6.9 dies suddenly, then starts up shortly thereafter

[RenoHuskerDu]

Howdy, our Bullnose 420cid diesel is in pretty good shape. ZF5 conversion. The injection pump (IP) was rebuilt 30k ago. Fuel filter OK. Ignition switch 2 years old. It's a daily driver now for one of my sons while he builds up his Bricknose dually.

Today she died three times while driving at low speeds. Both times she started right back up. The third time he had to wait a few minutes, by the side of the road. He made it to his destination (volunteer fireman) while I was on my way there. We swapped trucks, my other son drove the Bullnose home, and she had full power, didn't act up at all.

These aren't symptoms of a clogged fuel filter, but I ordered a few spares anyway. The only thing I can think of that could cause this on a diesel IDI is the ignition switch, which is new, or the fuel cutoff solenoid on the IP. I'm leaning for the latter. Tommorow in the light he'll inspect its wiring.

I looked for that solenoid on Rock Auto but no go. We do have a good NAPA nearby and I'll check its price tomorrow. If it's less than $50 I'll just put one in, unless we spy an obvious wiring issue tomorrow. I think we'll try a jumper from 12v to that solenoid as a test workaround.

 

[grumpin]

The only other thing that pops into my mind is that it’s getting air in the system somewhere.

Like the fuel filter.

Or the IP, even though it’s rebuilt.

 

[myrl883]

The only other thing that pops into my mind is that it’s getting air in the system somewhere.

Like the fuel filter.

Or the IP, even though it’s rebuilt.

If it's getting air, it won't "start right back up". It'll take lotsa cranking time. Low speed stalling or stalling when you take your foot off of the accelerator quickly is the first sign of a failing pump - especially if it runs well under load.

[RenoHuskerDu]

If it's getting air, it won't "start right back up". It'll take lotsa cranking time. Low speed stalling or stalling when you take your foot off of the accelerator quickly is the first sign of a failing pump - especially if it runs well under load.

The FSS has a solid 12v and its terminals are now cleaned and copper buttered. But it doesn't have a distinct click when I touch the terminals. Almost a buzzing, and every 6th time or so it's silent.

I think my FSS is dying. I hope Accurate Diesel has them, because NAPA doesn't and I dislike the Furd Stealer. IH is a mess these days when you want parts for any motor that isn't in a tractor. "Oh no, you have to call Fred at Case in Kalamazoo, he can help you...." Then Fred says "What? A pickup truck? We only have tractor parts." and so on.

Update: Accurate Diesel has that solenoid in stock for $59. Tim and his crew are lifesavers for IDI stuff.

[86 12 Brutus]

The FSS has a solid 12v and its terminals are now cleaned and copper buttered. But it doesn't have a distinct click when I touch the terminals. Almost a buzzing, and every 6th time or so it's silent.

I think my FSS is dying. I hope Accurate Diesel has them, because NAPA doesn't and I dislike the Furd Stealer. IH is a mess these days when you want parts for any motor that isn't in a tractor. "Oh no, you have to call Fred at Case in Kalamazoo, he can help you...." Then Fred says "What? A pickup truck? We only have tractor parts." and so on.

Update: Accurate Diesel has that solenoid in stock for $59. Tim and his crew are lifesavers for IDI stuff.

I dont know anything about disel engines, but this sounds to me like classic ignition module problem especially if you have the tfi module. Just throwing that out there, it happened to me and it was then we decided to relocate the module to the fender wall.

[old55pete]

I dont know anything about disel engines, but this sounds to me like classic ignition module problem especially if you have the tfi module. Just throwing that out there, it happened to me and it was then we decided to relocate the module to the fender wall.

George, a 6.9 IDI diesel dosent have a distrubiter, or for that matter an ignition system. Some folks look at the injection pump and think it is a distrubiter because of the 8 fuel lines to the injectors, but in fact all they do is carry fuel.

[Ford F834]

The FSS has a solid 12v and its terminals are now cleaned and copper buttered. But it doesn't have a distinct click when I touch the terminals. Almost a buzzing, and every 6th time or so it's silent.

I think my FSS is dying. I hope Accurate Diesel has them, because NAPA doesn't and I dislike the Furd Stealer. IH is a mess these days when you want parts for any motor that isn't in a tractor. "Oh no, you have to call Fred at Case in Kalamazoo, he can help you...." Then Fred says "What? A pickup truck? We only have tractor parts." and so on.

Update: Accurate Diesel has that solenoid in stock for $59. Tim and his crew are lifesavers for IDI stuff.

If you don’t hear a crisp ‘click’ when you touch power to the FSS then that is probably your culprit. Air intrusion would be accompanied by running rough and surging while driving. The other thing that can/will cause stalling (and immediate re start) is an obstructed fuel return line. Back pressure retards the IP timing to the stall point. You will notice the diesel clatter getting quieter and quieter and power falling off until it stalls. To test, you can disconnect the return line by the firewall and run it into a bottle and see if the problem goes away. I once drove several miles home like this, pulling over every so often to empty the bottle.

[86 12 Brutus]

George, a 6.9 IDI diesel dosent have a distrubiter, or for that matter an ignition system. Some folks look at the injection pump and think it is a distrubiter because of the 8 fuel lines to the injectors, but in fact all they do is carry fuel.

Steve, i wasn't sure, i know nothing whatsoever about a disel engine, just though i'd throw it out there

[RenoHuskerDu]

Steve, i wasn't sure, i know nothing whatsoever about a disel engine, just though i'd throw it out there

Update: We installed the new FSS and clearly the old one was on its last legs. Nice crisp click now on actuation.

But now we're having trouble getting her restarted. 3 injector lines cracked and we're still getting splatters of air after cranking for long enough for my eldest the FT wrench to say 'stop, the starter's new'

Now she's charging up overnight, tomorrow we're going to eliminate the water separator on the upper driver side of the firewall. It looks as old as Moses and I hear tell that it can be a source of big air in the fuel.

She sure acts like air in the fuel.

My other son just joined the forum, he drives this Bullnose daily, and I told him to read this thread and bone up on the water separator issue. Our newer IDIs don't have one, and from what I remember they are nothing but trouble.

[Minty Ferd]

Update: We installed the new FSS and clearly the old one was on its last legs. Nice crisp click now on actuation.

But now we're having trouble getting her restarted. 3 injector lines cracked and we're still getting splatters of air after cranking for long enough for my eldest the FT wrench to say 'stop, the starter's new'

Now she's charging up overnight, tomorrow we're going to eliminate the water separator on the upper driver side of the firewall. It looks as old as Moses and I hear tell that it can be a source of big air in the fuel.

She sure acts like air in the fuel.

My other son just joined the forum, he drives this Bullnose daily, and I told him to read this thread and bone up on the water separator issue. Our newer IDIs don't have one, and from what I remember they are nothing but trouble.

Howdy,

I'm RenoHuskerDu's son, tomorrow I will rip out the water separator and replace it with some fuel line. We'll see if that fixes the problem, and keep you updated.