I'm working on an old tree service truck for an estate, 1987 Chevy 7000 with an 8.2. Was running when parked several years ago. Starts and runs easily with ether or gas rag, but won't run on its own. It has the newer style electronic governor with no visible shut off solenoid. I think it's pumping fuel because I noticed a small leak in the return line, which I fixed. I took the lid off the governor and inspected the motherboard, but I don't see any signs of shorts or melted spots. I removed the motherboard to access the rods that push the injector rails. I cannot move them manually more than a fraction of an inch, but I don't know exactly how it works so that may be normal. Anyone have any thoughts on diagnostics? Things to check?
I reckon nobody's probably dealt with one these in years. Anybody know a forum where some old timers might hang out?
This is as good as you are going to find, but you probably know that the 8.2 was not much good when new, and hasn't gotten any better with age. Electronic governor on one of these is something I have never even heard of.
I don't know much about detroits, but have you checked the pressure coming off the fuel pump?
I think most guys that knew about them have tried hard to forget! I have a little experience, from what I remember on the mechanical governor to shut it down it moves the rack to a no fuel position which is done with a solenoid that pushes with a spring to shut it down and when energized releases to allow the racks to move. There is also a small lever to shut it down with a pull cable if it doesn't have the solenoid. I have never heard of one with an electronic governor so I have no idea what makes it work. If you pull the valve covers and disconnect the linkage to the rack you can see if each side moves freely. If an injector rack is stuck it could be keeping them all shut off but it seems like it should only be the one injector that is sticking that would be not firing if I recall.
We had one in a service truck years ago. Everybody hated the thing. As I recall the fuel injection pump was mechanical with an electric solenoid to shut it down.
JPV, you mention a stuck injector rack...is that prone to happen after setting a long period of time? The rods controlling the injector rack are on a mechanism under the mother board shown in the pic. Should I be able to manually push these rods? If so, one or both are stuck but I don't know if they are stuck by the rails or by something driving the governor that I can't see under there.
This is weird. I've owned three 8.2L powered service trucks (newest was an '86) and have never seen this. An add on from the bucket boom manufacturer for throttle control? Or possibly some last gasp at a DDEC style control from Detroit Diesel? But that is throttle linkage, right? And "parked several years" leads me to think stuck injector rack too. I see this all the time on the 2 stroke engines that sit for a few years.
I would guess it would be an injector sticking like Rzucker says, they are basically the same injectors as the 2 strokes.However I am thinking that if there is a shutoff solenoid that isn't working properly you wouldn't be able to move the rods as it holds the racks in the no fuel position. Even with that gizmo it is still a mechanically injected engine so there must be something that pushes or pulls the racks when you shut the key off. You have the key on when trying this and have checked all fuses? If you were to check the racks by disconnecting the linkage under the valve cover and making sure they move freely that is probably the best way to narrow it down. If someone asked me to trouble shoot one and I saw that thing in the picture I don't know for sure what I would do!
Yes, that computer board is controlling the throttle and had to be added there by the bucket lift manufacturer or whatever attachment is on that bed of the truck. God I hated that Fuel Pincher just slightly more than the 3208 Cat engine. Eye burning and nose stinging sum beaches. That fuel solenoid was a common problem on them, but I would agree that the rack is probably stuck after sitting.
It seems like the fuel shutoff solenoid made a pretty loud click when energized, if you don't hear anything when turning the key on it is probably not working. It should be sticking out the back of the governor, I don't remember how it is removed.
IIRC, it should be a screw/bolt on each side of the solenoid. They were energize to run so yes it should retract with the key on.
I can now see why they had an electronic governor. Probably not to do with driving but to do with working with the bucket up. The stock governor would not hold at any particular RPM with a light or no load. I learned this with fire trucks. With the pump engaged (load) they would behave. But if you just used the hand throttle to try and get say 1500 RPM to warm it up it would either creep up and run at governed (3300 RPM!) or drift down to slow idle. So for running the hydraulic pump they probably added this contraption.
I'm an expert at encountering weird crap that no one has seen before. It's a finely honed skill that took years to develop. Anyway, I wonder if it was a factory option, because it all looks totally factory with the engine and harness. There is a high idle knob but it is attached directly to the pedal in the cab. The throttle cable goes from the pedal to the arm on the governor, but inside the governor cover there is no mechanical linkage. Instead, there is a potentiometer (like a TPS) so the throttle is totally fly-by-wire. The TPS goes to the circuit board and the circuit board has wires that go down under the mechanism with the rods that push the racks. Form the outside, this governor only has two tiny wires going to it, a ground and a key-on hot, both go directly into the circuit board. I don't think it is a fuse issue because I have 12v at the governor with the key on. However, I don't hear or see anything move...which brings me to the next weird thing, there is no fuel solenoid...at least not in the traditional sense, and certainly nothing matching the pictures of the solenoids on the mechanical governors. Two of the wires that go under the circuit board go way down to a small round object held into the very bottom with a snap ring. Could this be the fuel solenoid? I'm going to take another look at it tomorrow evening. I need to get it running to sell, otherwise it's not going to bring anything. Hopefully, the amount of time I dump into this thing won't negate all my sales commission. I wonder what it would bring over the scales?
According to the Google listings for inf o n the governors there are herds of them around! https://www.google.com/search?q=ele...t+8.2&ie=utf-8&oe=utf-8&client=firefox-b-1-ab
...and I've been to most of those links. Haven't found much useful. The only one exactly like mine (pics from a google image search) are from a post on truckmechanictips.com and there are no replies to his post.
You have to figure out WHY the rack wont move.. Which in most cases means, the valve cover has to come off.. Once the vc is off, you can follow the linkage to "the controller" & disconnect IT.. {whatever is shutting the machine down} THEN you can see if the rack is free.. IF it IS free.. back track.. WHATEVER YOU DO.. DO NOT try to start it without some sort of "shut down plan" in place.!!! Those things will take-off in a heartbeat..{stuck injector} You'll HAVE TO choke off the AIR.. cuz when they start to run away, they run on OIL splash> NOT fuel.. so shutting off the fuel is a waste of time.. A THICK piece of wood is used in most cases.. Good luck & let us know how its going..
I was running out of daylight yesterday, so instead of pulling valve covers I unhooked the rods at the governor to manually move the racks. The driver side moves and is spring loaded in both directions. The passenger side only moves and springs in one direction, so it's possibly stuck. In addition, the governor itself does nothing when the key is turned on or off...doesn't move, doesn't make noise, nothing. It's getting 12v and fuses look good. So you reckon the governor is bad, or some part within it?
I would get the rack moving properly first before doing anything else, there must be a crank sensor of some sort that tells the governor rpm so if it isn't spinning it might not move. If it is trying to move but the stick injector won't let it that could be the whole problem. When you try to start it after getting things freed up make sure to have a good method in place to put cover the intake in case it tries to run away like pump guy said. If you want to know why just watch a few youtube videos of engines running away.
It's not even trying to move that I can see. Just to be sure, I unhooked the rods so they wouldn't interfere with the governor and spun the engine over. Still no movement from the governor.
I can't comment on what you should see in there I guess, I have no idea
I've got one of those engines in an '89 7000 flatbed. Yes, the solenoid clicks hard on mine. Gutless wonder, but it gets less than 2 months usage/year and less than 1000 miles. I'll run it until it dies.
Is it electronic governor or mechanical?
I'm going to be very polite here... GET THE INJECTORS UNSTUCK!. If indeed this is some potentiometer controlled fuel system the injectors are controlled by a stepper motor most likely and all you are doing so far is shortening its life. If the racks wont move, asking a ton of questions that have already been answered is not going to help. I'm going to add here that you are especially lucky that those engines were limiting speed governors that went to shut down as a default. If they were stuck wide open like a Variable speed governor, your engine would now be in orbit.
Ok, racks free. Done. All I'm asking (that hasn't been answered) is should there be key-on noise/movement from the electronic governor like the mechanical one? If so, that's the damn problem.
I reckon it's solved. So given the way it works it obviously *has to* move the racks with either key-on or engine movement which it does not. So I went to test the outputs on the circuit board and it put me in mind of a CDI and how it can arc internally (if you've ever had one apart, it's basically a series of capacitors on a circuit board potted in silicone...very simple for how expensive they are). So on a whim, before I pulled it off I cupped my hands over it (to make it dark) and had my helper spin it over. I can see a spark under the silicone...not every time but about every other key cycle. Appears to be coming from a capacitor about an inch below the red and black input wires. I'm not showing output, so I guess it's shorted. Thanks for all the comments, and for that fella not blowing a gasket even though I had the rack linkage unhooked so wasn't short-living anything except for my back from leaning down in the engine compartment. The truck will probably see the scales...unless I can off load it on one of you guys? LOL
So are you saying it isn't worth fixing? I was hoping you would and report back on what it took. Although I probably will never see one, at least I hope not!
Is it worth me fixing? No. Is it worth a buyer fixing? Maybe. It's gonna take a governor...or at least a circuit board, and I called around and was told it's probably obsolete. A re-man mechanical governor (which may or may not work right with the bucket equipment) is about $800. So at a minimum a buyer can figure purchase price plus $800 to get it running. Purchase price is hard to determine when it's not running...it's only worth what someone is willing to pay for it. I'll research similar trucks and calculate scrap value and come up with something. If you need the trees in your yard trimmed it would pay for itself in one use for what it costs to have big trees trimmed these days. ...granted everything still worked on it.
Why don't you call the bucket manufacturer and ask them if its their modification? I'm still leaning in that direction. There was no need for any electronic controls on a regular road truck. By the way, do you have any Emergency shutdown buttons that need to be reset? Saw that on a late model Ford with an E-stop in the bucket.
Good question. I didn't see an E-stop...checked bucket controls, ground controls, and cab. At any rate, there's only two wires going into the governor: key on 12v and a ground. I'm getting voltage and ground, so I don't think anything is interfering between the key switch and the governor. I may call the bucket manufacturer as you suggest. I've also got a number to a Detroit engine re-manufacturer that sells 8.2s. If the internals were the only difference, I'd suspect the bucket manufacture's modification. But the aluminum housing is different than the mechanical govs and it has a Detroit logo cast in it. If I find out anything, I'll post it...in case it helps someone in the future.
I called an authorized Detroit service dealer and spoke to the parts manager. The electronic governor was developed for vocational trucks. It's a Detroit item and is obsolete. They are programmed to hold certain RPM or to govern speed. He indicated that the programming may not be one size fits all which leads me to believe the programming is adjustable...probably by hooking a tool into the diagnostic port on the left side of the governor? Anyway, he said he has a used one that he believes came off a running engine but said he can't guarantee it's programed the same as mine or would even work...and he wants a few hundred bucks for it. Fair price IF it works, but it's a gamble. I'll have to think on it.
Hello did you ever get the issue resolved? I’m having the same issue with mine it looks the same as yours
Problem solved for mine bought a reman governor and swapped the chip board now it’s up and running again