We have a 91 F350 with the 7.3. We have a fuel leak, appears to be coming from the fuel pump, hoses possibly. Sometimes when you crank the truck it idles ok, then idles real rough and shuts off. It then takes a bit to get it cranked again. Typically after this episode when it is re-started you have to keep it idling high until you feel it even out and can then put it in gear. We bought the fuel pump, but now hubby is having doubts that the pump is leaking. Any ideas? Anyone else have this problem?

 

Ok,so 1st thing to clear up is what your refering to as the fuel pump.Are you talking about the lift pump down on the side of the block or the injection pump which sits on top of the engine.If the lift pump is leaking it should be coming from the weep hole,if thats the one you bought look at the new one for exact location of the little weep hole.If no sign from the hole then re-tighten the fuel lines on all clamps.Can you see fuel on the ground or do you just smell fuel?
It sounds more to me like the return lines and 0-rings may need to be replaced.Are they orignal? If the rubber hoses are grey in color,they are original.How many miles on the truck?Is the injection pump orignal?

 

I did not crawl under it, to see if they are original. A lot of the equipment is. The truck has 245,000 and has been great. Had some minor stuff done when we bought it in july, oil change, had a small leak in the transmission cooling line, we do have a small oil leak, but our mechanic said it was not bad, it does not burn oil.
Hubby said when he looked last night that he did not think it was the pump. Forgive my idiotness here, yes I am female but not a total mechanical dummy. THe part that is leaking is under the "alternator", I am assuming that is it, the belt runs around it and it has the "fan" type blade on the outside (sorry for my relative stupidity) There is a flattened round piece directly under that with two hoses coming off (from underneath) that is where the leak is. Hubby said the fuel pump is actually behind there and a little lower.
We do have a Haynes diesel manual, but not a Ford F 350 diesel manual from Haynes, tried to find one yesterday to no avail, guessing will have to order one.
Yes I could take this to my mechanic, but I owe him about $1400 from my other two vehicles and refuse to rack up anymore bills.

 

Ok,the part you described with the 2 lines comin off it is the lift pump(fuel pump).If you have the new one look for the weep hole in the bottom of the pump so you/he will know where to look at the one on the rig.It could just be a line leaking.Also check where the line comes from that pump up to the filter,it could be leaking on the fitting to the filter and runnin down the line,dripping from the pump.
The Haynes Techbook 10330(1736) is the one i have,it covers these engines pretty good.I also have a Chiltons book,Pick-ups and Bronco 1987-96,it also covers the diesel,the book number is (8136)26664.

 

Thanks! This is very frustrating. Nothing seriously wrong with this truck, just minor irritating, hair pulling things. I am lucky in the fact that i am not a "dumb" female. First thing my daddy did when I got my licsense is teach me how to change a tire and change the oil.
Over the years I have always been able to figure out and work on minor things.
Now if we could just figure out brakes on the stupid Chevy Lumina Van (the one I hate anyway)
Thanks for the help, will probably go ahead and get new hoses too, small price to pay to be sure.
Do you think this will cure the idling problem? To me it acts as if it is running out of fuel, which logically would make sense due to the leak.

 

If its leaking then the volume from the pump will be low and that could cause idling probs,if its leaking on the line before the pump then when its running its sucking air wich will deff cause probs like your having.

 

Thats it, acts like it is sucking air. Sometimes hard to crank after and episode. I think we will go ahead and replace the lines and all. I am sure the cost will be minimal to be sure that we fix the leak.

 

Is there any signs of fuel around the injectors?If the rubber return lines on the injectors are grey in color (original) then you should also pick up a return line kit.That will also cause the same probs you are having.The kit comes with new hoses,o-rings(they go under the plastic caps on the injectors,2 per injector)and copper washers that you wont use unless you remove a injector.

 

No leaking around the injectors. I did check the hoses coming from the pump and they are black, so must not be original, but with the mileage does not surprise me that they are leaking. It only leaks when cranked so that is why we started thinking fuel pump.
I love my truck so if it was serious I would def take it to the mechanic, think this is just another irritating little thing that needs fixed.
This is the first Dually I have ever owned, but I have driven trucks from the time I started driving. Everyone thinks this is hubbys truck, they are wrong it is mine.

 

We figured it out, the Fuel Pump to Header Tube has a hole in it.
Calling to get a new one today.

 

You might also be interested that the starter is very sensitive to heat caused by long cranking episodes. Dont over crank on the starter. The fuel from the tank to the lift pump (runs off cam lobe like gas engine) is vacuum and from the lift pump the fuel is pressure (about 7 psi) to the injection pump (has all the lines running from it to each cylinder) and those steel lines are high pressure lines. The plastic caps on top of each injector is the return fuel system and they have o rings beneath them which dry out and cause leaks. Some of which you wont see but may cause problems drawing air into the fuel system. Hope this helps. Good luck and keep us posted.

 

I never turn it over for very long. If it won't start I don't keep trying. Had to tech hubby about this , but he learned quick.
So far all the repairs on this truck have been minor. I really have no complaints, it just sometimes gets a little frustrating when a lot of "little" things go wrong at once.

 

Glad you found the problem,good luck with the dually.