I have had this truck for a couple of years now, and it seem that ever winter I have some trouble starting it when its cold. Its happened too many time to just be a coincidence. It has a new battery, alternator, starter, and all three work perfectly. The truck will turn over just fine and it sounds strong, and sometimes it will actually fire but its as if its only running on a few cylinders and it sounds horrible. Then suddenly after about three or four turns of the key it will fire up and run fine. Once its actually running it has no problems. I’m not sure if its something with the ignition system or the distributor? But it only seems to happen when its cold. Can anyone point me in the right direction so I can get this diagnosed and fixed?
First lets commend you on the proper use of the term “turn over” …THANK YOU… LOL Sort of an inside joke around here … Nevermind…
IN FACT I even defined this and asked the document to be made a “sticky” so that everyone could read and know the terms…Turn over is what your STARTER MOTOR does for you…so when you turn the key…and the starter is working… It will TURN OVER your engine…until it STARTS… and then RUNS.
So…You say she turns over Strongly…which is good…this tells us many things including the fact that your starter motor and batt are in good solid shape
When you say it runs but sounds as though its missing…this very well be the case… Another clue is that it takes 3 or 4 cycles of the key to get her running smoothly on all cylinders…this points to a fueling issue. Because everytime you cycle the key…you should hear your fuel pump…and in this vehicle as with most Fords… YOu will hear a sort of HISS sound to indicate the pump is working.
It sounds to me like you need to build up proper fuel pressure…and the cycling of the key is what is doing this for you. A leaky fuel injector can be the cause of this…what happens is that one injector is stuck open lets say…and all the fuel pressure that is normally primed up and waiting there for you…was spent leaking out of the tiny orifice of the end of one of the injectors… This does several things… ONE it will flood the affected cylinder out with a LOT of fuel… TWO it drains your fuel rail of pressure and subsequently FUEL.
So what you are sort of experiencing is a vehicle that is just getting running after being run out of fuel and then refilled wih gas again.
When a vehicle runs out of fuel…it needs to properly prime the fuel rail so all injectors can spray fuel when the ECU tells it that it is time with a ground pulse. Your cycling of your key is where all these clues came from…the pump is building pressure and fuel volume up upon those key cycles…and after 3 or 4 cycles it has caught up and can then give any and all injectors the fuel they need.
ANOTHER SUSPECT I BELIEVE would be your FPR…or fuel pressure regulator…this may be hung up in some way and is letting fuel bleed back into the tank.
I would start with GOOD quality Fuel injector cleaner…can be found everywhere…buy one thats 20 or so and use it at a high concentration of fuel…lets say w a 1/4 or 1/2 tank per bottle…see what you get. ALSO DONT OVERLOOK THE FUEL FILTER…it may be clogged and flowing slowly!!!
Next you can inspect or replace the FPR bec its easy…take it off and tap it or try to see if it is hung open in any way letting fuel escape into the tank…
The 3rd and more complex thing to try is to individually ground out each neg side of each fuel injector… Find the neg side of the injector wiring…and ground it out… THIS will hold each injector open fully and may allow any piece of debris to PASS out of the injector…
Start w fuel injector cleaner…and maybe a new fuel filter first… THESE ARE EASY TO DO…
Then you can move into more complex diagnostics later…
Hope this helps…you have homework to do now
Blackbird, Thanks for this advice. This makes a lot of sense. Recently I was having trouble with my check engine light coming on, and I noticed that I was smelling fuel when I would get out after driving a short distance. I changed my fuel cap, as this is the easiest of fixes. This still didn’t fix my problem. After a little poking around I noticed that the filler neck was rusted all to hell. I replaced that AND my fuel filter for good measure. That has fixed my check engine light problem. As for the starting problem I have considered the injectors but I haven’t done work on the injectors before. I don’t really know what kind of access I would have to get to them. I will try the injector cleaner and do some research on the injectors, and regulator. Thank you.
Assuming all the owner manual recommendations for routine engine service items and intervals are up to date. Well, it has to be from among air/fuel mixture, spark, or timing. I think the more likely is the air/fuel mixture. A good comment to check the fuel rail pressure above to rule out the fuel pressure regulator. If you are unsure of a good spark, there are inexpensive gadgets available which make testing for spark easy at most auto parts stores. Checking timing during cranking would be better to give to a well equipped shop.
The engine has to have a much richer mixture on a cold start, and the colder, then even richer is needed. Otherwise it won’t start in cold weather. On your truck, either you have an additional injector called a “cold start” injector which pumps in extra gas on cold starts, or, more likely, the ECM fires in extra gas through the existing injectors on cold starts. There is likely something wrong with this process happening on your truck. Not enough extra gas is being injected.
The way it knows it is a cold start is by the engine coolant temp sensor. So that’s one thing to check. This is often not the same gadget that is used to display the engine temperture on the dashboard. So your dashboard reading might be ok, but the other, not. Often the cold start process is vacuuum controlled too, so if you have a vacuum leak, or a vacuum device that is failing, that’s a possibility.
Anything causing a leaner than desireable mixture could contribute too. Like vacuum leaks, or an air leak in the intake manifold, allowing unmetered air past the MAF.
And it’s possible the mixture is too rich, rather than too lean. Unlikely, but possible. One way to disprove this is to smell the exhaust area when it doesn’t start. Does it have a gasoline smell? If so, it may be that too much rather than too little gas in the problem.
I recently took this to my mechanic, he told me that it might be a sensor. Whether or not it was the coolant temp sensor I can’t be sure. It plugged into the hose that flows from the air box to the throttle body. It was just a small sensor that pulled right out. I bought a new one and when I changed it I noticed that the clip that was on the wiring harness was broken, and thought that maybe it wasn’t getting a good connection. I couldn’t buy a new clip because that would mean potentially buying a whole new wiring harness just to fix one clip. SO, with a healthy dose of electrical tape that problem was fixed. ALL of the wiring on this truck seam to be in good condition, no fraying, corrosion of any sort. I can say on many occasions that I have smelled fuel, but its usually after a short trip after the truck has been running smoothly. The spark plugs were changed shortly after purchasing the truck, and one of them failed after carbon was built up on it. I changed the plug and took the truck to have it “decarbonized” at the dealership. The mechanic said that it filled the ENTIRE shop with black smoke and it ran like a dream after this. I’m sure the excessive carbon build up might have something to do with an improper fuel/air mixture. I’m just not sure whats causing this. This is really my first vehicle purchase, and I’m really enjoying the adventures of fixing these problems on my own, even if it seems they are getting a bit excessive.
I think the sensor you mention above is the intake air temperture sensor. That could contribute to an improper fuel/air mixture during normal running. You should definitely veryfy it is fixed for that reason alone. The ECM must know the correct intake air temp to adjust the mixture correctly. If the sensor was completely broken though, I think you’d see a check engine light. Whether it could be a cause of cold start performance? I don’t know.
Yes, the wrong fuel/air mixture during normal running could cause carbon deposits in the engine. It could cause overheating also. Do you notice any overheating problems?
The engine coolant sensor usually screws into the engine somewhere near a cooling pipe. For it to work, it must be immersed in the coolant.
I have not noticed and over heating, the gauge seems to stay in the middle consistently. Although the other day I did notice that my antifreeze reservoir was extremely low. It doesn’t seem to have any effect on the truck as of yet.
The BIG clue here guys is the 3 to 4 key cycles…this is making the pump prime 3 to 4 x…and then she runs on all cylinders…before that he has a miss or choppy running engine… Just like after you run out of fuel and refill the tank. It takes several cycles of the key/fuel pump to fully prime the rail and supply all injectors with fuel.
Its either an injector sticking open…the FPR…or even a slow flowing filter…but I think its one of the former.
EASY test is to go under the hood before a cold start and push in the schrader valve on the fuel rail to see if it sprays fuel out…IF NOT… Its the tests I outlined prior… a stuck injector…or the FPR bleeding back to the tank…
This is an important test…DEFINITELY DO THIS on the next start… Tell us if you have fuel spraying out of the rail…
THEN…cycle the key several x…see what the pressure is like then… HELL If you had a Fuel pressure gauge you can leave it on the rail…and watch it… Bet it drops over time…it SHOULDNT…but in your instance I bet it does
@BriGuy, you may want to crawl under the truck and make sure the water pump isn’t starting to leak. If it looks crusty around the weep hole, it’s time for a new one.
So finally the other morning I walked out to go to work, fully expecting my truck not to start on the first turn of the key. What I did not expect was for it not to start at all. I had to tow it to a mechanic who told me it was a bad fuel pump. Now although I can see how this makes sense, I can’t understand how my truck would run perfectly with regular fuel pressure until it got cold outside. The cold would make me think that an O ring on an injector was shrinking and making it lose pressure. The only reason I’m hesitant about letting him repair this pump is because its going to be close to 700$ for parts and labor. Does anyone have any thoughts? suggestions?
Your fuel pump has been giving you warning signs.
I expect that the mechanic properly diagnosed it, right?
Leaking injectors are not typically the cause for no start/hard start.
Fuel pumps and regulators are.
Your truck is 12 years old. I just replaced a fuel pump on a 2003 GMC Sonoma. The fuel pump check valve quit. Wouldn’t hold pressure after shutting off, very long cranking time before starting.
Some fuel pumps don’t even last as long as yours did.
It had a good run and now it’s time for another one.
I figured as much, I wish this was something I could do myself, as I like to take things apart and put them back together. BUT, the day before it died I had filled the tank. and I don’t have the tools to drop an empty tank, let alone a full one.
Does the engine rev itself to 2,000+ rpm when it starts cold? If not, the throttle and IAC might be significantly plugged with sludge or the IAC pintle may be sticking.
I got a new throttle body and IAC when I replaced my upper intake manifold, both where very well cleaned and brushed before reassembled.