won't start
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won't start
my 94 F150 with a 300 in it won't start, it cranks over allright but will not start. I put starting fluid in the intake and it starts for a second or two but won't stay running. I checked all fuses and relays, they are good. the filters are alright, and I checked the fuel pumps they come on like they are supposed to. anyone have any sugestions on what else I can do?? I am no mechanic but can do most things. please help!!!
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There is no advantage to double-posting on the same BBS.
https://www.f150forum.com/f10/no-start-452776/
https://www.f150forum.com/f10/no-start-452776/
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some possible causes based on what i have dealt with
my 94 F150 with a 300 in it won't start, it cranks over allright but will not start. I put starting fluid in the intake and it starts for a second or two but won't stay running. I checked all fuses and relays, they are good. the filters are alright, and I checked the fuel pumps they come on like they are supposed to. anyone have any sugestions on what else I can do?? I am no mechanic but can do most things. please help!!!
1. a faulty idle air control valve which is best replaced not by a new aftermarket idle air control valve but with one from another 4.9 in a junkyard (might want to blast it with carb cleaner too). some background on why i feel this way about aftermarket iac valves: the original idle air control valve that was on my truck started malfunctioning. i replaced it with a hitachi iac valve from rockauto. it didnt function right. truck would idle up and down and would stall. i take it to a mechanic thinking its a vacuum leak. they assume its the coolant temp sensor and replace that. truck still stalls. they replace the hitachi iac valve with a standard motor products iac valve. so, i experiment, go to a junkyard in mesquite, and get an idle air control valve off of a derilect truck. problem solved.
so maybe you have a faulty iac valve.
2. oil may possibly be getting in your spark plug wells. maybe its time to go up in viscosity of your oil (significantly if need be, some people run as heavy as 15w40 in their 4.9s). maybe its time to get that head gasket, valve cover gasket, or both changed. maybe you shouldnt be running synthetic oil in something that has always ran conventional oil. why? because it will leak like crazy. im not saying you have done this, but i have done this and it caused me a week long nightmare of multiple oil changes and spark plug changes because i didnt want to bother getting the head gasket or valve cover gasket changed on an engine with this high of mileage and this old. this is my daily driver. its my only driver. and i cant keep throwing money into it as it would take away from me saving for paying cash for a new econobox. hopefully this doesnt bite me in the you-know-what down the road.
3. a battery which is at the end of its life. 4.9liters are big engines. they require lots of cranking amps. maybe you can get a lot longer life out of batteries than i can, but for me iive noticed that the battery life in my particular 4.9 liter is between 2 and 2 1/2 years. the previous owner of my truck complained of the same thing, and he was running interstate batteries. which are supposed to last longer.
4. a fuel filter which may desperately need changing: to make a long story short, a clogged fuel filter can cause a no start. although again its more than likely that a stall would bring this to your attention first before a no start.
5. solenoid: although with this one you wouldnt just get a no start you would get a no crank.
Last edited by Charles Chairez; Aug 18, 2019 at 12:49 PM. Reason: i reread it and didnt like the way i presented the answer so i changed some things
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Can't say I agree with Charles completely.It is vital to know the difference between cranking and starting in getting a problem resolved.
1. IAC won't keep an engine from a total no start issue.
2. Give me a break.
3. If his engine cranks ok, his battery is fine.It takes more energy to crank an engine than everything else combined.I have averaged five years from my batteries in my (4.9) since I bought the truck new in 87.
4. Yes, a fuel filter being plugged up can cause a no start issue and would be on my list to check.
5. Nope, if his engine cranks, the starter solenoid is doing its job, he's cranking ok, so why mention it..
He can get activity by using ether so that tells me he likely doesn't have enough fuel pressure to start his engine. Just because he can hear the pump run doesn't mean it is totally doing its job. Specs call for 45-60 PSI of fuel pressure for a 94..
1. IAC won't keep an engine from a total no start issue.
2. Give me a break.
3. If his engine cranks ok, his battery is fine.It takes more energy to crank an engine than everything else combined.I have averaged five years from my batteries in my (4.9) since I bought the truck new in 87.
4. Yes, a fuel filter being plugged up can cause a no start issue and would be on my list to check.
5. Nope, if his engine cranks, the starter solenoid is doing its job, he's cranking ok, so why mention it..
He can get activity by using ether so that tells me he likely doesn't have enough fuel pressure to start his engine. Just because he can hear the pump run doesn't mean it is totally doing its job. Specs call for 45-60 PSI of fuel pressure for a 94..
Last edited by raski; Aug 16, 2019 at 06:12 AM.
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I too am now having no start issues
ok so based on my experience and the number of no starts and stalls i've had with this particular make (my 4.9 is a 1994 just like yours) im going to list 6 or 8 causes of why yours might be stalled.
1. a faulty idle air control valve which is best replaced not by a new aftermarket idle air control valve but with one from another 4.9 in a junkyard (might want to blast it with carb cleaner too). some background on why i feel this way about aftermarket iac valves: the original idle air control valve that was on my truck started malfunctioning. i replaced it with a hitachi iac valve from rockauto. it didnt function right. truck would idle up and down and would stall. i take it to a mechanic thinking its a vacuum leak. they assume its the coolant temp sensor and replace that. truck still stalls. they replace the hitachi iac valve with a standard motor products iac valve. so, i experiment, go to a junkyard in mesquite, and get an idle air control valve off of a derilect truck. problem solved.
so maybe you have a faulty iac valve.
2. oil may possibly be getting in your spark plug wells. maybe its time to go up in viscosity of your oil (significantly if need be, some people run as heavy as 15w40 in their 4.9s). maybe its time to get that head gasket, valve cover gasket, or both changed. maybe you shouldnt be running synthetic oil in something that has always ran conventional oil. why? because it will leak like crazy. im not saying you have done this, but i have done this and it caused me a week long nightmare of multiple oil changes and spark plug changes because i didnt want to bother getting the head gasket or valve cover gasket changed on an engine with this high of mileage and this old. this is my daily driver. its my only driver. and i cant keep throwing money into it as it would take away from me saving for paying cash for a new econobox. hopefully this doesnt bite me in the you-know-what down the road.
3. a battery which is at the end of its life. 4.9liters are big engines. they require lots of cranking amps. maybe you can get a lot longer life out of batteries than i can, but for me iive noticed that the battery life in my particular 4.9 liter is between 2 and 2 1/2 years. the previous owner of my truck complained of the same thing, and he was running interstate batteries. which are supposed to last longer.
4. a fuel filter which may desperately need changing: to make a long story short, a clogged fuel filter can cause a no start. although again its more than likely that a stall would bring this to your attention first before a no start.
5. solenoid: although with this one you wouldnt just get a no start you would get a no crank.
1. a faulty idle air control valve which is best replaced not by a new aftermarket idle air control valve but with one from another 4.9 in a junkyard (might want to blast it with carb cleaner too). some background on why i feel this way about aftermarket iac valves: the original idle air control valve that was on my truck started malfunctioning. i replaced it with a hitachi iac valve from rockauto. it didnt function right. truck would idle up and down and would stall. i take it to a mechanic thinking its a vacuum leak. they assume its the coolant temp sensor and replace that. truck still stalls. they replace the hitachi iac valve with a standard motor products iac valve. so, i experiment, go to a junkyard in mesquite, and get an idle air control valve off of a derilect truck. problem solved.
so maybe you have a faulty iac valve.
2. oil may possibly be getting in your spark plug wells. maybe its time to go up in viscosity of your oil (significantly if need be, some people run as heavy as 15w40 in their 4.9s). maybe its time to get that head gasket, valve cover gasket, or both changed. maybe you shouldnt be running synthetic oil in something that has always ran conventional oil. why? because it will leak like crazy. im not saying you have done this, but i have done this and it caused me a week long nightmare of multiple oil changes and spark plug changes because i didnt want to bother getting the head gasket or valve cover gasket changed on an engine with this high of mileage and this old. this is my daily driver. its my only driver. and i cant keep throwing money into it as it would take away from me saving for paying cash for a new econobox. hopefully this doesnt bite me in the you-know-what down the road.
3. a battery which is at the end of its life. 4.9liters are big engines. they require lots of cranking amps. maybe you can get a lot longer life out of batteries than i can, but for me iive noticed that the battery life in my particular 4.9 liter is between 2 and 2 1/2 years. the previous owner of my truck complained of the same thing, and he was running interstate batteries. which are supposed to last longer.
4. a fuel filter which may desperately need changing: to make a long story short, a clogged fuel filter can cause a no start. although again its more than likely that a stall would bring this to your attention first before a no start.
5. solenoid: although with this one you wouldnt just get a no start you would get a no crank.
Update
Great news everyone! I too am once again having problems with getting my truck started. That means we are in this together man! lol
6. Engine Control Module (ECM): a faulty engine control module could cause a crank but no start. If you are comfortable with it, you should pull it out, open it up and check to see if it has any burnt capacitors or fuses on it. . If it does have a burnt capacitor or fuse you could either solder in a new fuse/capacitor yourself, or have an electronics repairman solder in the new fuse or capacitor for you. I personally am going to check that first before I start just throwing parts at my truck again. Be sure to remove the positive terminal before messing with any of that.
my source for this possible diagnosis:
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