Excessive cranking needed to start 460 Ford

[dlflyer]

We have a 1990 Safari Serengeti with a Banks system and Gear vender overdrive.  The big problem right now is (and always has been but its really starting to bug me)  the electric fuel pump will not turn on until you crank it enough to get oil pressure.

I understand the concept. The trouble is it takes a long time for the fuel pump to deliver enough fuel to start the engine.  So I end up doing a lot of cranking. I crank until about 60psi is reached stop cranking and let the fuel pump run until just before it shuts it's self off at 10psi then crank again.  I have to do that about 3 times. That's a lot of cranking. 

If the engine is hot it is even worse. Pressure bleeds off real fast almost impossible to start. Must times I just leave it running when I stop. I want to bypass the shut off relay with a momentary switch. Hold for fuel pump to run (start engine)  release for normal operation. Anyone know where the fuel pump relay is or could I use the oil pressure switch circuit or any other ideas? 

The old girl just rolled over 40,000 mi. We are from Michigan and are in Yuma Az. right now.

[jmerritt]

There isn't any shut off relay, at least not on my 1988 Fleetwood Limited on the John Deere Chassis. The oil pressure switch for controlling the fuel pump and the oil pressure sending unit are both located on the back of the motor on the intake manifold.  Both work on the sending unit being grounded and a single wire to each sending unit. My wiring diagram shows the red/yellow wire is for the shut off and the white/red is for the pressure gauge.  Switch would need to be wired to ground on one side to the r/y wire and straight through circuit on the r/y wire on the other side of the switch.

John

[Froggy1936]

dlflyer, Sounds more like fuel pressure is bleeding off too fast,Fuel is being returned to the tank as fast as it is pushed up to the engine .   Find out what controls fuel pressure .It is controlled in the return line  Or check the fuel rail  pressure with a gauge , You will need some Ford fuel injection syestem information to figure it out  . Frank

[Stripe]

Is it possible the gas cap isn't on tight enough and he's losing pressure because of that?

[DaveVA78Chieftain]

The Carburetor John Deere chassis version does not use a Fuel Pump Relay.  During engine START, voltage to the Fuel Pump is provided from the "I" terminal of the starter relay via a fusible link.  Power to the Fuel Pump in RUN is directly from the oil press switch.
I have a hunch the fusible link (Circuit 302, orange wire) is up in the area of the voltage regulator (Passenger side near the radiator support bracket) .

The EFI John Deere chassis version does use a Fuel Pump relay however it does not use the oil pressure switch to provide power to the pump.  The relay is controlled by the ECM.

John Deere manual is available in the site store: http://www.classicwinnebagos.com/forum/index.php?action=store;cat=43

Dave

[TripleJ]

Out of curiosity is the OP engine fuel injected? I assume it is because of the year but as has been shown it makes a difference with the diagnosis. For instance, with efi I'm pretty sure there should be a prime cycle at key ON that is not dependant on oil pressure

[dlflyer]

Thank you for the comments. As always when you have a problem there is a reason for it. In my hast to do a quick fix I found the REAL problem.  The carb was leaking fuel. Yep dripping right out the bottom of the front bowl (my lovely wife kept telling me she smelled gas every time we shut down the engine). Something told me to pull the air cleaner off and have a good look around. I had only been removing the top and looking down in the top of the carb. On the road is no place to have to get anything fixed but I had no choice this thing was pouring gas and running bad. took it off had it rebuilt (ouch ) but was happy with how it worked after. I know my starter motor is happy too. Touch the key and she is running. No more excessive cranking. Plus added almost one mpg.

[Stripe]

Plus added almost one mpg.

That's always a good thing..