I have a 92 F150, with the 4.9L. The truck starts great when cold or first thing in the morning. When the truck has been running and is warmed up, imediatly after it is shut off, it will start right back up. However, when it sits for about 5 minutes or more, it will not start up right away. If I turn the key on and off a few times (4-5) so that the fuel pump primes, it will start right up.
I am leaning towards a bad fuel pump, but I would hate to pull it out and do all that work and that no be the problem. I have already replaced the fuel filter.
Any thoughts would be helpfull. It is starting to get worse and I don't want to be left standed somewhere.
My 89 F-150 has a blower that starts to run a few minutes after I shut down a hot engine. It seems to blow air onto the fuel injectors for a short time. I have not discussed this with anyone, but my guess is this cools the injectors and may be to prevent fuel boiling in the fuel rail. I do not know if a 94 has this feature. By the way a 4.9 fuel pressure should be 50 to 60 psi.
I'm pretty sure the blower was only on 88 and 89 I6. My old 89 had the blower which blew air on the injectors and fuel rail. My 92 has no such blower. Maybe Ford trying to prevent vapor lock? The blower is located on the passenger side of the engine compartment somewhere above the charcoal canister.
I have a 89 F-150 4x4 300/6. I bought this truck last year and ever since I've had it it's been hard to start when hot. SHort trip through town it's fine, but after 15 miles or so (when really warmed up) it will not start back up till it sits about 10-20 min. Engine temp is below normal (gauge is fine, just a cool running engine) Voltage is fine, New parts are as follows: Starter(on #7 now), Alternator, battery, all cables, solinoid, ign. switch, timing checked and in spec. new plugs, cap, rotor. This has been a problem since day one. I have put 6 different starters on it to try to remedy the problem all starters are from different stores and still no luck. Heat shields around all exhaust anywhere near the starter. All connections checked and tight corrosion free. Basically the starting and charging system has been replaced. Kind of at a loss here of what the problem may be. There is nothing left to change cause everything is new.
We just put my truck on the neighbors scanner today. Tested everything we could. The Throttle positioning sensor gave no reading, which the neighbor said with his scanner means it is basically shot. I will replace that on Monday and let you know if that does the trick.
couleeman - on my 89 the blower is near the battery and easy to see. Your 92 probably does not have one as I have read than a different heat shielding is used. Do you have headers or any changes that will allow heat from the exhaust to soak into the fuel rail?
This is a long shot,. Years ago to get more power the ignition timing would be advanced. I seem to recall that hot starting problems could result. If the timing is advanced, try retarding it to stock specs.
Yea that has been a question in the back of my mind too, I have a guy bringin a timing light over this week to check it out and see whats up. This weekend while goin huntin I drove 5 miles and changed clothes and ate at mc donalds and went out and had to wait almost an hour for it to start. The wait time for it to start is getting worse everyday. And the engine was not even up to temp this time. It may be the timing has been off for a long time and the starter is just shot from it bein off. So I'll reset the timing and see if it makes a little difference but still might have to get another starter. I'll keep ya all posted.
Will the engine just not start, or will it not even crank? Does it crank fast or slow? If the timing is too far advanced, when hot it will crank very slow and be hard to turn over, like a half dead battery symptom.
No it will not start untill it has sat for about 20 minutes and cooled off after it sits a bit it starts right up no problem. And yes when it is hot it's like the battery is almost dead maybe gets one revolution on the engine then just stops. The cables get hot from trying to start. I am going to be checking the timing tomorrow to see how it is set.
The battery cables might be a problem. They can get corroded from the inside and have a high resistance. That would make it seem like a dead battery when in fact the cables are taking a lot of power away from the start due to thier higher resistance.
The Throttle positioning sensor made a difference, but it still has the problem.
I checked the timing last night. It was right on stock timing. The scanner showed the same thing.
The exaust manifold is stock.
I have replaced both the positive and ground cable. It made no difference.
I can get it to start quite easily by turning the key a couple times just priming the system with the fuel pump. Then it will fire right up. This is why I originally thought it was a fuel pump problem, but when it is cold, it will fire right up, no problem.
It cranks over just fine.
I am going to try putting the stock air intake back on and see if that makes a difference as I have a cold air intake on it now. Trying for a long shot, but I figure that is just time. It could be running to lean.
My engine temp has always run between the N and the O on the gauge. This weekend I will be replacing the plugs, wires, cap and rotor again, as I do have 250000 miles on the existing ones. (put on in January of 2003)
Any other suggestion would be helpfull. It doesn't seem to effect the running, but it is getting annoying when I try to start it after running into the store to buy a pop/