Hi all, new user with a question about a fuel pump problem I'm having... Occasionally the pump will not come on with the key as I prepare to start car. The motor will turn over but not start. This has happened many times and I have dropped the tank a couple of time to check the pump and by so doing it the pump will work fine for months when I put it all back together but I'm not sure I'm on the right track. As I sit here this morning drinking my first cup of coffee and waiting for the gas tank to drain (I curse the engineer who thought saving the 50 cents by NOT putting in a drain plug was a good idea) and having to put a small plastic tube down the vent tub to drain the tank. Anyway, I'm thinking there must be a pressure switch somewhere to tell the pump to turn on or off. So before I dump a couple hundred dollars into a new pump anyone know where the pressure switch is located, what kind of voltage should I see and or have any suggestions as to where to go next. thanks Walt
Bought new pump ($175) and tried it by attaching to truck fuel pump connectors and turning on the key but got nothing. Put old pump back on the connector and it worked? So put the new one on again and this time it worked. So now I'm thinking it's got to be something else that is wrong. Connector seems clean and seems to make good contact. I've been told that there are other parts to the circuit that come into play on start-up and for running the truck. The PCM relay will energizes the pump for a second or two when the key is turned to ignition and they again when some other component shows the engine turning to provide fuel to the running truck. If it was the PCM relay I would think I would also have trouble when driving the truck with it stalling?? Just happens at start up when I turn on the ignition and don't hear the pump prime the fuel lines.
So any thoughts, suggestions, or direction of what to do next would be greatly appreciated before I waste another 175 bucks on something I really didn't need to replace.
I did stumble across this schematic (see attachment) but I'm sill not sure where most of this stuff is located. Think the PCM is on the passengers side but what, where is the other stuff like the fuel module or EEG .
The PCM is on the passenger side, right above the kick panel, and right behind that kick panel if the fuel pump reset switch.. Next time it doesnt start, try to see if that switch was tripped. I wanna say it gets tripped off inertia (like in a crash), but just a thought!. Not sure if that helps you any, but thats where those two are located! Hope that helps!
My truck has the exact same problem. It only seems to not work in cold weather though. Doesn't matter if the engine is cold or warm, I've had this issue after I've just turned the truck off and tried to restart.
Let me know what you find out. I haven't bought a new fuel pump yet because I think it may be something else. You have to cycle the key multiple times until you hear the fuel pump prime before trying to start. I didn't have this issue at all during the spring or summer and it has started back up again with this cold weather
I am having the same issue with my 2001 S-Crew. I am hoping to replace the fuel pump over the long holiday weekend so I will let you know if that solves it... but if you are able to solve it please reply.
Thanks all, Wet rainy weather here in the northeast so I'm not about to crawl around the truck till it gets a litter nicer outside. Give me a chance to get more info before I go crazy trying to find the problem.
Best I can tell now is it is the PCM module or the relay. Strange that the truck only has a problem on startup and not while driving even though the same circuit controls both. Only thing I can think of is that it is a ground problem. Could the PCM get it's ground from two points? One from the module when it it activated by the key and later when it'c circuit is completed by the run ignition.
I might have to bite the bullet and go (shudder) to a Ford dealer and have them look at it.
P.S. if anyone reading this has any additional thoughts please don't hesitate to put in your two cents.
Didn't get a chance to replace the fuel pump over the weekend. I ordered a fuel pump off Rock Auto so I am waiting for that to come in. I am also going to replace the fuel filter. On my truck when I do get it to run you can hear the fuel pump buzzing really loud like it is either going out or working really hard to pump fuel. Normally when the truck was running you could not hear it. Right now I have just over a half tank so it is not because it is low on fuel.
Hi All, been cleaning contacts and testing wires, relays anything I can find that might be causing the problem. I returned the new fuel pump cause the old one is working just fine. Every time I turn the key to the ignition on position I can hear the pump working for the second or two need to prime the system. I can start truck and let it run without any issues. Just hate to not have a clear idea what I did or what might still be wrong. Don't want to drop the gas tank to many more times if it does act up and stops working again. Each time I drop the tank the pump seems to fix itself. And yes I have checked that connection at the pump a couple times and can't see that it is the cause of the problems.
Anyway, I'll keep ya' posted if anything changes one way or another.
Just wondering if you had any updates? Did you solve the mysterious fuel pump issue? I am encounter a similar issue with my truck right now.
Mine is a 1999 F150 4.6L, 4x4, and yes, mine is in the Northeast too. Yesterday I parked my truck and hopped in my coworkers truck for work in the morning. The truck started fine as usual, but when I returned, she would crank, but no start. I ended up finding two blown fuses, and replaced them to no avail. Figured it might be the fuel pump or relay. Checked for gas, and it was getting plenty... When the key is turned the fuel pump starts, but doesn't seem to run as long as it should. Maybe pumps for a second, but not enough to fire her up. The spark plugs and wires were replaced about one year ago, so it's doubtful that is the issue. I replaced the fuel pump, and same thing. Turns on for a second and shuts off again. We bypassed on the fuel pump relay, and let the fuel pump run a few seconds, still no start...
I have some questions about this PCM and fuel pump reset that you and others have mentioned. But first the relay... Is it possible that there is a second relay somewhere along the line? I know on Chevrolets (shudder), the timer is built into the fuel pump relay, but on my Ford, I don't think it is... Might this PCM module be the answer to my problems? If it was some sort of fuel pump reset, then how would it run even for the one second it does?
It's not the fuel pump, relay on the box, fuses, plugs, plug wires, filter, or any other things I can think of. Doubtful it's the regulator... I don't think a regulator has ever malfunctioned on any vehicle ever (as far as I know)...
Just basically wondering if you solved your issue, so maybe your issues could solve mine?
Other comments are very much welcome too...
And hurry up before I junk it and buy a Chevy. Hahaha... (Completely kidding right there)... Shudder shudder... Help!!!!
I spoke with my father about your problem, too... Not sure where you are at with it, but he thinks yours might be related to a "cooling sensor" of some sort. Almost like its registering not as cold outside as it actually is, so in response, it's not sending the extra fuel it needs to start in colder weather. He thinks yours is simply running to lean... does it run fine after the engine warms up? Not sure if this helps, but that was his thoughts. I figure any suggestions help!
Walt, it sounds like your relay is failing. It's a continuous on relay so it either works or it doesn't. It's rare for the relay to fail in the middle of functioning. If you don't want to just replace it, just use two paper clips to substitute the relay when it won't start. I will look at the diagram and tell you the pin numbers
Ehh, it doesn't say but it's a 4 leg relay so two legs will be hot with the key on and two will not. just jump the two hots to the two nots and the pump should run. Keep in mind the pump will only get power from the second leg for about 5 seconds in the accessory key position.
We thought the same thing about mine (similar issue)... But it wasn't. All the relays are the same, so we switched them... Nothing. Then rigged up a fancy homemade tester to jump legs. That's not it either... Think the relay is fine on mine. (Please see earlier posts)... Do those fuel rails have screens in them? Or something that could clog easily?
I have a 1999 f150 and I am experiencing a similar problem except my truck starts when cold but once it warms up or recently when it sat in the sun, it won't start. It has been happening on an doff for a couple of years but only in the summer. it works fine during the colder months. I usually just keep it running when it is warm out except today, I left it running then it stalled out and it won't start at all. Was originally looking at a crankshaft sensor. Has anyone experienced this problem?
I would back probe the fuel pump wiring when it won't run the pump. You may be getting power but no ground. There is also a connector by the air box which the fuel pump wiring goes through may want to check that connector too. Look for the bigger wires that feed the pump. Yellow or pink can't remember. Had a F150 at work kept popping the pump fuse. Found customers CAI filter rubbing on the wires. Filter was metal so direct short to ground. He was on his fifth pump. I would try a relay first. If still a problem, back probe the relay and see if the PCM is giving you a good ground at the relay. The relay should have 1 constant power. 1 keyed power. 1 ground from the PCM and the load.