Got a M1009 with a 6.5 NA

[PaFarmer]

Bought a 1984 M1009. My first CUCV. It has a 6.5 rather than a 6.2. Did the govt retrofit 6.5 NA motors in some CUCVs or was this a modification during its time in civilian ownership. It was for sale cheap, so I hauled it home. I seem to be losing prime. I read some threads and replaced the fuel filter and looked for leaks. I cannot find any leaks. I'll keep plugging away at it.

 

[CUCVLOVER]

Hello.
Welcome the cucv land.

So to start I have a couple questions for you.

1: does the truck have the factory square box style filter?

2. Is that tag that says 6.5 on the air cleaner?
3. if you get on top of the engine and look down at the front of the block around the water pump you should be able to see it cast into the block what it is.
On my 6.2 it says (6.2 na diesel) on the passenger side near the water pump, but you can only see from on top.

How about some under hood pics?

It's is a nice truck.

Thanks

 

[Chief_919]

The military switched to 6.5's for everything once the supply of 6.2's ran out, so if it was in service longer than the typicla one was it could have had a 6.5 installed.

But, as CUCVLOVER said what marking are on the block? You also see valve covers and heads swapped so the sticker doesn't prove its really a 6.5.

 

[PaFarmer]

The pic I posted was on the valve cover on the driver side. It has a square fuel filter on the passenger firewall. I'll check the top of the motor to see what is cast on the block. It makes sense that they might have swapped parts. Really I am just curious. It was from NC so that likely explains the minimal rust vs the trucks I typically see from the northeast. I hope to keep it stock, though if the motor gives me problems, it might get a 5.3 gas motor.

 

[CUCVLOVER]

I think we need a few pictures to tell more.

As far as the fuel issue I would suspect that the filter assembly is gone bad
When you pulled the filter I'm sure you saw that large round thing? That thing can leak air into the system and cause many issues. Go to Napa or whatever you like best and get a small clear inline filter that will except 3/8s and 1/4 fuel line. You prime the system then put that filter in inplace of the box unit and see if your fuel issues go away.
The filter I used to that was only like 2 bucks.
If they do report back here.
Hope this helps

 

[PaFarmer]

I could not find a code cast in the block. Here are some pics of the top of the motor and valve cover. I plan to replace the rubber fuel lines. It looks to have several sizes of rubber hose. Any guidance on the sizes I need to get?

 

[Warthog]

If the valve covers are correct you have a General Engine Products (GEP) engine from AM General. They are a better design that the GM versions.

http://www.amgeneral.com/vehicles/gep/

They took over production around 2000 and supply the military with replacement engines.

Some places to check for air leaks:

fuel heater on the filter block under the filter
all the rubber lines

 

[Al Harvey]

To start with, for your fuel losing prime, the two lines coming off the filter housing. They will be on the driver's side of the housing towards the top. I do believe the short one is 3/8 and the long one is 5/16, but don't quote me on that. Look at the larger diameter hose from the filter housing, it runs towards the intake and connects to a metal line right there. The smaller diameter hose will run right next to the same spot on the intake as the larger one, but then it continues under the intake and to the center line on the injector pump. To see this you will have to look under your intake. Everything your probably gonna think is telling you to pull the intake, but you don't have to. Use a long screw driver to reach in from the driver side and you can eventually get the clamp loose. To pull it off and to install the new one, reach over the intake from behind and you can reach most of the was up there. Now I do say this being 6'4" lol. The next line to replace will be at the front of the passenger frame. If you look down at the front of the motor from the passenger fender you should be able to see the fuel pump. There is one short rubber line on the pump. I again believe it's a 3/8 line. Make sure your new line is a little longer then your factory one since it's a preformed line and you don't want to kink the new line. Start with those lines, the next rubber lines you'll probably need to replace will be the vacuum lines.

Also while your looking under the intake manifold, see if there is a build up of any fluid sitting under there, if so that might give us another idea to where the prime is going. But start with the rubber first. Good Luck.