5.4L Getting Hard to Start
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Senior User
Joined: Oct 2018
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From: Georgia
5.4L Getting Hard to Start
Hello all,
A couple weeks ago, I went on vacation for a week. I took a different vehicle and my ‘99 F-250 was left sitting outside for the time. When I got back, the truck took forever to start. After it finally did start, it ran VERY rough for maybe 15 seconds, whole truck was shaking pretty good, then ran normal. Ever since, my truck has been increasingly harder to start. It’s always fired right up nearly instantly until now. I’m about to spend 4 grand on body work for it so this makes me a little nervous that I’m about to have to cough up even more money. It’s really only hard to start after it’s sat overnight, or after I’ve driven somewhere and it’s sat for a little while. If I get it running, shut it off and then try to start again, it starts great. It still runs great. Plenty of power, no DTC, fresh fuel, clean air filter. I know there’s tons of other threads on this but I really can’t find a straight answer. Don’t know what to do!
Thanks in advance!
A couple weeks ago, I went on vacation for a week. I took a different vehicle and my ‘99 F-250 was left sitting outside for the time. When I got back, the truck took forever to start. After it finally did start, it ran VERY rough for maybe 15 seconds, whole truck was shaking pretty good, then ran normal. Ever since, my truck has been increasingly harder to start. It’s always fired right up nearly instantly until now. I’m about to spend 4 grand on body work for it so this makes me a little nervous that I’m about to have to cough up even more money. It’s really only hard to start after it’s sat overnight, or after I’ve driven somewhere and it’s sat for a little while. If I get it running, shut it off and then try to start again, it starts great. It still runs great. Plenty of power, no DTC, fresh fuel, clean air filter. I know there’s tons of other threads on this but I really can’t find a straight answer. Don’t know what to do!
Thanks in advance!
Hotshot
Joined: Jul 2005
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the fuel pump puts out maybe 40 psi... when you shut it off, the fuel PRESSURE is maintained in the line at the injectors so that when you start cranking, you have fuel immediately. There is a fuel pressure diaphragm that lets excess pressure run back to the tank.. I think it is on the fuel rail, on the drivers side rear. If it is LEAKING, then the pressure will run back to the tank after setting... you have a Schrader valve on the fuel rail that you can check pressure.... another test is to turn the key on for 3 seconds and let the pump run to build up pressure, then shut it off for a second and turn back on for 3 seconds... do that 3 times to PRESSURE the fuel rail, then crank and see if it starts up quick... If so, you have narrowed down the problem to loss of fuel..... I think there is a check valve in the fuel line a the tank fuel pump also... that's another potential pressure leak point.
if you have pressure and the truck still does not start when COLD, then you might have a sensor problem / ambient temp ..... similar to what the CHOKE did in the old days for COLD START.
if you have pressure and the truck still does not start when COLD, then you might have a sensor problem / ambient temp ..... similar to what the CHOKE did in the old days for COLD START.
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From: Georgia
Well I got impatient. It’s been sitting a while so I figured I could go ahead and try it. Cycled the key 3 times, gave the pump plenty of time to pump up, and it still took a good 5 seconds of cranking for it to start up. I’ve also been noticing that when I start it cold it runs in high idle for a few seconds. I’m in Georgia, and it’s certainly not cold here and I haven’t seen it high idle since winter. So I’m thinking it actually may be a sensor. But which ones would be reliant on starting and idle?
Fleet Owner
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From: 0,0,1
The Coolant Temperature Sensor (CTS) is one of the main sensors that affects start up by adjusting the air/fuel mixture based on the engine temperature. But the best thing you can do is connect a scan tool that will read the data and tell you which sensors are reading what.
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From: Georgia
I have a tuner in the truck which shows this data and reads DTCs. My coolant temp sensor works fine as far as I can tell. Always seems accurate and goes up to around 200 when the truck warms up
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Senior User
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From: Georgia
Is there any chance of this being a head gasket issue? Given the age of the truck and that it’s creeping up on 189k, I wouldn’t be surprised. Would it be possible that coolant is leaking into cylinder(s) while it sits, creating a hard start?
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IMHO...plugs #1, COPS if they were non-oem units #2 and aside from the fuel system which has been presented, It could very well be the fuel blend is not right for the weather you are experiencing...….unlikely head gasket.
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From: Georgia
I would think the same thing, but at the same time the truck runs perfectly after it’s started, it’s just taking far longer than usual to actually start. So wouldn’t it be performing poorly on the road if coils/plugs were bad?
Lead Driver
Joined: Sep 2006
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If you expect to solve the issue, you have to stop the causal refrains the plugs are good, the temperature comes up fine etc. and look at each part of the system that starting depends on.
One fault and you have a starting issue. Unless you check it all out it's just guessing. That's why you ended up here.
Cold starts:
1. Key to on before cranking causes the fuel pump to run a couple seconds.
2. The PCM looks at the cylinder head temperature and the intake air sensor to set fuel richer, set ignition timing advanced and open the intake air controller.
3. Cranking restarts the fuel pump from the crank sensor signal.
If you don't check each of these functions then you have no idea what's going on.
Could be low fuel pressure from a faulty fuel pump, faulty regulator, intermittent crank sensor. Fuel regulator leaking gas back into the intake causing flooding.
Could be the IAC stuck closed from the last time the motor was run=no idle air.
Faulty CHT, IAT etc.
It's not plugs or coils if it runs otherwise..
Good luck.
One fault and you have a starting issue. Unless you check it all out it's just guessing. That's why you ended up here.
Cold starts:
1. Key to on before cranking causes the fuel pump to run a couple seconds.
2. The PCM looks at the cylinder head temperature and the intake air sensor to set fuel richer, set ignition timing advanced and open the intake air controller.
3. Cranking restarts the fuel pump from the crank sensor signal.
If you don't check each of these functions then you have no idea what's going on.
Could be low fuel pressure from a faulty fuel pump, faulty regulator, intermittent crank sensor. Fuel regulator leaking gas back into the intake causing flooding.
Could be the IAC stuck closed from the last time the motor was run=no idle air.
Faulty CHT, IAT etc.
It's not plugs or coils if it runs otherwise..
Good luck.
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Senior User
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From: Georgia
Thanks for the reply Bluegrass. I was hoping you’d chime in, you’re one of the most knowledgeable on here in my opinion! It was mentioned earlier that there’s a Schrader valve on the fuel rail, can I stick a normal tire pressure gauge on there to test fuel pressure, or what’s the tools/process needed to go about that?
Lead Driver
Joined: Sep 2006
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If you leak any fuel trying a tire gauge, the reading would be questionable.
Should use a fuel gauge with the correct hose attachment.
Operate the ignition 3 times and note the pressure build up and how long it holds after the third time.
Should see about 35 psi and holding 5 to 10 minutes. You can't do that with a tire pressure gauge held in place.
it's possible the regulator is faulty to a point the pressure is way to high. Seen it before. That situation will flood the motor for a no start as the pump is capable of over 80 psi..
Good luck.
Should use a fuel gauge with the correct hose attachment.
Operate the ignition 3 times and note the pressure build up and how long it holds after the third time.
Should see about 35 psi and holding 5 to 10 minutes. You can't do that with a tire pressure gauge held in place.
it's possible the regulator is faulty to a point the pressure is way to high. Seen it before. That situation will flood the motor for a no start as the pump is capable of over 80 psi..
Good luck.
Hotshot
Joined: Jul 2005
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have a tuner in the truck which shows this data and reads DTCs. My coolant temp sensor works fine as far as I can tell. Always seems accurate and goes up to around 200 when the truck warms up
Then you should have fuel pressure readings ???
Then you should have fuel pressure readings ???