Dodge fuel problem

[Keith-wc42]

Went out in a convoy on Sunday in the WC42.

Had the common fuel starvation problem.

On my way to the randevou point, probably 10 minutes of driving i had a couple of misfires while going around a roundabout, then a little further on the engine quit. It started again no problems.

Around 15 minutes into driving in the convoy, it misfired a few time before cutting out again, this time it wouldn't start. We ended up doing all sorrts of tests and found the ignition system was good. It seemed to me that after trying many things to get it going, then only thing that actually did make it go was the passing of time since it quit.

It run again for a while, but was misfiring and backfiring before it happened again. this time we managed to break the screw on the fuel pump bail (where the screw clips onto the wire frame), so we towed it to a safe location and left it there while i went as a passenger in a command car.

We went back to the Dodge at the end of the day with another screw for the fuel pump bail (Im still looking for a new one as this spare screw is very scruffy). I drove quite a long way home without problems. It was around 7:30pm so even though it was still warm outside, it was much cooler than it was during the day.

Im thinking of changing the fuel lines, starting from the tank to the filter first, cleaning the filter and changing the filter element and then see how things go.

I would like to take the tank off, but its pretty full and im thinking about avoiding this for now.

 

We ended up having the same problem with the command car in the convoy and two jeeps. It was a very hot day.

Any tips on what i should try? I was thinking of making a new copper fuel line from the pump to the carb....making it longer so i can run it further away from any heat sources.

Edited July 20, 2021 by Keith-wc42

[Richard Farrant]

Keith, don't use copper for the fuel pipes as they absorb heat, used steel pipes and if any pipes are in the vicinity of the exhaust manifold used an insulating lagging material. Years ago I did this on my Bedford with asbestos string obtained from a hardware shop in deepest Normandy, it did the trick.

[Keith-wc42]

Thanks for your reply Richard.

The fuel lines are already copper. The line from the pump to the carb runs closer to the manifold than I would like.

I may try either changing this line or at least insulating it first then before doing anything else.

My Dad was a hose fitter for many years and still was when he passed away, so there is a good chance the hoses are fine.

[johnwardle]

It could be a good idea to pressure test the fuel line, a friend of mine had exactly the same symptoms on his Dodge, after overhauling the fuel pump to no avail he fitted an electric fuel pump. When he turned the ignition on a very fine jet of petrol shot out of the fuel pipe, the hole was so small it was virtually impossible to see. After replacing the fuel pipe and removing the electric pump it still runs fine.

[Gordon_M]

Insulate the fuel line, make sure you have the heat shield in place above the pump.  

I have idly wondered if reproducing the heat shield in stainless may not make it work a bit better than the original mild steel.

[Keith-wc42]

It has the heat shield Gordon.

While it may look ugly, there is plenty of room to run a longer line which avoids the manifold more. Obviously though, it's still going to run above the head where it goes into the carb.

I will try insulating it first and maybe changing that line from the pump to the carb.

It always starts right on the button and runs fine at first and it seems to me that the thing that gets it running again after it dies is the passing of time....cooling down maybe.

 

How they got by in the desert though in WWII makes me wonder.

[Keith-wc42]

20 minutes ago, johnwardle said:

It could be a good idea to pressure test the fuel line, a friend of mine had exactly the same symptoms on his Dodge, after overhauling the fuel pump to no avail he fitted an electric fuel pump. When he turned the ignition on a very fine jet of petrol shot out of the fuel pipe, the hole was so small it was virtually impossible to see. After replacing the fuel pipe and removing the electric pump it still runs fine.

I will check for that John, thanks for your reply.

[Pete Ashby]

On 7/20/2021 at 9:05 PM, Keith-wc42 said:

It always starts right on the button and runs fine at first and it seems to me that the thing that gets it running again after it dies is the passing of time....cooling down maybe.

 

How they got by in the desert though in WWII makes me wonder.

Your right with regard to the restart providing it is vaporization you are suffering from then when everything cools down the problem goes away. 

Fuel pumps  will not pump vapour either in the feed line or the pump chamber so that's problem 1. 

Problem 2 occurs with heat soak from the exhaust system via the inlet manifold and then into the carburetor this problem usually occurs after the engine has been shut down then restart attempted within a short time period.  Fuel in the float bowl will expand and possibly boil.  The net result here is this pushes raw fuel through the various power circuits then  dribble into the inlet manifold where it forms varpour  which the ignition system cannot ignite due to the wrong oxygen to fuel ratio ( 14.7 to 1  as a rule of thumb).     This is why after a lot of cranking with the throttle held fully open providing your battery is up to it, the  engine will if your lucky,  couch into sluggish reluctant life accompanied by clouds of black smoke made up of virtually raw fuel issuing out of the tail pipe.  Couple this with the vaporization in the fuel pump and or feed lines and it's not looking good for that rapid get away from the pub car park in front of the gathered admiring crowd of onlookers.

Your last point about how did these trucks operate in desert conditions is an interesting one and one that I have asked myself too. 

It falls under the same set of discussions to my mind that center around the 6 volt  vs 12 volt discussions that rumble around on any WW2 truck forum,  camp fire or beer tent  you choose to visit. 

My take on this is if it didn't work then in nearly six years of war time operation carried out by the two largest automotive nations in the world it would have been changed pretty dam quickly.  This can be seen in a number of different spheres of military automotive design during the war.

All very interesting but it hasn't addressed your question. For what it's worth my thoughts on your direct question are as follows:

1 Equipment was all factory new and by this I mean everything that goes to make up the vehicle.

2 Petrol was of a different octane rating without all the go faster cheaper additives that come as standard from the pump now .

3 There were a number of actions taken by troops in the field to alleviate some of the issues,  from the simple act of wrapping a rag around the fuel pump then  having a bod sit on the wing to keep dripping water on it (not really practical on a jaunt to Tesco's these days) to taking the engine covers off and throwing them away ( not very good for the resale value of your vehicle), this is before we get onto fabricating overflow tanks out of 2 gallon cans ect.

Pete

 

[Nick Johns]

A common problem of vehicles dying in warm weather, no one ever thinks to check the position of the exhaust manifold hot spot, it probably is set in the Winter position so in summer overheats the inlet manifold and causes vapour locks, they often can be difficult to reset as they seize up in the manifold

Edited July 23, 2021 by Nick Johns

[Keith-wc42]

Thanks for all your help and advice.

I will always make sure I carry plenty of water to try and cool things down.

Maybe we should all park our military vehicles up through the summer and only take them out when its snowing!

[Pete Ashby]

2 hours ago, Keith-wc42 said:

 

I will always make sure I carry plenty of water to try and cool things down.

 

Just a word to the wise, be wary of pouring cold water in any quantity over hot castings like your manifolds  for example.  The sudden thermal shock may well cause distortion or even cracking of the cast.  Much better to wet a rag and wrap it round the pump, or fuel lines, or carb then remember to remove it before trying to restart the engine as you don't want the rag getting picked up by fan.

Pete

[Keith-wc42]

Yes Pete, I should have said that I've been avoiding the head, block etc....I was using water last Sunday trying to get the command car going after my panel Van was abandoned. My t-shirt ended being used as a wet rag for the parts I couldn't pour water onto (my drinking water that was).

The water "seemed" to work, but again it could have just been the passing of some time. It was one of those repair jobs similar to just hitting something. It worked but there was no clear method to it.

Edited July 23, 2021 by Keith-wc42
Spelling after 5 whiskey's

[Keith-wc42]

Can anyone tell me the best type of fuel filter to get for this 1/2 ton Dodge and where i can get one from pretty quickly.

Not sure when the filter was last changed and where i would normally not ask the above, i want to have a new filter by next weekend if possible.

[Gordon_M]

You don’t change the filter, you drain it, or strip it and clean it. As a quick fix undo the drain plug and assess what comes out. If it isn’t clean put one of those little plastic lawnmower filters in line temporarily.  Do not dismantle the main filter unless you are confident you can get it back together and sealed - easy to break / strip. 

[7VHU]

Hi Keith, glass fibre exhaust tape may work in place of asbestos.

I’ve had issues with fuel vaporisation in slow moving traffic, not a great place to be!
Putting it down the the modern fuel mix being more volatile and running a little hotter, with an engine mounted mechanical pump.

I tried fitting an electric pump closet to the fuel tank and this seems to help when running but hot starting is still ****

Better than my old 80” Landie that used to suffer from carburettor icing!

How do the flathead V8s get on with the pump on the top of the engine….

Yep, winter rallies might be the solution if it wasn’t for the road salt.

Brgds

Peter

(Dennis light 4)

[Keith-wc42]

Thanks Gordon's, I thought it had a filter element in there.

Thanks Peter, I will look into that for the fuel line from the pump to the carb.

There are fuel line covers available to buy from places like demon tweaks. Not sure how good they are though.

[Gordon_M]

It does have a filter element in there Keith, thin stacked brass sheets, endlessly cleanable.   The problem is the gasket at the top the housing doesn't re-use well, and owners strip the bolt thread by over-tightening trying to get it to seal.  I generally suggest not to dismantle the housing unless you have a complete spare

[Keith-wc42]

Ok thanks Gordon. Considering that the filter is probably more than likely not the problem and just the extremely high temperature on that day was, I'll leave messing around with the filter.

Five out of the seven vehicles in the convoy that day broke down with the same problem.

[Gordon_M]

Worth draining it anyway, the drain is a simple hex plug.

[Keith-wc42]

Will do Gordon, thanks.

Im going to order some nickel fuel line and replace the copper line from the pump to the carb, so i can run it further away from the manifold.

What size is this fuel line? My vernier gauge has gone walkabout.

[Keith-wc42]

I made a new fuel line and also drained the fuel filter. There was a lot of "mud" in the fuel I drained out.

It run perfect yesterday, not a single miss fire. Even when we're were driving at walking speed for a while following a parade of ex paras it ran great and the temperature only went up to around 150.

I fitted new spark plugs though and after pulling them out again after only a few minutes of running they are black.

Plugs two and four were wet and black.

I just hope it's not the valve seals or piston rings. Since my Dad rebuilt the engine it's hardly done any miles though.

Next job will be to rebuild the carb.

[panzermechaniker]

Had a similar issue on our jeep, it would run great but after sometime it would sputter and quit and only after sitting a while would it start up again. We had fuel starvation issues.

We checked the carb and fuel line and filter but never could see any issue. What we found was that a small piece of rubber like debris had balled up and would get sucked into the pickup tube and would block fuel flow, and after time it would settle back to the bottom of the tank. By the time we would check everything the debris had already settled clearing the blockage, it took a while to finally catch it. Maintain a very clean fuel system

[7VHU]

My 7v once had a leaf (from a tree) in the tank. Used to float over the outlet.

I put a short tube of perforated sheet in it to stop the blockage.

[Jerry Jeep]

i had this with a dodge you could start it leave it running all day but when you took it out it would just stop running and it was rust in the tank that blocked the pick up pipe take a look inside through the float sender hole  

[Jessie The Jeep]

I had a problem caused by a failing coil. It would start cold fine and run fine, even for a long time. However, when hot, while it would run fine if kept going, it wouldn't start hot until it cooled down a while.