Truck starts idles then dies

[85SmokinDetroit]

My 1985 cucv has no visible fuel leaks, I put a new ip cap seal & throttle shaft seals in the ip, after doing head studs & headgaskets. Truck will start, run idle & then die after about 4 minutes idling. And then will not restart. I’m absolutely stumped and frustrated. I’ve been trying to get it going for three weeks straight now.

 

[Barrman]

Does it speed up just a hair and smooth right immediately before it dies? That is a classic symptom of running the IP dry of fuel. His is your fuel filter, how much fuel in the tank, what shape are your fuel hoses in?

This is a video I did about how to prime and start a dry IP. I let the engine run dry if you watch it long enough. You can hear it speed up before it dies:

 

[87cr250r]

What does it take to get started again? Cracking injectors? Does it have a new lift pump? Did you get the right one? Two come up for the 6.2/6.5 but only one works. There should be no spring visible under the pump arm.

 

[85SmokinDetroit]

What does it take to get started again? Cracking injectors? Does it have a new lift pump? Did you get the right one? Two come up for the 6.2/6.5 but only one works. There should be no spring visible under the pump arm.

Cracking some part of the fuel system and cranking it’s definitely losing prime in the fuel system the fuel pump is good it’s a brand new Air dog 5g it can push 200pgh if needed. I keep hearing air seep around the return lines on the injectors could that be letting air in the system and making it lose prime

 

[Barrman]

The return lines could be removed and the engine will run just fine. It will make a huge mess though.

Putting a clear hose for the top of the IP return will let you watch for air bubbles to verify air is getting into the IP fuel supply. But, since you are running dry you already know that.

The video I posted shows an electric pump under the truck bed. I put that pump on when I still was running the stock 230 engine. The sock in my tank tended to clog and after being stuck on the side of the road a few times the electric pump allowed me to get rolling again without draining the batteries. The pump I bought had a screw in fuel filter.

I never had trouble running the 230 or the Big Block 396 that replaced it. But as soon as I had the 6.2 in there I started running the IP dry. Even with the electric pump on! It was driving me nuts. I finally traced the air getting in to the threads on that screw in fuel filter. No teflon. That small of a leak on the suction side of a diesel lift pump can and does cause the IP to run dry.

With that in mind. What do the hoses above your fuel tank look like, the frame rail hose in the middle of the truck and the hose going to the lift pump?

 

[85SmokinDetroit]

The return lines could be removed and the engine will run just fine. It will make a huge mess though.

Putting a clear hose for the top of the IP return will let you watch for air bubbles to verify air is getting into the IP fuel supply. But, since you are running dry you already know that.

The video I posted shows an electric pump under the truck bed. I put that pump on when I still was running the stock 230 engine. The sock in my tank tended to clog and after being stuck on the side of the road a few times the electric pump allowed me to get rolling again without draining the batteries. The pump I bought had a screw in fuel filter.

I never had trouble running the 230 or the Big Block 396 that replaced it. But as soon as I had the 6.2 in there I started running the IP dry. Even with the electric pump on! It was driving me nuts. I finally traced the air getting in to the threads on that screw in fuel filter. No teflon. That small of a leak on the suction side of a diesel lift pump can and does cause the IP to run dry.

With that in mind. What do the hoses above your fuel tank look like, the frame rail hose in the middle of the truck and the hose going to the lift pump?

Thanks a lot barrman I’m a young guy first time messing with one of these or a diesel at all, I hooked my “Air Dog 5g” lift pump up and it’s still running dry so I’ve determined somewhere around on the suction side is making the fuel leak being I watched the air dog pump fuel and at my clear return line it was pushing consistent air bubbles from inside the IP whole reason I hooked the fuel pump up was I figured the mech lift pump for whatever reason couldn’t keep up in the volume anymore, again wrong so it’s at simple as I have a very small fuel leak somewhere on suction side, I’ve been getting super frustrated with this truck lol. But I figured it might have been the return lines, now I know otherwise. Much thanks I’ll be checking for small leaks absolutely everywhere. Any advice on other places to be checking other than filters because I’m running 2 one on the brand new lift pump and a second on the firewall similar to the one in your video you posted previously also here is my truck it’s a 85 m1008