95 Bronco - No start - new, previous high idle

I have a 110K mile full size Bronco. I have every intention of driving it until Ford brings back this excellent vehicle.

I have had great service from this vehicle, with only minor problems until now(replaced radiator, 2 core plugs and A/C compressor). The worst problem I’ve had have occured when taking it in for Dealer servicing.

My current problem is engine will not start. Starter turns engine over, but engine does not start. The only thing I have noticed is lack of priming sound from intank fuel pump. There was no other indication of a problem with engine starting in all the years I’ve had this vehicle. However, recently I have encountered a problem with engine idle (1,500 rpm, 1,100 when in gear), after replacing A/C compressor. This is an intermittant problem, which occured at random intervals, not related to any particular time, heat or traffic.

Obviously, the 1st issue is to get the truck to start, then take it in to finally resolve the high idle problem. My only excuse for not having that address earlier is distrust of Ford dealer servicing.

I did have the intake maniford cleaned, check for vaccum leaks and replaced air filter - with no improvment. This no start problem prevents any further investigation.

Maybe a relay or other electrical issue keeping the fuel pump from running. Check for voltage to the pump.
Idle issue could be idle air control valve (IAC) or its wiring, or a vacuum leak.

I replaced the IAC, TPS and checked for burned dash fuses. so far no love. I did check the under hood relays, but “mapping” - which relays, fuses are responsible for what, are not obvious. So far unable to find schematics that map relays or fuses in the under hood area.

Still working to find a solution, I am working with another source, but diagnostics are down to the basic level…interface testing to isolate components.

Any idea of a source for relay mappings? I’ll also see if scanner will register any codes, even though I have disconnected battery. I’m wonder if codes are persistant?

Well, as I suspected, dreaded and hoped to avoid - the issue root cause is the Fuel Pump. I have to dump a 1/2 tank of fuel, drop the tank and worse - OEM integrated intank pump, sensor assembly is not just expensive, its Very expensive!

Unable to find a reason for the failure, maybe its number just came up, although. It is possible to reduce the cost by replacing the pump and retain the rest of the assembly, all it takes is a little extra time, snip a few wires and badda bing - reinstall the patched and rebuilt unit. I’m taking the easy, more expensive out.

The IAC did need to be replaced, even though it was not contributing to the no start problem. The interior plunger was stuck, which prevented the actuator from modulating the air flow bypass. Cleaning it had no effect for the price it was better to replace it anyway.

TPS, was not a problem. That was money wasted as was replacing the fuel pump relay.

There was no test to verify function of relay, so substitution was the my solution. I guess I could have swapped another relay (there are 4 under the hood, all have the same part number).

Lessons learned, are often prefaced by chaotic thrashing.

Thanks for the comments.