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Author Topic: Stuck injector  (Read 2702 times)
Len Silva
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« on: November 09, 2006, 12:29:59 PM »

I tried to start my 4104 for the first time in about five years and got nothing, not even a little smoke.  I used an electric pump and ran temporary fuel lines into a can and ran the pump until I got good air bubble free flow at the return - still nothing.

To make a long story short, I pulled the valve cover and found the injector rack is stuck hard in the no fuel position. Neither the stop solenoid or the governor is holding it so I assume one or more stuck injectors.  This is not something I've ever messed with so I'm looking for advice on how best to find and free the injector(s).

If I carefully pull one injector at a time, can I safely put it back without having to worry about adjustng it?

Any help most appreciated.

Len
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« Reply #1 on: November 09, 2006, 01:25:00 PM »

Start by pulling the pin that connects the governor to the rack to find out if it is the rack or the governor that is stuck. HTH
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Len Silva
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« Reply #2 on: November 09, 2006, 01:28:47 PM »

Start by pulling the pin that connects the governor to the rack to find out if it is the rack or the governor that is stuck. HTH

I've done that, both the governor and stop solenoid.

Len
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« Reply #3 on: November 09, 2006, 02:57:06 PM »

Len If you pull injector you will have to adjust them when you put it back. I would try a little very little starting fluid and see if you can get it to fire off

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« Reply #4 on: November 09, 2006, 03:11:21 PM »

Len, before you start fooling around with this engine you should try and get the counsel of an old DD mechanic.  If, as you believe, the rack is stuck in the "No Fuel" position there's no way you're going to get that engine to start.

Sometimes a little 'tap' with a very small hammer (don't get carried away...injectors are very precise) might do the job.  You didn't mention is it was the 6-71 or the 8V71...but taking the pin out of the 'rack' between the governor and the pipe that controls the injectors might give you an idea where it's bound up and always put the cotter pin back in place.   NOTE:  DO NOT start the engine with that pin out!  The engine could go into overspeed and you don't want to be around in that event!

Leaving one of these little beasties sitting this long is almost near fatal...not for the engine but for the fuel system.

DO get a DD mechanic to look at it...and save yourself a lot of grief.

NCbob
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Len Silva
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« Reply #5 on: November 09, 2006, 03:24:25 PM »

It's an inline 6-71.  Should the rack move freely with the engine stopped, or should there be downward pressure on the injector when you attempt to move the rack?

I doubt I'm going to find an old DD mechanic within a hundred miles.  (I'm between Gainesville and Lake City, Florida if anybody knows someone.)

I have the engine manual and I've wrenched on gassers many years ago but this is the first time I've even had the valve cover off this engine.

Can I remove the control tube and attempt to operate each injector manually to find the stuck one(s)? Can I remove and replace the control tube without having to do any adjustments?

Thanks,

Len
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« Reply #6 on: November 09, 2006, 03:33:21 PM »

Hello Len.

There is a serious safety issue here for you.

Your second huge concern after the injectors being stuck closed is what happens if they stick open once you get it to start!

If that motor starts to run away, it will break, and parts will easily explode out of it, causing serious harm to whoever is standing nearby.

I think you will be wanting to check the proper functioning of all of it. You have a real chance of having more than one problem in there.

Da' book will guide you!

happy coaching!
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« Reply #7 on: November 09, 2006, 03:44:48 PM »

OK, it's a 6-71.  You have a shaft ( about 1/4" diameter) coming from the Governor to the end of the "Rack", the black pipe with all those adjustable gizzies with fingers going to each injector.  At the end of the black pipe there is a clevis pin with a cotter pin on each side.  Remove one of the cotter pins  and see if the "rack" will move freely.  That will tell you if you have a stuck 'rack', possibly a stuck injector or if all is free..a Governor problem.  DO NOT start the engine with that clevis pin out!

It's also not a good idea to change any of the screw adjustments on the 'rack'.  Were it me, I'd remove all 8 of the 1/4-20 hex head cap screws and remove the whole rack and check the "in-out" on each individual injector.  The reason I suggest that is because when you re-install the rack...you should be pretty close to the last rack adjustment and the engine should run (if all the individual injector racks are free).

They should travel from front to back with little effort.

Again, if there's a doubt...call Dallas!  He hasn't screwed anything up in months! Wink
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« Reply #8 on: November 09, 2006, 04:08:37 PM »

OK, I went back and looked again.  Without taking anything apart, just moving each injector rack the tiny amount of play in the actuator, they all moved except no. 2.  It was rock solid and the injector is stuck in the down position.  All the others seem to operate OK.

I guess I'll pull the injector and see what I can do to free it up.  I've never done it and don't have any type of jig as shown in the book, but I'll see what it looks like.  Open to any ideas.

Len
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« Reply #9 on: November 09, 2006, 06:29:31 PM »

Len

if it's been sitting that long you will probably have to replace all the injectors. but to get it running try tapping on the number two stuck injector lightly as turning over if all else was ok you might have to use a shot of ether to keep from burning up a starter if you was getting any fuel you should of had blue smoke  at the least. I think you may have a fuel pump problem also.

Get a garden sprayer and fill with fuel and remove fuel line from tank and put a fitting on sprayer that will fit into primary filter and pump it up and then turn it over and see if it starts it should start on 5 cyl and miss on the one stuck and with the fuel in the lines stuck inj may free up enough to run.

LarryH
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« Reply #10 on: November 09, 2006, 07:10:30 PM »

Len wouldn't have any fuel delivery with the rack held closed by a stuck injector? So maybe no smoke?
My best guess would be deal with the stuck injector first...and only after that problem is resolved, and still no fuel delivery would the fuel pump be suspect. DD gear driven pumps don't cause much trouble. Even sitting is unlikely to kill it...may lose a seal and leak, but it'd still make fuel pressure....? While working on the injector, a fuel pressure guage could be temporarily attached into the fuel pump line...after the pump. That'll resolve the fuel pump issue.
Would any damage befall the gov or rack linkage by cranking with ether with the rack held closed? It'll very likely fire up on ether.
May want to pull that injector and check for water contamination.
Len, your biggest potential for problems will be related to the jumpers that feed the injectors. They must be carefully tightened or they'll loosen and leak, or if overtightened they'll may crack and leak. Leaking jumpers will fill the engine with fuel...
Most truck supply houses...NAPA, Snap-On, etc have both the little torque wrench (socket) for the jumpers, and the guages for setting the injectors. Check the book and make sure that you get the correct guages.
A DD will run with the injectors considerably out of adjustment. And as Bob says, you won't change it much (still need setup when finished) as long as you don't alter screw adjustments.
Be certain that when you finish, the rack moves to the "no fuel" position freely.
If I were doing this, I'd have a contingency....garbage can lid, or whatever to stuff in the intake should it become necessary. Do 6/71s have emergency shutdown butterfly? If not, remove some part of the intake so that you can get a good seal with something flat and solid...not rags or towels. Don't let it run away... Shocked
Could always pick up another injector and throw it in....if it runs well...good enough. Probably, the injectors should be rebuilt after sitting that long. Do you plan to use the bus? Or just get it running? No need in spending money on a set of injectors if you plan to continue storing the bus.
Good luck dude!
My dos centavos, JR





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« Reply #11 on: November 09, 2006, 08:18:03 PM »

I have an electric fuel pump back at the tank for priming and that's what I'm using now. Getting good fuel flow through the head and no bubbles in the return.

I did use a little ether and got it to spin just a little faster but that's all. Just a couple of quick shots - got enough problems already.

Someone on the other board talking about unused engines said he has used an electric fuel pump to circulate laquer thinner through the head for about thirty minutes and that that freed up all his injectors. He then flushed the head with clean fuel before attempting to start. Maybe I'll try that first, laquer thiner or carb cleaner. What do you guys think?

As far as the bus, I haven't decided yet whether I'm doing this to use it or just to sell it. I went and bought a nice motor home but after only a couple of months, I'd rather be driving the old beat up bus.

BTW the Vogue MH is for sale!

Thanks for all the help,

Len
« Last Edit: November 09, 2006, 08:27:03 PM by Len Silva » Logged


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« Reply #12 on: November 09, 2006, 08:50:23 PM »

The 6-71 has an electric emergency shutoff which can be operated by hand. Make sure you know where this is before you try to start it. It is in plain view at the left center-a small cam with its edge facing to the rear with a small pin attached to an electric solenoid at the top of the cam. The cam can be operated by hand by lifting the pin slightly. The pin should be sitting in the flat of the offset notch in the cam when the intake is open. When the pin is raised out of the notch the valve closes by a spring.

This valve is a neat theft prevention device also.

Is it possible this valve is shut? Could be your problem. It will never start with this valve closed no matter how well the fuel delivery works because it closes off the air intake to the blower box.

You really should have at least one manual before you mess with this engine, not only for safety but to save hours and hours of working by guess. Both the maintenance and operating manuals. clearly explain the emergency shutoff operation.
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« Reply #13 on: November 10, 2006, 04:21:04 AM »

Len,I had the same problem when I bought my bus when I first looked at it we started it and it ran great but had been sitting for five years,a week later when I went to pick it up no start,I checked everything out and found I had a stuck injector,picked up a new injector and installed it and made sure that the rocker to the injector had some clerance and it started and ran fine for 120 miles home and then I ran the rack at home where I had the tools and time to do it,it only took a little over an hour to change the injector and I am sure you could do this and then be able to drive it to someone to adjust your rack   Mike
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« Reply #14 on: November 10, 2006, 05:15:11 AM »

Len

After you posted more info on what you have tryed I would say that your emergency shutoff is tripped and you are getting no air into blower so check the complete system and make sure all are in correect position no start or smoke usually means no air.

LarryH
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« Reply #15 on: November 10, 2006, 06:51:41 AM »

I do have the manuals and the shut down is not tripped. I have rigged a temporary setup so that I can trip it from the rear with a 6' cord in case of a run away.

I am reasonably "book smart" on this bus, read all the manuals cover to cover, just no hands on with the injector system.  I am trying to learn all I can from a practical point so as not to make any stupid (expensive) mistakes.

Thanks all,

Len
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Len Silva
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« Reply #16 on: November 13, 2006, 01:55:10 PM »

I ran lacquer thinner  through the head with an electric fuel pump for about an hour (a hint I read about somewhere), no joy.  No. 2 injector still stuck tight as a drum.

I tried to pull the injector but because the injector rack is stuck all the way out, I can't get it past the control tube.  I'll have to remove the tube to continue.

The other five injectors work but they a very stiff, don't return to idle without manual help.

So, where do I get injectors and what should I expect to pay for them? I've seen them from $158.00 each to $15.00 on eBay.  I don't know what I have until I get it out.

Anybody know a DD guy in North Central Florida/South Georgia?

Thanks,

Len
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« Reply #17 on: November 14, 2006, 09:15:08 AM »

I was pretty depressed yesterday, five very stiff injectors and one completely locked up.  I went out this morning and what do you think?  The rack worked smoothly and the one stuck injector that I had removed was free.

Put it all back together and using an electric fuel pump straight in and out of the head, it started on the first turn.  A little lopey at idle but strong and smooth with just a little fuel.

I only ran it for a minute and now I'll go put the whole fuel system back together.

It's a good day  Cheesy

Len
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« Reply #18 on: November 14, 2006, 09:21:52 AM »

Good for you Len,glad to hear things are working in your favor now  Mike
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