Fuel Prime Q

[Gravelguy413]

Still having an Issue with full mechanical E7 fuel prime bleeding down over night and causing long crank times. Have replaced fuel return line and also lift pump no luck. Truck idles nice but seems to have a slight miss operating. Somebody earlier mentioned a possible bad injector. Would one bad injector cause long crank times? Also somebody mentioned a possible bad check valve. Where is this valve located?

[h67st]

The check valves are in the lift pump; if you replaced the whole pump that would fix them. My hand primer pump was bad, causing loss of prime but maybe you already replaced it. I found my leak by removing the lines at the fuel tank, plugging them off, and putting 10 psi air into them...fuel started seeping out of the primer so that showed where the problem was.

[OldRedMack]

Check your fuel filter stand for cracks, took us 2 years to find that problem on a truck. 

[John3406]

Should be a check valve in pump. I think its called an overflow valve. Should be up towards the top and side of pump but i cant remember without looking at the pump

[MACKX]

If it’s a Bosch 7100 pump the overflow valve will cause extended crank times.... it’s on the top outside of the pump as John said earlier .... take it out and see if shakes like a rattle if it does it should be working ... you can take the end plug out and remove the spring and stretch it out to buy a little time before you get a new one if need be....  definitely check for air leaks also 

[Gravelguy413]

Great thanks everybody