1995 Ford F350 - 7.3L Diesel Transfer Pump

[RODNEYY]

This truck has a mechanical fuel (transfer) pump.

Is the system suppose to hold fuel pressure when vehicle is off? It take about 15 to twenty cranks to get to 44lbs. As soon as we stop cranking, it drops fast to zero.

[steven kiser]

A bit confused here. Transfer pumps move fuel from tank to tank. Lift pumps supply the injector pump. If you're suffering from a long crank before start up look into oil pressure as well as fuel.

[Tim Martin]

This truck has a mechanical fuel (transfer) pump.

Is the system suppose to hold fuel pressure when vehicle is off? It take about 15 to twenty cranks to get to 44lbs. As soon as we stop cranking, it drops fast to zero.

First of all, Welcome to the Forum! Glad to hear from ya.

May I suggest that we be given more info so we know exactly what direction to steer your diagnosis. Especially what symptom is to be addressed and corrected. There are some exceptionally good diesel guys that are on this forum and will be happy to share their expertise with you.

[RODNEY]

According to my local Ford Dealer, the mechanical fuel pump that sits on the intake manifold is called a transfer pump, it confused me to to. This is my first experience working on a 7.3 power stroke. I think I have more than one problem, but the first is the fuel pressure. Truck will not start, when cranking engine it take about 10 seconds for fuel pressure to top out at 44lbs. When it reaches 44lbs it will then drop back down to 36lbs while i am still cranking. It will keep going to 44llbs and then drop to 36lbs. But as soon as i stop cranking the pressure drops to zero within seconds

[Tim Martin]

So, the main issue is a no start. Ok.

The fuel pump in the valley between the cylinders heads is correctly called a fuel transfer pump in that it transfers fuel from the tank to the fuel injectors at a certain pressure.

One of the first things that I think of is the fuel pressure regulator on the drivers side of the fuel filter housing. These things are notorious for not functioning when they are needed. Secondly, a badly restricted fuel filter can create similar issues. There is where to start. Also, the fuel pump is also suspect for erratic fuel pressure. But check the regulator and filter first. If it gets to the point of pump replacement get some input from us guys before you do this.

[RODNEY]

I have replaced the fuel filter. I will check the regulator, I am also going to replace o'rings on return lines at cylinder heads. Is the system suppose to hold pressure when vehicle is not running and if so how much. Thank you for your help, it is greatly appreciated.

[Tim Martin]

Well, I myself do not recall of ever checking if these mechanical fuel transfer pumps will hold pressure after the engine stops rotating. Perhaps someone else would know that answer.

[RODNEY]

Same truck different problem. I will start from beginning. Truck was towed for no start, I found no oil pressure coming from high pressure oil pump. I replaced IPR, still no oil pressure, replaced high pressure pump. I Assumed i would then have pressure and did not retest. Truck would still not start. That when i started checking fuel pressure. This morning just for giggles I decided to check oil pressure to injectors again and low and behold there was none. I defected out the IPR i just put in with another new one. Now high had 2400 psi on both high pressure lines, I then connected them back to heads and truck started. It ran for about half hour before I shut it down. Went back to start it and would not start. I have no oil pressure going to injectors again. What could keep taking out IPR's ??????

[brianp87]

Whats the % of ipr show on the scanner? What about voltage lose to the ipr? Can the icp pump be powered up?

[Tim Martin]

Oh. Ok. Now we have us a totally different issue. Ahhhh. Check for battery voltage on the red wire at the IPR when the key is in the run position. Should be battery voltage there. If it isn't, then there is a voltage supply issue - possibly a relay. If there is voltage on the red wire, then let the IPR wiring connected and hook up your DVOM on the orange wire and check for duty cycle. See what is there.

[RODNEY]

I had my other tech looking at it, after it would not start, and i had incorrect info. There is oil pressure, If I take disconnect both high pressure oil lines from heads and put mechanical gauges on both lines at same time, there is 3000 psi at both lines. When passenger side line is reconnected to head and gauge on drivers side line there is 3000 psi on gauge on drives side line. When gauge is put on passenger line and drives side line is connected to head there is no pressure. I given info yesterday by customer that was not told to me before. When truck first would not start he gave it a shot of ether in it to start it, it started and ran fine. That evening it would not start and he gave it another shot of ether and it started again, he then took it to another shop. They could not get it to start and diagnosed drivers bank injector o'rings. After installing o'rings the truck would not start and customer towed vehicle out of that shop. The truck started and held good oil pressure in both heads yesterday, then would not start and will not hold pressure in drivers bank.

[liljoe]

Not too many places for it to go, pop the valve cover off and use air pressure to pressureize that bank and you should be able to see wher it is coming from that way.

[RODNEY]

I now have a different problem with this truck. Once again I have very little experience with diesels. Truck will start just fine when cold, at operating temp cranks and cranks, wont even try to fire. the following parts have been replaced. Drivers bank injector O'rings, high pressure oil pump, injector pressure regulator, fuel pump and O'rings on fuel return lines at cylinder heads. When engine is warmed up and wont start, give a little shot of starting fluid and it will start right up. Any help would be greatly appreciated.

[steven kiser]

There is an issue with these and the crank shaft sensors. Usually there are more than one issue with this fail but i've seen it solved by replacing the sensor. take it out and see if it looks like it's been hitting the toner ring. If yes then there is a shim kit available through a tsb. Remember you're dealing with a dsl and the only way to control it's starting and stopping is fuel. There are also issues with the wiring harness where it attaches to the valve cover gasket. Look closely at the plug.

I've seen issues with the fuel lines from the tank to the injector pump being porous and sucking air but again there are usually more issues associated with this.