400M will not start when cold
04-05-2009, 12:21 PM
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400M will not start when cold
I recently bought a 78 F-150 4wh dr and this thing will not start if it's below 45 or 50 degrees. Otherwise it starts good. I believe it is a 400M. Has an edelbrock performer intake, and edelbrock carb with electric choke. Motor uses oil, but have not yet checked compression. Timing is set at 4 btdc.
One a good day, with the key off, I press the gas to release the choke, turn the key, and it fires up. Idles ok for about 20 seconds then starts getting real rich. So I then have to play with the gas a little and it runs good.
On a cold day, I do the same process, it fires up and dies. I turn the key to off and when I turn it back to on, the engine will run backwards any where from a half revolution to maybe two revolutions and burps up through the carb quite a bit. (I blew up one starter already).
So I'm wondering if it could be due to compression, or maybe something electrical. It has a Sun tach on it that reads 1000rpm withh the key off, and zero whith it on. Probaby not related, but I'm going to un hook it just to rule it out.
Any advice would be greatly appreciated. Thanks
One a good day, with the key off, I press the gas to release the choke, turn the key, and it fires up. Idles ok for about 20 seconds then starts getting real rich. So I then have to play with the gas a little and it runs good.
On a cold day, I do the same process, it fires up and dies. I turn the key to off and when I turn it back to on, the engine will run backwards any where from a half revolution to maybe two revolutions and burps up through the carb quite a bit. (I blew up one starter already).
So I'm wondering if it could be due to compression, or maybe something electrical. It has a Sun tach on it that reads 1000rpm withh the key off, and zero whith it on. Probaby not related, but I'm going to un hook it just to rule it out.
Any advice would be greatly appreciated. Thanks
04-07-2009, 09:01 PM
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Well by the things you said, i would start by resetting the choke. it sounds like it my need ajusted to open sonner. then i would change the plugs and wires, cap, rotor, then check the firing order you may have a wire crossed, this may be the couse of your burping, then set the timing to 8 bftdc and go from there.
04-07-2009, 09:14 PM
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by the things you said i would think its more then one problem you have. first thing change the plugs,wires,cap,rotor and make shore you check the firing order, you may have a plug wire crossed giving you that little burp. set the choke to open sooner and the timing at 8 bftdc and then go from there,
it sounds like it needs a little tunning
it sounds like it needs a little tunning
04-08-2009, 09:01 AM
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SLR, Thanks for your advise. I did check the firing order, advanced my timing a little more, and leaned out my choke a little more and accidently stumbled accross the problem. I'll descibe it a little in hopes that maybe others can benefit.
I was getting frustrated because it would fire right up, but when I released the key to on, it always died. It would seem to run as long as I kept the starter engaged. By accident, when it died once, I turned the key just a little past on and it fired back up. Apparently, when the switch is cold, the grease inside may inhibit the correct function. Now if I try to start it cold, and it dies, if I turn the switch just past the on position slightly a time or two, it starts right up. So, It turns out to be a bad switch. I went to a boneyard yesterday but could not find a switch with a key. But for now, I am able to start and run it.
I was getting frustrated because it would fire right up, but when I released the key to on, it always died. It would seem to run as long as I kept the starter engaged. By accident, when it died once, I turned the key just a little past on and it fired back up. Apparently, when the switch is cold, the grease inside may inhibit the correct function. Now if I try to start it cold, and it dies, if I turn the switch just past the on position slightly a time or two, it starts right up. So, It turns out to be a bad switch. I went to a boneyard yesterday but could not find a switch with a key. But for now, I am able to start and run it.
04-08-2009, 10:09 AM
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As a young guy, I was always harrassed with, why didn't you do that first? So you dumby, why didn't you. Just kidding, sometimes we all stumble onto the correction, and then stand back and ask ourselves, why didn't I think of that? Congratts and thanks for the answer, am sure others have had or will have the same issue.
04-08-2009, 10:16 AM
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Failed to comment about the heavy choke issue. Wasn't that uncommon back in those days. I currently have a 73 390 and just loves to load up when cold, have played with the unloader adjustment with no help. If I back off the choke more towards lean, then in intermediate weather its difficult to fire up. Thanks goodness she lives in the desert now and just loves the hot weather.
04-08-2009, 10:50 AM
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Hay lean guy
my first was a new 79 bronco XLT with a 400, after 16 years my key chane gatherd a few pounds and after hanging for so long i started having about the same problems you were and i remember calling every one and spending lots of money before i was the one that found the poblem. i steel have my old f150 4x4 i got right after that and had to let go of the bronco witch were in nice condion. and i have seen lots of things mess up on both but they never lift me on the side of the road and every thing on my 79 f150 has been up graded and the 400 is holding around 18 miles to a gaiion if i drive it right. with the help of Tim Meyers piston and crane cams, elderbrock and hardend axls all around. it takes one hack of a chevy truck just to follow me even on the open road. my son has a 04 big horn 4x4 5.7H. i scare him. hold on to it before long youll know every thing about it and you cant drive a new one cheeper then a 79 are 78
my first was a new 79 bronco XLT with a 400, after 16 years my key chane gatherd a few pounds and after hanging for so long i started having about the same problems you were and i remember calling every one and spending lots of money before i was the one that found the poblem. i steel have my old f150 4x4 i got right after that and had to let go of the bronco witch were in nice condion. and i have seen lots of things mess up on both but they never lift me on the side of the road and every thing on my 79 f150 has been up graded and the 400 is holding around 18 miles to a gaiion if i drive it right. with the help of Tim Meyers piston and crane cams, elderbrock and hardend axls all around. it takes one hack of a chevy truck just to follow me even on the open road. my son has a 04 big horn 4x4 5.7H. i scare him. hold on to it before long youll know every thing about it and you cant drive a new one cheeper then a 79 are 78