Up & Down Idle Speed

[DKasper]

Hi Guys,

I'm starting to feel like I broke something -- the other day I was towing a few horses through some hilly country, so I shut off O/D and just went along at about 45 - 55 mph. The engine's turning at a max of about 2600 RPM in that range.



After I arrived and was letting things cool down, i noticed that the engine had developed a "stumble" -- RPM's would drop by about 150 for just a second then it would go back to normal, drop, back up, drop. . . you get the picture.



After the return trip I noticed it was getting a bit worse, and now it's more of a continuous up & down cycling -- kind of like if the grid heaters were doing and consistent on/off/on cycle, but not as smooth. The voltmeter isn't budging, so I know it's not that.



I changed the fuel filter - old one was only in for 5k, but you never know. No change in the symptoms.



I don't notice anything at speed, but if I press the accelorator enough to raise RPM's up to 1200, I still can hear a speed variation. By the time you get to 1600 RPM or so you can't hear that anything's wrong.



At this point, I'm kind of scared to drive it. I'm starting to think maybe a governor spring problem? I'm a step away from taking it in to a local shop, but would much rather check things out myself if possible -- I just don't know what to check!



Many thanks,



Dave

 

[Greenleaf]

Turn off the A/C



OK then... ... ... ... ... it's time to open her up.

Remove the shut-off solenoid and observe the magnet for metal shavings.



Then, open up the top. Take a good look-see in there.



-S

 

[bgilbert]

Yeah did you have your AC on while stopped and this happened? Bill

 

[DKasper]

Thanks for the feedback, guys -- AC was off the whole time. It's a much more sudden fluctuation and not as smooth as a load being put on the engine.



Scott, I'll try your ide of pulling the shutoff solenoid tonight -- do you know if there are any special tools to get that off? I'm guessing it's metric and I don't have any monster metric wrenches.



I've never gone in the pump before -- when you say "open the top", do you mean under the TPS? I was looking at the VE thread at the top of the forum trying to get an idea of how that would work -- any further explanation would be great!



Thanks

Dave

 

[Greenleaf]

There are a no. of things;



How far is your full load screw turned in?

Sucking any air? (check lines)

Throttle linkages binding?

Lift pump PSI?

How old are the injectors?

Has it done this before when the engine is good and hot?



The top of the pump separates just under the AFC housing.



Don't recall the size of the wrench used to R&R the solenoid. You may need to employ use of a cut- off wheel to remove the top portion of the pump's rear support bracket.



-S

 

[JLEONARD]

Dave,

Send an e-mail to me at

-- email address removed --

and I'll reply with a .pdf copy of the VE pump manual. It may help you out.

Jay

 

[dpuckett]

Solenoid is a 24mm or 10" vice grips angled in there.



It soudns like a fuel delilvery problem. First check to see the blue wire is going to the solenoid and is hooked up firmly.



Next check for fuel leaks. I wouldnt think you would suck air without having some fuel leakage- the entire system is under at least a little pressure. I could be wrong, though.



Then lift pump PSI- goes back to delivery.



Injectors. If one is really bad, it can cause a stumble and rough running. most places will pop check them for free if you pull them.



If it is the pump, you can get a 240hp pump and hammer down. Oo.



Daniel

 

[BushWakr - RIP]

Do the other stuff suggested... . if you have no luck I don't think I wanna say what I'm thinking... .



pb

 

[DKasper]

Update -- I couldn't pull the solenoid last night -- didn't have a metric wrench big enough and I've buggered things up before with Vise-grips, so thanks to Daniel, I'll be getting a 24mm wrench at lunch today and take it off tonight.



I did check voltage to the solenoid wire and that looked good.



The leak check went fine -- didn't see any, so I washed down the engine and checked again. Still no signs of fuel.



I pulled 2 injectors just to get a general idea of condition and they looked fine, even though they are original. I suppose there may be a bad apple in one of the other cylinders.



I was talking to a friend who works on a lot of tractors, and he was saying maybe one of the return springs in the pump blew up -- not sure if that would show itself with the solenoid removal or not, but it sure didn't sound good!



So, I'll pull the solenoid tonight and see what's waiting inside.

A huge "Thanks" to everyone for your help! I'll keep you posted . . .



Dave

 

[BushWakr - RIP]

Well..... ???? were you at bud... ???



pb...

 

[DKasper]

Well Guys, it doesn't look good.

After hacksawing off the top of the rear pump mount so I could get to the solenoid, I swept around inside with a pencil magnet and came up with about 8 bits of pretty flat metal -- not very large, but I'm guessing that I shouldn't have found anything!



I found a guy who works at the best injection/pump shop in town who's willing to take a look at it as an after-hours job -- he says it will be about half what it would cost me if I walked through the door during business hours. They've done some injector work for me before on a Deutz engine I've got in an older pickup.



So, I'll be looking up the old threads here on pulling pumps, and between the shop manual and those, I should be able to get it figured out. Wish I had the time & dollars to send it off to the Great White North -- that would be PDR -- to give it some special treatment!



I still want to check the lift pump pressure and make sure it's getting enough fuel and that a starvation condition didn't cause this one to bite the dust. I think I have a pressure gauge located that I can borrow -- Pastor Bob, any tips on how to plumb that setup?



Thanks again to Jay for the pump manual -- it's really great!!



Thanks to all for your ideas & wisdom -- I'll keep you posted on the pump removal.



Cheers,



Dave

 

[Greenleaf]

If I recall.....



Without looking, there is a steel line... ... ... ... hold that thought... i need to look



Okee Dokee then. The steel line from top of filter housing to top of injection pump. Look to wards the top of the filter housing you will notice a banjo fitting w/a very small bleeder screw. Throw that banjo bolt away..... ask me nice like and I'll send you a NEW banjo bolt with 1/8th inch pipe thread in place of the stupid little bleeder thingy. This is how I have a gauge in my fuel system



-S

 

[DKasper]

PrettyPretty PrettyPlease?????

Thank you Scott -- look for a PM in a few. . .



Dave

 

[BushWakr - RIP]

Oh lordy... I can hear the snivelling from way up here... .



When your buddy does the pump, have him pin it at 1. 7 mm plunger lift. That will be your initial starting point for your timing once you re-install the pump. When you put it back on, make sure the stock tic-marks/index marks on the pump housing and gear cover are lined up dead on. At that point you'll be starting with some good advance already built in.



You should also PM me for a couple other items too...



pb.

 

[Stomp]

Pastor Bob

Now Pastor I thought I was the only one getting the secrets?:-laf :-laf

 

[MMiller]

When I first saw this thread, I thought about those springs too. Mine broke long before I knew about this webcite.



My truck however would take off going down the road, push black smoke out the exhuast and give you a ride before turning to normal. This was when the truck was stock.



It idled funny once in a while too.



Michael

 

[DKasper]

Hi Everybody,

Well, it took a few days, but finally had time to get the pump off last night. Talk about contortions -- I suppose it will get easier after I've done it a few times, but then hopefully I won't be having problems that require pump removal very often!



My friend is going to go through it this weekend and see what's up. He's guessing return spring, but we'll see . . .



I did replace the lift pump just for peace of mind.



I'll keep you posted on what we find!



Dave