390 starting woes
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390 starting woes
I have a 73 F-250 with a 390 that was tuned up six months ago by my mechanic. He put in a new carb which I believe is a Motorcraft 2100. After the tune up the truck ran perfect, very smooth. About a month ago I began to notice after a cold start-up the truck would idle fine and then abruptly quit. It would start back up after quitting just fine. This weekend I can hardly get the truck to start. Initial start-up while cold is good but very soon after the engine stops. If I try to restart I get a lot of dieseling, rough idle, and the engine stops. I also had some white smoke belch out of the carb. My procedure for starting is to give the accelerator a couple of pumps and then crank the key. Any ideas on where to start troubleshooting. I'm no auto mechanic, but I am mechanically inclined.
Senior User
Joined: Aug 2013
Posts: 133
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From: San Diego
One of the first things I did after I got my '73 with 390 was to get a "points eliminator" kit to replace the points and condenser. The Accel kit is about $65 from the parts store and now I never have to worry about re-gapping points periodically.
The kit was unbelievably simple to install and the truck fired up immediately on the first turn when finished. Starting since then has been faultless. It didn't "improve" the performance significanly, but it is definitely more consistent/reliable.
The kit was unbelievably simple to install and the truck fired up immediately on the first turn when finished. Starting since then has been faultless. It didn't "improve" the performance significanly, but it is definitely more consistent/reliable.
Postmaster
Joined: Mar 2011
Posts: 2,698
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From: Taxachusetts
Agree on checking points gap - 0.017" I believe.
Points plate solid? No abnormal play? Distributor wobbly? The hold down bolt snugged up good?
Take the air cleaner off and take a peek down the carb throat....blip the throttle...get a good squirt of gas?
Do you have fuel filters before the fuel pump and after? They in good shape - not gunked up?
Vacuum lines all good and connected?
Choke in good workable condition?
Points plate solid? No abnormal play? Distributor wobbly? The hold down bolt snugged up good?
Take the air cleaner off and take a peek down the carb throat....blip the throttle...get a good squirt of gas?
Do you have fuel filters before the fuel pump and after? They in good shape - not gunked up?
Vacuum lines all good and connected?
Choke in good workable condition?
Logistics Pro
Joined: Jan 2011
Posts: 4,762
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From: Antelope Valley ,CA
if it continues after points condenser change replace the coil , they act real weird when going bad
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Hotshot
Joined: Jul 2005
Posts: 13,834
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From: Middle Tn.
I have a 73 F-250 with a 390 that was tuned up six months ago by my mechanic. He put in a new carb which I believe is a Motorcraft 2100. After the tune up the truck ran perfect, very smooth. About a month ago I began to notice after a cold start-up the truck would idle fine and then abruptly quit. It would start back up after quitting just fine. This weekend I can hardly get the truck to start. Initial start-up while cold is good but very soon after the engine stops. If I try to restart I get a lot of dieseling, rough idle, and the engine stops. I also had some white smoke belch out of the carb. My procedure for starting is to give the accelerator a couple of pumps and then crank the key. Any ideas on where to start troubleshooting. I'm no auto mechanic, but I am mechanically inclined.
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Lead Driver
Joined: Aug 2003
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From: **** hole San Jose ca.
When this little pull off diaphragm fails the chokes stays on full not letting the engine to start up an run. This is on the top of carb just behind the choke butterfly flap.
Remover air filter find the area in reverence i'm talking about then try to starting to motor. Looking between cowl & hood at carb watch the little 90* bent arm on the diaphragm pull down and open the choke plate flap a little. If it's working that is. No movement it's bad. About 12 bucks the last time, I had to buy one.. My 2cents
orich
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I found the problem. I little to no spark and traced it back to bad breaker points. I decided to replace the points with a Crane XR-i as well as some new low resistance plug wires, and new coil. She fired right up with the new parts, runs great. Thanks again for all the suggestions. 
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