Continued Fuel system issues

[85SmokinDetroit]

Truck Starts runs for 3ish minutes then dies from running the IP dry, there’s air in the fuel, whole fuel system is brand new from the fitting on the DB2 pump to the sending unit to the tank, I noticed the hard metal injector fuel lines are rusty and probably not getting the best seal & leaking. Would those leaking cause air to get into the fuel system or are they in the same boat as the return lines and the motor will run with them leaking. And won’t put air in the fuel system. Any help I cannot find any leaks in the system put oil based UV dye in fuel and can’t see any anywhere, filters are new, The Electric Air Dog Lift pump is new, no mechanical LP anymore, seals inside the IP are new I drove the truck into the garage to do headstuds and it’s been there for 4 weeks nearly 5 now, any help would be appricated thanks.

 

[cucvrus]

Based on what you wrote I would not know where to begin to help you. The repair manuals are worthless at this point with all the modifications. The CUCV is stock form was a simple design and easy to diagnose. Now I don't think I can help you. And leaking return lines will allow air into the fuel system. What is an Air Dog lift pump? Never mind I looked at it. Good Luck and Be Safe.

 

[adf5565]

Have you looked at the sock filter on the sending unit in the tank? Those can get pretty dirty

 

[LT67]

Have you looked at the sock filter on the sending unit in the tank? Those can get pretty dirty

^^what he said..

 

[Wreckclues]

Did you say the pickup tube in the tank is new?

 

[85SmokinDetroit]

Have you looked at the sock filter on the sending unit in the tank? Those can get pretty dirty

Yes I have

 

[85SmokinDetroit]

Based on what you wrote I would not know where to begin to help you. The repair manuals are worthless at this point with all the modifications. The CUCV is stock form was a simple design and easy to diagnose. Now I don't think I can help you. And leaking return lines will allow air into the fuel system. What is an Air Dog lift pump? Never mind I looked at it. Good Luck and Be Safe.

Yup

 

[85SmokinDetroit]

Did you say the pickup tube in the tank is new?

It’s all new, it’s just an air leak somewhere, that I’m apparently to clueless to find even with UV dye in the fuel

 

[87cr250r]

The air leak is probably the throttle shaft on the DB2 pump. When mine leaked the truck would start and idle fine but die after driving 50 feet. I never did let it idle for 3 minutes so I don't know if it would have died without driving it. It would start again after 30-60 seconds of cranking and run fine for the rest of the day. No visible leaks.

 

[antennaclimber]

I would directly supply fuel to the IP with a gravity feed source.
Or, try using a known good fuel pump and feed the IP from that.
This will test the IP to ensure that it is functioning correctly.

If it does stay running, then test the electric fuel pump to ensure that it is delivering fuel to the IP.

I had a M1009 that had the same symptoms as you described, it turned out to be the fuel pump and the IP were both defective.

 

[85SmokinDetroit]

Based on what you wrote I would not know where to begin to help you. The repair manuals are worthless at this point with all the modifications. The CUCV is stock form was a simple design and easy to diagnose. Now I don't think I can help you. And leaking return lines will allow air into the fuel system. What is an Air Dog lift pump? Never mind I looked at it. Good Luck and Be Safe.

It’s still a stock design fuel system just converted to a Lift pump and Napa fuel filter base on the fir

Based on what you wrote I would not know where to begin to help you. The repair manuals are worthless at this point with all the modifications. The CUCV is stock form was a simple design and easy to diagnose. Now I don't think I can help you. And leaking return lines will allow air into the fuel system. What is an Air Dog lift pump? Never mind I looked at it. Good Luck and Be Safe.

The air leak is probably the throttle shaft on the DB2 pump. When mine leaked the truck would start and idle fine but die after driving 50 feet. I never did let it idle for 3 minutes so I don't know if it would have died without driving it. It would start again after 30-60 seconds of cranking and run fine for the rest of the day. No visible leaks.

Mine were leaking, I put New o rings in on the shaft, still having issues tho lol.

 

[85SmokinDetroit]

I would directly supply fuel to the IP with a gravity feed source.
Or, try using a known good fuel pump and feed the IP from that.
This will test the IP to ensure that it is functioning correctly.

If it does stay running, then test the electric fuel pump to ensure that it is delivering fuel to the IP.

I had a M1009 that had the same symptoms as you described, it turned out to be the fuel pump and the IP were both defective.

What gets me though is I drove the truck into the garage to do the headstuds, but appricate the advice man I’m gonna try the gravity feed first to see if it’s the IP.

 

[nyoffroad]

I'd do a test like AC said and or use a known good pump to supply the IP. If that works you know the problem is in the tank/lines/filter or the electric pump. Just a quick thought here, are you sure the electric pump is facing the correct way? Sounds stupid but ya never know, always check the easiest first.
Failing all the above try removing the filler cap and using a bunch of rags and a blow gun pressurize the fuel tank, you only need a few pounds of air pressure! Have a helper look for fuel leaking from hoses and fittings. It may take some time to push fuel up thru the dry lines but anyplace it is sucking air fuel will leak.
You have an aftermarket electric fuel pump (if I understand correctly) all the electric pumps I've ever delt with needed to be mounted NEAR the tank and some had to be at or below the tank! They push fuel unlike the stock lift pumps that suck fuel.

 

[85SmokinDetroit]

I'd do a test like AC said and or use a known good pump to supply the IP. If that works you know the problem is in the tank/lines/filter or the electric pump. Just a quick thought here, are you sure the electric pump is facing the correct way? Sounds stupid but ya never know, always check the easiest first.
Failing all the above try removing the filler cap and using a bunch of rags and a blow gun pressurize the fuel tank, you only need a few pounds of air pressure! Have a helper look for fuel leaking from hoses and fittings. It may take some time to push fuel up thru the dry lines but anyplace it is sucking air fuel will leak.
You have an aftermarket electric fuel pump (if I understand correctly) all the electric pumps I've ever delt with needed to be mounted NEAR the tank and some had to be at or below the tank! They push fuel unlike the stock lift pumps that suck fuel.

This is an aftermarket Airdog-II 5g lift pump it’s a known and good pump also setup correctly on the truck, facing the correct way. I’ve also fed the pump off of a 5 gallon tank of fuel after even checking the tank Sending unit & sock out pretty thoroughly, I’m thinking my best bet it trying to gravity feed the injection pump fuel and see if it still gets air in it, any thoughts, basically making these posts to see if anyone could tell me if the injection pump could pull air in since most of the seals are designed to leak out not in, because I’m thinking I may have messed something up when I did the throttle shaft seals. But to pressurize the system I have to wait until next weekend, a buddy is getting a price of equipment that can do it & won’t blow the filters apart.

 

[Wreckclues]

it’s just an air leak somewhere, that I’m apparently to clueless to find even with UV dye in the fuel

Does that model have a primer pump? I just rebuilt the one on my M813 to address a similar, if not more pronounced issue.

 

[85SmokinDetroit]

Does that model have a primer pump? I just rebuilt the one on my M813 to address a similar, if not more pronounced issue.

It does not.

 

[WWRD99]

Have you tried to unhook the fuel line going to the ip after the filter and see if fuel comes out with good flow? Gotta be something weird. I've had new parts or thought they were good parts not work like they should...possibly hook a pressure gage to it to?? The electric pump should prime the system pretty fast. Is the shut down solenoid in the ip goin nuts? Like losing power when it shuts off? The big red wire on top...might be a key ignition thing??