Truck keeps losing it's prime

[corvette9]

I have 2 CUCV's with the same problem. Never had any problems with starting the 1028 or the 1008. Then out of the blue they both loose prime over night. I tried a new lift pump on one, no help. Changed all rubber lines on both,no help. Changed the fuel filter on mine, the 1028 and it was fine for about a week. Put both trucks on a lift and can not find any leaks ,no wet fuel lines.

I talked to my diesel mech. that dose all the work on my tow trucks and he told me to try opening the vent for the tank. So I pulled the rubber plug off the vent line behind the cab And it worked on the 1028 and the 1008. Problem is as soon as the weather warms up the fuel expands and pours out the vent.

I put the plugs back on. Problem comes back. Both trucks run perfect once they start as they always have.

I'm out of ideas. I was going to try a new IP on the 1028 but have a hard time with two IP going bad at the same time.

Where do I go from here?

 

[cucvrus]

Is this from cold start? How do they start the rest of the day after the fuel is re-primed? And you checked the round plug behind the fuel filter?

 

[cucvrus]

Quick tip. No expense or redesign needed. I had this problem on my Son's M1028A1 and a few of the CUCV plow vehicles. I removed the pressure sensor. Not needed anyway. I put a self tapping screw in the hole in picture 2. I checked the seal of the screw with a vacuum pump. It held. I filled the entire cavity with Permatex : The Right Stuff. And the problem was gone. And it has been gone for 2 years on a few and my Son's M1018A1 still starts and takes it's daily beating with out missing a beat. Give it a try. It must be vacuum tight. Good Luck. That pressure switch is only connected to the military diagnostic plug under the dash. Unless you plan on keeping Dude in museum condition I would do this and give it a try. you have nothing to lose. I think it will be a WIN. Please report back.

 

[corvette9]

Only from cold overnight start. After that they start with a bump of the key.

 

[corvette9]

So your saying unbolt the filter housing from the firewall and block that black round plug. Or is that the front under the filter?

 

[cucvrus]

That picture is the fuel filter base. It is bolted to the fire wall with 3 - 3/8" bolts. you will need a 1/4" nut driver (fuel line clamps) and a 9/16" socket and remove the entire fuel filter assembly. Remove that foam/plastic disc (2 wires) behind the filter. About the size of a half dollar. Scrap that. Not needed. Picture 1 nice clean oil free surface. Picture 2 worthless defective piece. Only needed if you are in a show of museum quality. Dude is NOT a virgin by any means. Been there done that many times. Has been driven coast to coast at Ludacris speed. Dig the plaid shoes. Rodney Dangerfield edition. Kid's. I have all the stock filters on all my units. I have few problems if any with them. That one has been on Dude since new and over 170K miles. I think that passed the endurance test. No need to redesign. Report back. I think this will help you out. Sure keep you from replacing the injection pump. Good Luck.

 

[corvette9]

Got it

 

[Mainsail]

Put both trucks on a lift and can not find any leaks ,no wet fuel lines.

Fuel isn't leaking out; air is leaking in.

Try parking nose-down and see if the problem corrects.

Either way, get a spin-on fuel filter and the problem should go away.

 

[cucvrus]

I knew I had this picture. Remove this piece. Screw the hole shut. Test with vacuum pump. Sealer (Right Stuff) is optional. I preferred as a secondary seal. You can reinstall the same fuel filter and be on your way. Down time about 1 hour for us older guys and cost is 1 screw self tapping. https://youtu.be/3YmMNpbFjp0 I am hoping. Or https://youtu.be/897jlnmTYqE which I doubt. It is 100% worth the try if you have double checked everything. I assume you looked at the steel lines under the rear of the cab. They are suspect to wear from rubbing also. And vacuum check the lines from the tank to the fuel filter. I doubt but possible. Please report back. Sorry the Dude has let you down.

 

[MarcusOReallyus]

Okay, the video clip was a Master touch, but the shoes???

That's just wrong.....

 

[cucvrus]

corvette9 any updates? Or am I rushing the old guy? I will remain calm. just check in on any progress or improvements. Dude deserves immediate attention.
https://youtu.be/PcRyjkYdDxM

 

[corvette9]

I won't get to work on him till Sat. That's the only free time I have. When I get home after being here all day I'm shot.

 

[Mainsail]

I won't get to work on him till Sat. That's the only free time I have. When I get home after being here all day I'm shot.

Do you have ramps or any other way of parking it nose down? That's a free and no-effort troubleshooting tip.

 

[corvette9]

I can park it in my back yard. I'll try that today.

 

[corvette9]

I just parked it facing downhill. CUCVRUS is correct. That filter base should not take 10 min. to remove. I'll try and start it in the morning and see what happens. I'm going to pull the filter base and plug the sensor no matter what.
I'll report back soon.

BG

 

[MarcusOReallyus]

corvette9 any updates? Or am I rushing the old guy? I will remain calm. just check in on any progress or improvements. Dude deserves immediate attention.
https://youtu.be/PcRyjkYdDxM

Okay, that makes up for the shoes!


By the way folks, a loose prime would be the opposite of a tight prime, whatever that is. Loose rhymes with goose, moose, Bruce, juice, and (to keep this on topic) deuce.


Lose is what you do in Las Vegas. It rhymes with booze, snooze, shoes, and cruise.

 

[dougco1]

corvette9 any updates? Or am I rushing the old guy? I will remain calm. just check in on any progress or improvements. Dude deserves immediate attention.
https://youtu.be/PcRyjkYdDxM

Rick, where do you come up with these crazy things? Don't you ever sleep? Work a full time job -Work on CUCVs - Work on posting every day - And still have time to find these videos.

 

[MarcusOReallyus]

Rick, where do you come up with these crazy things? Don't you ever sleep? Work a full time job -Work on CUCVs - Work on posting every day - And still have time to find these videos.

It's easy if you're crazy!

 

[corvette9]

Ok. My 1028 has been parked facing downhill for two days now. I got in this morning let the glow plugs cycle and he fired right up like it should. So this tells my what. I'm going to remove the filter housing on Sat. and remove and plug that sensor Cucvrus told me to do. Any other ideas?

 

[Mainsail]

Ok. My 1028 has been parked facing downhill for two days now. I got in this morning let the glow plugs cycle and he fired right up like it should. So this tells my what. I'm going to remove the filter housing on Sat. and remove and plug that sensor Cucvrus told me to do. Any other ideas?

It tells you that you have a leak, likely in the filter somewhere. Air was leaking in, but parked downhill sort of seals the air leak in with a fuel leak out, if that makes sense.

Plug the sensor or