96 F250 Hard Start Hot with Low Icp

PowerSToKed · January 8, 2011

Got a 96 here that starts cold and will run all day, will not restart after engine is warm. KOEO ICP Voltage - .22v, during the concern (engine spinning) ICP 200psi / .85v, IPR 23%. I replaced the IPR valve and the concern is still present. I am going to block off the lines to the heads to check for leaks in the morning - Just wondering if anyone has seen anything else that could cause this concern.

Bruce Amacker · January 8, 2011

I'm a little surprised the IPR command is that low during a low ICP crank, usually it's considerably higher. I still would suspect leaking injector o-rings. Uppers will give your concern, centers will give your concern plus oily fuel. Is the fuel dark or gray in the filter? You can also pull the valve cover with it running and look for telltale spraying from the uppers. What's IPR command at a hot idle? It should be 9-11%.

Make sure you use the correct IPR for the pump- '95-96 should take the edge filter design.

If you don't find any leaks I might try grounding the IPR return wire while it's cranking (no start) hot. That 23% bothers me a bit....

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