My M1009 has died new curve ball thrown Updated

[cucvmule]

Looks like I will drop the tank this weekend

Salty dog, since you have just recently owned the truck there is nothing wrong with dropping tank and confirm that supply is clean, water and dirt free. More problems are caused by contaminated fuel that progresses to clog filters, and ruin IP. On my civi 82 Silverado they put drain petcocks on both tanks to purge water from the tank at regular intervals. Why the military did not require is unknown.

I myself have dropped tanks on every car and truck I have ever owned because of buying fuel at stations that have contaminated tanks themselves. You never know when or where it can happen. Even new stations and tanks can get a load of bad fuel that goes out into the cars and trucks.

And also replace all rubber fuel line while you are at it. Even if it looks new do it anyway. The fuel line breaks down and particles of the hose will clog filter also. Most of the rubber hose is easy to get to, but the one behind the passenger fender well hardly ever gets replaced. And always check clamps for being tight. Small air leaks create all sorts of persistent problems.

Do it now and completely and you will hopefully have many trouble free years from fuel contamination. As Keith_J has said, "If you want a job done right" I do it myself.

And if there is any rust in the tank just replace it, they are not that expensive. I keep 2 extra here, one each side because of the fuel being sold at service station almost always have water in the systems. But I have 5 trucks that I drive, gas and diesels. Same tanks.

The straps almost always break but depending on how you do it you might not have to remove them. Drop by the saddles. Spray them up a day early might help.

 

[cucvmule]

I also run a 2 spin on filter system on my diesels. 1 primary 5 micron with water drain petcock and the secondary 1 micron that does the job well. If the system is new and clean the filters last a real long time. I may change the primary 3 times before the secondary gets replaced.

 

[87cr250r]

My 1986 truck has most of the original rubber. It's good stuff. Be careful buying aftermarket. You need to spec the hose properly, the stuff on the rack at the auto parts store is not the right stuff, especially for return lines as the fuel is hot. The trucks came from the factory with Viton lines for most of the return stuff and it's all still like new 40 years later.

 

[Keith_J]

Looks like I will drop the tank this weekend

Do you have a hand vacuum pump? Like Mity Vac? Try to draw diesel into the filter housing. You can also draw fuel through the IP.

 

[Salty dog]

Do you have a hand vacuum pump? Like Mity Vac? Try to draw diesel into the filter housing. You can also draw fuel through the IP.

What would be the procedure to using a amity Vac? I have one do aI attach to the vent on the filter base? Gas cap on or off? Any help would be appreciated I haven’t had time to drop the tank yet

 

[87cr250r]

The best place would be to put it in line between the fuel filter inlet and the lift pump. You can use the mighty vac as a pressure pump to circulate fuel up to the injection pump.

 

[Salty dog]

The best place would be to put it in line between the fuel filter inlet and the lift pump. You can use the mighty vac as a pressure pump to circulate fuel up to the injection pump.

Would that prime the fuel filter

 

[87cr250r]

It would. You're basically doing the fuel pump's job with a hand pump. Fluid flows freely through a diaphragm pump (the lift pump) in the normal direction of flow. You can put a hand pump anywhere in the loop and it will do it's thing.

With that said, I usually roll the engine on the starter with the pink wire to the IP disconnected in order to prime the fuel filter. It takes about 30 seconds.

 

[cucvrus]

To ease strain on the starter when I replace an engine and want to prime the fuel system, I remove the glow plugs. It is 10 X faster and makes everything spin much faster. Good Luck. Great time to get a visual on the glow plugs and you can bench test them. Or not. Just sharing.

 

[Mainsail]

This is how I prime the fuel system - vacuum pump connected to the extra filter boss pulls fuel through the pump and fills the filter. Truck starts immediately, stutters a bit as the post-filter lines get filled, then runs like a top.

 

[Mullaney]

This is how I prime the fuel system - vacuum pump connected to the extra filter boss pulls fuel through the pump and fills the filter. Truck starts immediately, stutters a bit as the post-filter lines get filled, then runs like a top.

View attachment 882939View attachment 882940

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Neat idea!!

 

[Salty dog]

Does anybody know the nut size for the fuel tank straps? I was able to remove the skid plate but for the life of me I cannot find a socket that fits the fuel tank straps

 

[cucvrus]

It is 11/16" they are 7/16" coarse thread. 7/16" 14.

 

[Salty dog]

It is 11/16" they are 7/16" coarse thread. 7/16" 14.

Thank you Sir, My 11/16 deep socket seems to not want to sit all the way on the nut. At least on the rear side of the straps (bumper side) I will have another look in the morning.

 

[cucvrus]

Heat the nuts and keep in mind the wires are attached and that strap is double nutted. Good Luck. Get a good deep 6-point socket that the hex drive runs the entire depth of the socket.

 

[Salty dog]

I was using a six point deep 11/16 socket, so naturally I went out and got another set of deep sockets. The 11/16 was not a go, at some point the tank has been removed. The skid plate only had four bolts holding it in place and only one strap was double nutted at one end. After dropping The tank and removing the sending unit I found the source of the problem….. rust. The inside of the tank is coated in rust and the sending unit had rust in the metal tubing. Off to order a new tank, sending unit and some hose.

 

[Salty dog]

The tank still had the original sticker on it

 

[cucvrus]

The tank still had the original sticker on it

The tank looked good to me. That was an aftermarket sending unit. I agree that you have a moisture issue in the tank, but I don't think the tank is scrap. That opening on top is big enough to get that tank clean and then evaluate from that point whether a new one is needed. Good Luck.

 

[Salty dog]

The tank looked good to me. That was an aftermarket sending unit. I agree that you have a moisture issue in the tank, but I don't think the tank is scrap. That opening on top is big enough to get that tank clean and then evaluate from that point whether a new one is needed. Good Luck.

I apologize now for asking ten million questions, the last time I had to work on a fuel system it was my 1992 YJ, and all that involved was dropping the tank and replacing the sending unit. I want to do as much as I can with the CUCV myself. The sending unit had rust inside the metal tubes as well as the metal section on the vent tube. How concerned should I be with the fuel lines themselves. I am leaning in the direction of replacing the lift pump( never did that before) as well as the filter base. When I pulled the replacement box filter I carefully inserted q tip into the inlet port and found what looked like a flake of rust. Also when I was tracing the fuel line from the lift pump, it went from the hose to metal tubing, the tubing looks like it runs on top of the frame before turning to the outside frame rail and than around the area of the transfer case it goes around to the inside of the frame( if I was following the proper line) Inside the front passenger wheel well I came across a fitting that I am not sure about. The only thing that came to mind was it is simply a junction to connect to prebent fuel lines.

 

[cucvrus]

What you are showing on the Qtips is normal crud for the condition of the fuel and fuel tank. I think the aftermarket sending unit was made of cheap steel and rusted aggressively from the normal condensation that is in the fuel tank under normal conditions. the original one was an alloy not as easily rusted. I think the fuel lines on the frame are OK as long as they are not crispy rusty looking on the outside. Also, double check the fuel return metal tubing. The rubber hose replacement is an option that you may want to make. My tip is to disconnect the batteries and change the fuel pump from the right had top side. Just loosen and lay the Gen 2 to the side. I found it easier than laying under the truck with no access and fuel / dirt falling in your face and still blindly working. Good Luck. Make sure you have everything started by hand and then tighten everything after you have all fasteners finger tight.