Fuel pedal does not return

[crunchylicenseplates]

Worst flood since Hurricane Sandy hit within 4feet of my front door. Flooding and high water here is unavoidable. If you actually have some helpful info on dealing with high waters and trucks please dispel your expertise. EBR Sheriffs Office has 2 or 3 M35A2 trucks, I know because they were rolling around my neighborhood last August. Look up videos on YT on the topic Great Flood of 2016 to see my neighborhood underwater.


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[Speedwoble]

If you actually have some helpful info on dealing with high waters and trucks please dispel your expertise.

Pull the drain plugs to check for water in your gearboxes and check your clutch drain plug is removed.

 

[crunchylicenseplates]

Thanks for the advice. Ordered more MT-90 from Redline as draining gearbox and portal hubs requires refilling, and at $60 for a jug they better not be leaking, I'll be doing that very soon.
I will do more reading up on fording. I'm waiting for one of the few remaining snorkel kits from Unipaser and working on redoing my electrical system, got a new wiring harness from the UK as mine was modified from it's original and I need to put it back to a more robust and less fallible.

By the way a lot of folks here owns flat bottom boats, when put together they're called the Cajun Navy.

 

[tennmogger]

Hey Crunchy, can you tell me more about the replacement wiring harness you found? I have a 404 that needs complete wiring system.

Thanks

Bob

 

[crunchylicenseplates]

Here is how I found it, I did a search on our favorite auction site but changed the domain to .de and looked for vendors that ship Worldwide (weltweit) and your login for the .com site works for the german site.
Just do a search for: KABELBAUM KABELSATZ 4045400305/604041077800 UNIMOG 404 S in Google or on (that auction site to remain nameless with a .de as the domain).

I just did a search and found several postings for it.
I got mine from Westerfield 4x4 in the UK but he's all out.
Expect to pay about $100 for it with shipping to the US, and the wait time for shipping is usually pretty quick if it comes from EU.

For anyone else reading this, changing the domain to .co.uk, .de, .fr, etc will get you many more options in finding parts for your Unimog, just make sure they ship worldwide, ironically not all posts on these sites show up on the US site.

Moderators please don't flag this post, it's helpful information for helping Mog owners find parts.

 

[crunchylicenseplates]

This issue will not leave me alone.

Today while I was testing my Civilian Conversion Kit install, with drivers half of the doghouse off, I can step on the pedal or pull the throttle cable and the engine will rev up to about what I believe to be fast idle 1500 RPM or so and does not return back to idle of 850 to 950. The work I did before has the throttle cable is working very well however that does not appear to be the culprit anymore as the Crossover Shaft (DB#404 300 00 20) that sits inside the Bell Housing (DB#404 300 02 50) does not return fully. And the return that it's not travelling is minuscule.

When I push on what appears to be 1/64 of an inch (or a push that doesn't seem to travel at all) drops the RPM from 1500 to about 900 (normal idle). Each time I've had this issue over the past few months I've pumped the edges of that shaft going into the bell housing with Lithium Grease, yet I think it's either the return spring has been stretched that tiny amount over time, the shaft is rusted up / gummed up and/or the carb is dirty and needs to be cleaned. I'm leaning towards the Carb. Not that I don't relish the idea of pulling the fuel pedal linkage assembly out and cleaning it thoroughly.

One of my next tasks was to take the Carb off and clean it and rebuild it if necessary. Which leads to the next question, rebuild or swap out with a rebuild? I watched a video on a 32NDIX disassembly and the guy said that tuning the carb should be done by someone who has done it before. Any suggestions here? Rebuild kit is $139, replacement is $650 including core charge.

So for now driving with the drivers side of the doghouse off is my only option.
Which makes driving on hot, humid and wet days even more fun.

 

[tennmogger]

Check for end-play in the throttle shaft through the carb body, the shaft the butterfly plate is on. A little end play allows the oblong plate to hit the bore of the carb early, not closing all the way, so idle stays high. Usually just a little touch will center the plate and it closes. A little lube on the shaft might help.

 

[The FLU farm]

When I push on what appears to be 1/64 of an inch (or a push that doesn't seem to travel at all) drops the RPM from 1500 to about 900 (normal idle). Each time I've had this issue over the past few months I've pumped the edges of that shaft going into the bell housing with Lithium Grease, yet I think it's either the return spring has been stretched that tiny amount over time, the shaft is rusted up / gummed up and/or the carb is dirty and needs to be cleaned. I'm leaning towards the Carb. Not that I don't relish the idea of pulling the fuel pedal linkage assembly out and cleaning it thoroughly.

If you don't have a spring laying around to try with, I'd go to the store, splurge and spend a buck (possibly two) and buy a new one to find out if it's the spring.
Or, shorten one end of your existing spring. Not knowing what it looks like, I'm only guessing that it can be done, but usually it's easy enough.

 

[crunchylicenseplates]

Finally fixed the issue of my fuel pedal not returning. The problem in the end was the fuel pedal itself had no spring action left in it's own operation. It was pretty gummed up, all the throttle linkage was mucked up too. Parts to replace were not expensive from Unipaser and EI except the Fuel Pedal itself ($93!) and Michael from Unipaser told me I needed spring behind the fuel pedal. The Shop manual for the 404s does not include a diagram with this spring. I found it in the Teil 5 TDV2320 (page 102) Military Parts Guide though. Here's a screenshot.



Apparently some models did have this spring and some did not. Page 107 in the Teil 5 guide for the Fuel Pedal show my original configuration, while page 102 shows it with the spring. Maybe it was for the 404.0 or another model. All I know is that spring is making all the difference for this 404.114s

The fuel pedal comes with the elbow and nipple for throttle linkage already attached (don't let that picture above fool you, that elbow does not come off). The pedal has to be swung towards the engine to get the angled elbow out of the little hole in the chassis. Don't do what I did and hack out the old one with a saw and nick my oil gauge line (that part is no longer available).

The lower right footwell panel (that sit's under the doghouse) has to come out. The drivers seat and right support rail has to be removed first, then the panel. I don't think on my 404s this driver side footwell panel had ever been removed, no amount of Acetone / AFT mix would loosen these screws. Some had to be drilled out and the holes re-threaded. Once that was done, the new pedal went in without an issue.

If you're ever unlucky enough to replace the fuel pedal, you'll need one person in the cab with a wrench and another underneath with another wrench to work the bolts.

The other item to watch out for is the return spring that came on the truck is bigger than the replacements you will get currently. The newer spring looks smaller, but it works just fine. The cross over shaft has 2 plastic inserts on in each of the steel tubes, don't lose these. I used a 22LR cleaner swabs to clean the tubes out of muck.

I fired her up and after she warmed up, the fuel pedal and throttle linkage are all working as they are supposed to. Hopefully I can put this one to bed for a while.

 

[The FLU farm]

Hopefully I can put this one to bed for a while.

\

I hope so, too. But if it happens again, is there any reason why you couldn't add a spring to the system elsewhere, or replace an existing one with a stronger version?

 

[crunchylicenseplates]

\

I hope so, too. But if it happens again, is there any reason why you couldn't add a spring to the system elsewhere, or replace an existing one with a stronger version?

I researched that, and the only springs are the return spring and this pedal spring. In this situation, the return spring was not enough to return the engine to normal idle, it needed another nudge which this pedal spring provides. In the event the fuel pedal ever gums up the added spring will give it the nudge it needs.

As long as the floor panel screws are not an issue to remove then replacing the pedal and/or putting in this spring is a breeze.

 

[FarmMOG]

Thanks for the advice. Ordered more MT-90 from Redline as draining gearbox and portal hubs requires refilling, and at $60 for a jug they better not be leaking, I'll be doing that very soon.

I just replaced the transmission, differential, and hub oil in my SEE. I read a lot of posts, asked some questions, and after reading a very informative but long paper on the differences of GL4 and GL5 fluids, made sure to not put the wrong fluids in the wrong place. There is a long discussion about this on the owners blog, buried but somewhere near the end of the almost 400 pages. GL4 fluid is only for the transmission with brass synchros and GL5 is for the differentials and hubs. Using the wrong fluid in the wrong place could increase wear and decrease life expectancy of components. Take a look on the other blog and see what you come up with.
On another note, I am not sure if your vehicle has the air controlled differential locks, but there has been several discussions about oiling these every year. I still have to do this on mine, but after reading about you driving through flood water, might be worthwhile to do it. There is a lot of great info on the owners page, but reading it all takes a very long time.

Good luck,
FarmMOG