fuel pump is mechanical for example. So why did Ford put in such a small alternator in the SD? It's because the GPs were not built to run after the motor starts up, so they are sitting there in the combustion chamber, diesel firing off around them, the alternator is spinning, and they are still heating from the PCM running the GPR. That was all Ford's decision. So they get too hot, which shortens their life. The small alternator keeps the running voltage down under 12. Mine hovers around 11.5 or so with a good alternator I put in last winter.
What a rotten decision, when Ford could have put in a newer Beru GP like the 6.0 got, that will not be damaged by running after the motor starts. It's one of those face palm moments when you learn.
The easy solution is to put the GPR ground wire on a switch in your cab. Keep it off most of the time unless the weather is cold, and switch it off as soon as the motor fires up. Or you can just use a springy push button that you have to hold to fire the GPs. We run that already on IDIs to prolong GP life, some of our IDIs use 6v GPs.
Once you put manual control on the GPR ground, then you can install a bigger alternator. 160 amps sounds about right to me. Especially if you have extra upfit equipment on your truck, a big stereo or CB amp, lighting, winch, whatever.
Here is the FTE post. https://www.ford-trucks.com/forums/...t-glow-plugs-hope-you-guys-can-get-along.html