I have a 2002 ford 350 diesel that has a lot of miles. the way it runs , I suspect the electric fuel pump. when I first turn on the key to start it . I hear the pump start running for about 30 to 40 seconds before it shuts off . is that too long for the pressure to build up. just bought the truck about 2 months ago. I`m new to diesel. but have heard the 7.3 can run forever.

 

The fuel pump is controlled by the PCM. When you first turn on the key, the PCM closes a relay which provides power to the pump. If the engine is not started within 20 seconds, then the PCM will turn the pump off. As long as the engine is running, the fuel pump is pumping. It generates about 100 psi of pressure to the fuel bowl/water separator. There is a pressure regulator at the bowl that opens around 55 psi which allows fuel to flow back to the tank via a separate return line.

So, even with the pump running, the max pressure the system can build is 55 psi (plus or minus) unless you change the spring inside the FPR.

If you are hearing a pump run for 40 seconds...that might be the vacuum pump over on the right side of the engine bay. Is that possible?

 

no it`s not . I crawled under the driver side an it`s got to be the fuel pump. is the fuel pump supposed to have a check valve in it ? I can turn on the key but not start it an let the fuel pump run until it shuts off , then turn the switch back on an it runs for another 30 to 40 seconds. Another thing is , I can be driving it away from a stop an if I`m taking off fast , the motor quiets an goes back to idle an stays running , take your foot of the pedal an mash it back down an it runs perfect............any ideas????

 

it was the vacuum pump running, I took it to ford dealer an they put it on a machine an said it was the injection control modual.. they want 1200 dollars to change it...I looked it up on the e-bay ,,,I can get one for about 360.00 dollars..how hard is it to install myself....it just looks like you unplug it an plug in the new one......could that be the problem??????

 

They IDM is located inside the fender....takes 20-30 minutes to change.
Did you happen to get a printout of the codes they found? The IDM doesn't fail that often. Can you describe the symptoms in more detail? There are many more likely causes for IDM codes that should be explored first.

 

ford dealer said ......there was 2 codes that said a sensor(2) was giving a bad reading . he didn`t say what they were . but he did say the IDM would take care of the problem...... the problem is every once an a while , maybe once or twice a week after stopping an taking off , usually under brisk acceleration, not full power, around 30 or 40 miles an hour the motor shuts off to an idle , I take my foot off the gas pedal an push back down an it takes off back to running good. may not do it again for days. could it be one off the sensors causing this to happen???

 

The IDM usually works or it doesn't...they normally don't have intermittent issues. The Ford dealer should know better....the Injector Driver Module will never correct a bad sensor reading. If the IDM looses sync with the PCM the engine shuts off. If the IPR coil has an intermittent failure, the engine shuts off. Both conditions are just like you turned the engine off with the key. No stumbling, no fixing itself...the engine just shuts off.

Your symptom sounds like a bad TPS or possibly even a chaffed shifter wire. Sometimes the OD switch harness shorts out and blows a fuse that kills your instrument cluster and throttle position sensor. When that happens the engine will only idle. I've heard of one or maybe two instances where the fuse did not blow yet it still caused the symptoms you describe. I'd start by checking the OD wire first. It's free and easy to do. If that checks out then I'd look at the throttle position switch. Sometimes spraying it down with some electrical parts cleaner will clean up the micro-switches and it might function again for a while.

You really need to know what the codes were. Without those we are simply taking guesses as to what the issue might be.

Here is a link to the OD wire fix. This write up is for '02 and up. https://sites.google.com/site/woodnt...nance-articles

Scroll down to the bottom of the page and download the file that is labeled "TransmissionShifterLeverChafeRepair...pdf"

 

thanks.... all that info. is very interesting an thank you for the link to more things that I should know about this truck... this truck has 484,ooo miles , it was used to transport travel trailers all over the U.S. an I knew the driver who owned it ..he died shortly after I bought it from his wife

 

shake N bake I checked for a frayed wire in the steering colume but nothing wrong,,so I went over the paper work from FORD dealer an saw it did have the 2 sensors that were bad on there. it says conn. and evp sensors need replacing,,, what does that stand for? an could that cause the motor to shut down to an idle when I`m driving some times. any help would be appreciated.......thanks