Hard start

blackf3504dr · 02-05-2011, 07:19 AM

I have a '92 HR on a '91 F53 chassis that has been starting fine until recently (once started it runs fine). It spins over great but unless you "cycle" the fuel pump a few times by turning the key off and on it won't start... My question is, does this sound like a fuel pump problem, fuel regulator or is there a check valve to stop the loss of fuel pressure that has failed ? I took it in and the mechanic verified low fuel pressure on start up... Any advice is welcomed.

fletch460 · 02-05-2011, 10:19 AM

If it is running fine under load I dont think fuel pump is problem. Sounds like a partially clogged filter. Dont know where it is located on your rig. Cheap fix. Didnt say what engine, but someof the older engines had a filter at base of carb if you have one.
Good luck, Fletch

subford · 02-05-2011, 11:35 AM

Most likely it is the fuel pump or to be more exact the check valve in the Fuel Delivery Module (FDM) that is inside the fuel tank. The fuel pump is also inside the FDM.

But before you take the tank down or cut a hole in the floor check the Fuel Pressure Regulator (FPR) by pulling the vacuum hose off and turn the key on and off about three times. If fuel comes out of the nipple on top of the FPR it is bad.

It does not sound like a Fuel Filter problem but a bad injector can also leak fuel from the fuel system while not running.

The FDM is also sometimes called the Fuel Delivery Assembly:

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LVJ58 · 02-05-2011, 01:58 PM

I would check for a faulty fuel pump relay first

blackf3504dr · 02-06-2011, 04:26 AM

Thanks subford. It does run good (once it starts) which led me to believe it's not the fuel pump. I don't think it's the relay because the pump has power and I can hear it cycle when the key is turned on and it (the pump) runs with out a problem, also the fuel filter would cause a problem when running and it doesn't show any loss of power or hesitation. Oh, it's the 460 FI (7.5 if you prefer liters over cubes).... Right now it's going to have to wait for me to check it out as it's being used as "guest quarters" for my wife's sister and her husband
Thanks all.

subford · 02-06-2011, 07:22 AM

Yes it is very common problem with the fuel draining back into the tank when the engine is not running and as I say most of the time the high pressure check valve in the FDM is the cause.

Of course you can live with it being that way as you know by turning the key on and then off for about four times before you try to start the engine to fill the fuel lines the engine will then start right up. It should cause no other problems for you as the valves only purpose is to keep fuel in the fuel lines while the engine is off.
As long as you can hear the fuel pump run each time the key is turned on the fuel pump relay is just fine (OK).

blackf3504dr · 02-07-2011, 04:39 AM

Quote:

Originally Posted by subford

Yes it is very common problem with the fuel draining back into the tank when the engine is not running and as I say most of the time the high pressure check valve in the FDM is the cause.

Of course you can live with it being that way as you know by turning the key on and then off for about four times before you try to start the engine to fill the fuel lines the engine will then start right up. It should cause no other problems for you as the valves only purpose is to keep fuel in the fuel lines while the engine is off.
As long as you can hear the fuel pump run each time the key is turned on the fuel pump relay is just fine (OK).

Thanks subford, is the FDM a serviceable part, or does the whole pump have to be replaced ?

subford · 02-07-2011, 05:46 AM

Quote:

Originally Posted by blackf3504dr

Thanks subford, is the FDM a serviceable part, or does the whole pump have to be replaced ?

As you know as in the other thread that you have posted in:
F-53 Fuel Pump Change Pictures
The whole unit is replaceable but you can get away with just replacing the FDM part.

There is also a new stile pump from Ford as in this attached TSB 97-23-9.

blackf3504dr · 02-07-2011, 06:11 AM

Quote:

Originally Posted by subford

As you know as in the other thread that you have posted in:
F-53 Fuel Pump Change Pictures
The whole unit is replaceable but you can get away with just replacing the FDM part.

There is also a new stile pump from Ford as in this attached TSB 97-23-9.

It's progressively gotten worse since then... As long as I have the pump out I may as well spend the money and replace the whole thing.... I don't suppose you want to come show me how it's done ?