Barry St John

Just finished a 1600 mile round trip to Washington and had a few problems pop up. Most important cel came on at about 1000 miles with no codes but I had been watching the fuel pressure and I hope it's related. Pressure had been fluctuating between 11 and 13 psi at idle and 9 to 11 at cruise. usually it's normal but it will run at the lower pressures for a hour or so and then heal itself? Also noticed that the bump when the key is turned on is low - only a couple of pounds and a couple of times it didn't bump at all. Lowest pressure I've seen pulling hard is 7 lbs. That is typical for this pump since it was warrantied by the dealer 10 k mi ago. Here is the really wierd part. My right radio speaker picks up a cyclic pulse or hum when it is acting up!! The electrical connections look good and they seem to be tight in the lift pump circuit as far as I can trace it. I'm going to take in into the dealer monday to have them read the codes and see if they can find anything but I'm afraid it's going to be that everything checks out. I'll keep you posted about findings but am wondering if anyone else has had simular problems. Also I had a problem with shifting for 2 hi to 4 hi while moving. If I stopped it shifted in ok and works ok with no noise but it would grind if I tried to shift while in motion. After a day of this it cured itself and now is working normally? Ujoints and axle function are good with no new noises!! Sorry about the long post. Thanks for any thoughts in advance!!

Geico266

LP is weak and getting weaker. Fluctuations are the sign of continued problems. They don't heal themselves, sorry.

Are you on pavement when you are trying to shift the 4 wheel drive?

Barry St John

That is about what I figured but I'm wondering about the circuit that supplies the power to the pump. This pump has been a little weak and quirky since the day it's been installed and I wonder if I have more of a problem that just the pump. Maybe I'll hook up a jumper with 12v to the pump from the batt with it isolated from the circuit and see what the pressure is. As for shifting into 4wd it was on ice and snow. Tried it with a little throttle, no throttle and with the clutch in - no dice - I don't have a clue what could cause that unless it was the 16 hr drive and I was trying to put it in reverse!! Thanks for the reply. Barry

MadDog01

Barry, sell it and buy a Ford!!!!!!! You'll have plenty of time to wrench, now that you are retired!!

Gary

Geico266

Some are bad right out of the box. Just replace the pump. The fluctuations are sign of impending failure.

Barry St John

Thanks for the info Geico266. I agree and will get another lift pump from cummins. It also seems that I'm not getting the signal from the pcm. I changed the filter today and could not get the pump to start when the ignition switch is turned on. I filled the filter canister and got it to start with a little cranking. Found a thread where Haulin in Dixie mentions not getting the signal from the pcm. I jumpered out the lift pump from the batt and get a solid 13-14 psi at idle and 11-12 psi at cruise. Still don't trust the pump but I think I also might need a new pcm! I'll keep you posted.

Barry St John

FYI Dealer replaced lift pump even though it met flow test specs. We checked signal from ecm at switch on and found voltage to be ok at pump. The dealer did see reduced pressure at times during the test and felt the pump was bad so he replaced the pump. It's too bad that not all dealers are this reasonable!!! The mechanic felt that problems with ecm signal to pump are unusual but that it can occur. All in all I'm very happy with the service dept at this dealer. Thanks again Geico266 for your reply.
Bear