So My Truck Died Today...

[ZedMikey]

... as I was cruising down I-5. '92 automatic.

Cruise control set, and humming along... then it just dies. I didn't notice any stumbling or anything... just dead. I have been fortunate that I haven't had to do any major work on the truck since I got it 5 months ago, but that also means I don't really know what makes it tick, yet. Or in this case... what makes it NOT tick.

As our Cummins are mechanical, there isn't much that can go wrong to make it die and not start. From dinking around with it this evening, I am pretty sure it is a fuel delivery issue. I loosened the line to the #1 injector and turned it over and got some fuel, but no where near what I'd expect for this motor.

How 'bout a quick overview of the fuel delivery system? I know the injection pump feeds the injectors themselves and handles the timing of the system. Is there an electrical fuel pump in the tank that feeds the IP? The wiring under the hood is kinda scary... are there any electrical bits that would cause this? The shutoff solenoid could, of course. I assume it shuts off fuel flow unless it gets power, right?

Anything else I should be aware of before digging in... without a service manual? Thanks!

 

[GIT-R-DONE]

I would change the fuel filter first. Could be the fuel pump, but its on the side of the motor about 5:00 from the fuel filter. To my knowledge, there wasnt an in-tank pump for these trucks (first gens) Shut off solonoid is hard to get to, but can be done with the proper tools.

 

[OKish]

there are 2 solenoids they both should have power with key on, make sure one connector didnt pop off.

 

[ZedMikey]

there are 2 solenoids they both should have power with key on, make sure one connector didnt pop off.

Do you have any pics of said solenoids? I'm pretty sure I know which ones you are referencing, but I'd like to be sure. One is below the IP and to the front, the other (the shutoff solenoid, yes?) is on the back of the IP. Should they both be getting 12V with the key on? The shutoff solenoid has two connectors, doesn't it?

Anybody have an engine wiring diagram they could link me to? That would solve a lot of the electrical woes in the engine compartment, I think.

 

[pepecat]

the KSB valve, and the Fuel Shutoff Solenoid. If the Connector for the Fuel Shutoff solenoid comes off, You'll get the exact result you describe. It happened to me on the freeway. I just had to reconnect the wire on the IP and off I went.

 

[jimnance]

Had the same thing happen with my old first gen. The fuel cutoff solenoid is spring loaded to go to the closed position if it fails to receive electrical power. In my case the fuse had blown for unexplained reasons. Easy to check. Locate the solenoid on the drivers side of the engine. You should see a fuel line leading to it from the filter. When the ignition is turned to the "on" position the solenoid should open to allow fuel to flow. Try moving it by hand first to see if it moves freely, then see if it lifts fully with the key on. If not, you've located the problem. Check the fuse, if it's OK check to see if the the current is getting to the solenoid, if so, the solenoid will likely need to be replaced.



A plugged filter is a possible culprit, but you would probably see a more gradual loss in power as flow was restricted.

 

[Cummins360]

What is the other solenoid for??? KSB???

 

[ZedMikey]

A plugged filter is a possible culprit, but you would probably see a more gradual loss in power as flow was restricted.

That was my guess on the fuel filter, too.

I will definitely check the function of the FSS.

Cummins360 has a good question... what does the KSB valve do?

 

[Grey Wolf]

The KSB is for cold starts, it helps reduce smoke and improves the idle. It will shut off after a set point in temp is met. .

 

[ZedMikey]

The KSB is for cold starts, it helps reduce smoke and improves the idle. It will shut off after a set point in temp is met. .

So I can rule this one out as to causing my problems then, correct? It sounds like the truck should function whether the KSB valve is working properly or not.

 

[ZedMikey]

I took another look at the truck this morning, with comments from here in mind. Now I have more questions.

Wiring: Ok, I've got the TPS plug with three wires (purple w/white, black w/blue and orange w/black, IIRC), then I have three single wire connections, one black wire at the KSB valve (below and to the front of the IP), another black to the FSS (on the back of the IP above the outlets to the injectors), and a dark blue plugged in at same location on the FSS. WIth the key on, I get no voltage at any of the three single connections. The odd thing is the two black wires are plugged into the air temp switch... and nothing else connects those wires to anything. Of course there is no voltage there. The plug on the air temp switch looks like it should have a third wire, but there's nothing there. Am I missing something? Or is the dark blue wire supposed to provide voltage to the FSS and the black wire from the FSS to the ATS provides power to the ATS which supplies power to the KSB based on the air temp via the other black wire? That seems a mighty convoluted way to do things...

FSS: There is only one part on the back of the IP that moves, so I assume that is the actual plunger for the FSS. By hand, I could only get it to move about 1/8". Is that normal? Also, it didn't budge with the ignition on... but nothing appears to be getting any voltage, so of course it won't budge.

Fuses: Another part about this truck that seems kinda weird. I've just got random fuses strewn about the driver's side of the engine compartment. No fuse block that I have found, just inline fuses wired into the relay wiring. Is there a fuse block somewhere that I am not seeing?

Wow... long post... thanks again for all the help, guys!

 

[pepecat]

So you're not getting any power with the ignition turned on, but the starter turns the engine over, right?

 

[jimnance]

I wish I could remember where that fuse was. I was in a fuse block I wasn't familar with and I recall having difficulty tracking it down. This was fifteen years ago... ... .

 

[ZedMikey]

So you're not getting any power with the ignition turned on, but the starter turns the engine over, right?

Oh yeah, starter works like a champ. I'm not THAT clueless about the truck. Thanks for double checking the obvious, though.

 

[rlyons]

The fuse block should be directly above your brake pedal? If you are getting no power to the wires on the FSS then it is not going to run. May be a fuse link also but I am not shure which one. Could also be the ignition switch failed as these do at times. Feed power directly from the positive battery cable to the FSS and see if it runs.

 

[dpuckett]

I believe jimnance may be referring to the 2nd gen trucks and a fuse block under the hood.



ZedMikey- if you are getting no power to the blue wire, chances are you have blown a fusible link on the driver's fender well. The color and where it goes to is not in my memory right now, but I will try to look up in my book which color wires go where and report back later.



KSB function- power from the blue wire energizes the black wire that goes up to the thermo switch up on top of the intake. When it is cold, the thermo switch sends power to the KSB, which advances the timing a little to cut white smoke. ONce ti reaches a certain temp, the thermo switch cuts out, de activating the KSB.



Daniel

 

[TBurow]

now i have a question, dpuckett, do you have a pic of the thermo switch or a wiring diag for the ksb and thermo switch? my engine is a transplant into a 96 that had a v10 so all the factory wires were butchered by the guy i got my engine from. cold season is coming and i would like it to work right. thanks

 

[ZedMikey]

Ah! Thanks, Daniel! So that convoluted way IS the way it works... strange. I will jump the FSS to the battery and see what happens... tomorrow.

 

[dpuckett]

TBurow- Sorry, I dont have the diagram on this computer nor a scanner, but it is simple- wire runs from the shut off solenoid up to the thermo switch (behind the intake heaters), and then back down to the KSB. If you wanted, you could run the wiring to a switch in the cab, but you'd have to pay attention and turn it off when it got warmed up. As a bonus, though (and this was from Harry at PDR) you could also use the switch to give a little timing bump for playing with rice burners at stoplights



-DP

 

[ZedMikey]

So, the good news is that jumping the FSS worked. It started up just fine. I then pulled the wire and expected it to die... and it didn't. Shut off with the key, though. I guess the connection was a little iffy and when I pulled it and reseated it... well... it works now!