I bought a completer engine to rebuild. After getting it all done it will not start when cold unless you manually prime the lift pump. If you prime it will fire right up and once started you can restart easily. It is setting in the floor and pulling fuel form fuel jug. It is a 215 pump, do they have to have pressure on the pump to start? I have 3 other 12v trucks and not had any issues form them even after changing OFV or for any other reason letting pressure off the pump, but none of the other 3 are 215 pumps. Have a gauge hooked in at the bleed screw on the filter and holds 30 psi at idle (new lift pump) but bleeds off when you kill the motor. I kinked the return line after shut down and it seemed to hold pressure longer.

But my queston is does the IP pump normally need to be pressured to start?

I have searched but can't find my answer. Lots of starting issues but can't seem to find what I am asking about so any input would be helpful.

 

But my queston is does the IP pump normally need to be pressured to start?


no but it needs to be full of fuel so the IP then can pressurize the fuel.

inline pumps cant draw fuel like a rotary. they need a lift pump to survive.

could be

- your OFV is leaky
- you have some kind of air leak before the IP

 

try to squeeze the return line with a pair of vise grips .. then turn it over .. if it fires up relitivly quick .. you know its the return OFV .. if not .. internal possibility ..

Second, check that the Fuel Soleniod is opening up all the way ..

 

I have tried the vise grip on the return with same results, would not start until the fuel pressure starting building. Don't have the shut off solenoid on the motor yet. Guess I can run an electric pump to help build pressure before starting.
Engine is going in an 06 1500 and will have to put in some sort of fuel pickup out of the tank, so adding a helper pump will not be that big of a thing.

 

I think your gonna find that the stock LP is just fine .. if your loosing fuel prime .. I would serch out where its going to ..

I'm not sure but I would put a one way check valve in the return line as a way of eliminating that as a possibility .. there should be no reason for it to go back through the LP ..

 

Old lp then new lp same result. Old OFV new one same result. I am baffled.
It has a hx35 with ht3b casue that is what I have . Has 5x12 injectors, may get 14's later so will probably need an electric pump anyway.

 

what does it idle at? it may not be getting start fuel. 10mm jam nut on the back of the IP 800ish on your stand idling maybe a bit higher. try holding the throttle open just a tiny bit when ou crank it and see if it acts differently.

 

Thanks but I know that have owned several 12 valves. Something has to be leaking I just can't figure out where. Even if the OFV is bleeding off the pump should still be full enough to start. I am going to try to clamp both feed and bypass lines at shutdown to see it that makes a differance.
Thanks again for suggestions.

 

Finally some success. Last night I started the engine and set the fuel jug on top if the it when I shut it off. This morning it started right up. It must have been bleeding back down through the LP. The trucks must have a one way valve on the tank pick up.

 

.. Yup