Another carburetor question
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Freshman User
Joined: Nov 2013
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Another carburetor question
Hoping for a few more good responses like I received on my last issue! Thanks again all! 69 F-250 with a recently rebuilt 390. Timing and dwell are spot on. The carburetor is a Motorcraft 2 bbl factory rebuild. I've checked the wet fuel level while warmed up and running and it's good. The motor has not backfired since the rebuild. It started up and has run smoothly since it was first installed. It starts and runs great when it's cold. The problem is when it has been shut down after warming up and I try to start it again. Then it requires a lot of cranking- like it's flooded. However it is not flooded. Also sometimes after it's started and I begin to drive it will stall out and again be difficult to restart. It also stumbles a bit on taking off from a stop or accelerating from a low rpm. No doubt it's something simple I'm overlooking but it has me bumfoozled! Any suggestions would be much appreciated. The old truck has been my primary transportation for 25 years and I'd like to have it healthy again!
Hotshot
Joined: Mar 2013
Posts: 14,255
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From: Phoenix, Az.
Sounds like not enough fuel getting to the carb once the engine is hot. This could be plugged fuel filter, weak fuel pump, or vapor lock. When it stalls I bet if you look down the throat of the carb and work the throttle you won't see the accelerator pump nozzles squirting any gas like they are supposed to.
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Well, it's not the filter and still am not sure about the pump. It is delivering fuel during the slow start-up but it's possible by the time I pull the breather that the pump has recovered. I'm doubting vapor lock. It wasn't a problem prior to the rebuild and this can happen after a 5 mile drive in very cold weather. I believe the pump is getting a good fuel supply judging from the flow when I disconnected it before removing the motor. When I have a few minutes again I'll disconnect the carburetor and pump the gas into a container to see how that goes.
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I just turn the key Rasputin unless I see that it's not going to start. In the beginning I tried about everything knowing I'd have to adjust to a new carburetor. If it hasn't set too long after turning it off it will start right up. After maybe 10 minutes it's anyone's guess what it will do.
New User
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I had a similar issue...turned out to be a bad coil. I thought it was the carb-but as that coil heated up in a few minutes-stall out. Never could tell when it was going to fire up again.
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Thanks for the reply Matson but I don't think it's a coil getting heated up. The truck will always start but at certain times it just takes longer. I've had bad coils in the past too but this is different. Once the truck is running it doesn't stall except once in a great while it will stall shortly after a difficult start-up
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Cargo Master
Joined: Oct 2011
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From: Kenner,La.
hard start
69er, Make sure that the "I" terminal on the solenoid is hot when in cranking mode and that the same voltage is present at the "BAT" side of the coil also.
It also may be caused by the aging of the wiring, it gets frail, just like us.
It also may be caused by the aging of the wiring, it gets frail, just like us.
Hotshot
Joined: Mar 2013
Posts: 14,255
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From: Phoenix, Az.
Well, I'm thinkin' if the fuel delivery system IS getting fuel to the carb then the carb must not be giving it to the engine. You said factory rebuilt. So I'm assuming you bought a rebuilt carb. We don't know why someone had originally taken this carb off their vehicle. You checked fuel (bowl) level and it was correct. So one of the carb's internal passages is holding fuel back when it's hot. The key here seems to be heat. I am also assuming the rebuilt carb came with a real thin gasket that will transmit engine heat to the carb. I would buy a thick carb gasket like the later model vehicles came with and try that. Ford part number was E5HZ9C477A.
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From: Grapevine, TX
I just turn the key Rasputin unless I see that it's not going to start. In the beginning I tried about everything knowing I'd have to adjust to a new carburetor. If it hasn't set too long after turning it off it will start right up. After maybe 10 minutes it's anyone's guess what it will do.
Will keep an eye on this thread to see what you figure out.
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