Finally found the problem with the truck engine....

As many of you know, I have been fighting a starting problem on the 641 in the truck. I took the truck to US43 two years ago for the Ford race and it wouldn't start and ending up breaking the starter and flexplate. I pretty much lost interest and focused on work and another project for a while. This summer, I decided it was time to get it going and bought a new Meziere starter and ATI flexplate.

    I got it all ready to go two weeks ago and tried to start it. The starter sounded good, but it still wouldn't start most of the time. Sometimes it would, then sometimes it wouldn't. When it did, it took 4-5 seconds to sync up and start firing, which seems like forever. I had a feeling it was pulling the voltage down too low while starting. The battery would go from 17 down to 11.5 while cranking. Upon advice from Chuck Ford, I took the two 12v batteries out of my F250 and connected them in series to the starter only for 24v. I let the 16v battery run everything else.
I primed the fuel system, gave it a shot of gas, and it fired right up like it's supposed to within 1 second. I tried it several times and started up and ran perfect.
Now I just have to get some good batteries in here and do a little re-wiring and I should be able to get the truck ready to go. I'll get a video up soon if I can figure out how to make it a smaller file.

Good to hear you got the problem solved! Your truck has a lot more electronics than my car but the rock 16v battery has been great for me.maybe 2 of them would work for you.

If I go the conventional route, Rock is what I'll buy. I am for sure going to run the MFI on a RC LIPO battery. I'll probably end up with a Rock 16, but if I can get two lightweight 12v batteries, I'm going the 24v route.

That's great news to hear that you found the problem and have a cure. I can't wait to see it haul it down the track man!!

I'm going to start it and do a burnout this weekend in front of the house, lol.

Something sounds funny that it takes 24 volts to turn over an engine thats not pushing some huge blower. Not bashing your success.... but what is the wiring of the ground of the engine/starter to the battery?
I have a gear reduction starter that's far from anything extravagant and it turns over 18-1 525 cu in with a normal auto zone 65 series battery...

Kim, it will turn over at 12, 16, or 24v fine. The MFI computer doesn't like the voltage drop and it causes the modules to re-boot. This re-boot takes 4-5 seconds or sometimes not at all. The main thing is to run a separate battery for the MFI. I will probably stay 16v start with another small battery of some sort on the MFI. The MFI fires the 8 injectors and 8 coils. The coils may be voltage-sensitive also, because the injectors usually always fire.

Also, the wiring consists of a #1 copper positive and negative cable running from the battery in the back to the firewall feed-through junction block. On the engine side, the positive goes to the starter and the negative goes to the pass side cylinder head and then over to the driver's side head with a smaller wire.

David Willingham wrote:Kim, it will turn over at 12, 16, or 24v fine. The MFI computer doesn't like the voltage drop and it causes the modules to re-boot. This re-boot takes 4-5 seconds or sometimes not at all. The main thing is to run a separate battery for the MFI. I will probably stay 16v start with another small battery of some sort on the MFI. The MFI fires the 8 injectors and 8 coils. The coils may be voltage-sensitive also, because the injectors usually always fire.

Im often two steps behind...........  Even with a 150 amp or 200 amp draw from a starter, I would suspect a bad battery in itself if its dropping below 12.5 volts for the seconds of cranking.  But If it takes a dedicated battery for the computer side........ not too painful, helps balance weight...

Why not run two strands of 1 gauge from head to chasis.... and from battery ground to chasis and use the whole chasis as your ground conduit. Works on the mudstain fine.

The battery could be bad. It's a XS power 1600, 30 lb deal. It pegs a 400 amp inductive meter while starting. The reason for using a negative wire was from the electrical engineer that designed the MFI. Something about a "loop" and "fields" and "interference" and some other things I know nothing about, lol.

Did you get your shop floor fixed?

Dave C., are you asking me?

David Willingham wrote:Kim, it will turn over at 12, 16, or 24v fine. The MFI computer doesn't like the voltage drop and it causes the modules to re-boot. This re-boot takes 4-5 seconds or sometimes not at all. The main thing is to run a separate battery for the MFI. I will probably stay 16v start with another small battery of some sort on the MFI. The MFI fires the 8 injectors and 8 coils. The coils may be voltage-sensitive also, because the injectors usually always fire.

Have to love CPU technology .1V too little =0 participation , I agree the dedicated battery for the MFI if you know the voltage no-go point you could also wire in a warning light for the heads up on the circuit of the dedicated battery, maybe power something else (non compulsary for running- EG: Lights etc) on the dedicated MFI battery that you can toggle off in case of the warning light comes on in order to give additional output to the MFI and make the round.

Good idea. The MFI computer can do all that. It has "events". I can tell it to output at a certain battery voltage if I wish. I going to try some RC batteries used on the Hexacopters for power. Shane Stack is using two on his car, so the MFI designer is recommending 3, possibly 4 on mine. They are a lot cheaper than the lithium batteries they're are selling for motorsports applications. They are $125 each plus $300 for the charger. Best part is they weigh 3 lbs each.

Does the engine have any form of a short length dedicated chassis ground (other than the motor/mid plates)? Something like either a cable/strap running from say one of the mid plate's chassis mount bolts to a block bolt or a starter mounting bolt? Or mild steel/moly for-aft travel limiters?

I once worked on a full chassis car with aluminum motor/mid plates that would crank real slow if you tried to start it without it's steel travel limiters installed. I guess the steel limiters made a better ground path to the chassis than the aluminum plates did.

Cranked it up yesterday on the original 16v and a 12v battery powering the mfi. Ran fine. I went to the hoppy shop today and bought a 14.8v, 4 cell LIPO battery for the mfi. I'm gonna drive it tomorrow.

How did it run

It did great! Tons of power. I still have things to fix before I go to the track. I want to make sure it's not going to try to kill me before I go. Going to get Chuck Ford to give the truck a good inspection and setup before I go to the track.

Good deal

I bet it felt nice to drive it again! When you get a chance,post up some video.

David it is a cool deal for sure. Look forward to seeing it out.

Awesome! Can't wait to see it run.............

David Willingham wrote:It did great! Tons of power. I still have things to fix before I go to the track. I want to make sure it's not going to try to kill me before I go. Going to get Chuck Ford to give the truck a good inspection and setup before I go to the track.

Sweet, Let us know when it hits the track!

It's probably going to be sooner than later. I wasn't in a hurry to run it, but now I'm getting tired of worrying about if it's going to run straight, can I handle it or does it look good enough to go to the track without bodywork, etc. I think I'm going to put the roll bar padding in, borrow a trailer, and go see what happens in the next few weeks.

Hell Yeah! Let 'er EAT!