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Discussion Starter #1
First post. Been reading through archives for a few days, having found this site while trying to solve my problem. Hope to offer my insight wherever I can in the future.

I am the proud owner of one 1978 Bronco Ranger XLT, 351M auto. Had it for over 25 years now, many of which it was the primary mode of transportation. As time went on, it ended up taking on the job of snow plow for the home driveway. Every year I spend an afternoon in the late fall getting her up and running, usually doesn't take much more than some jumper cables and a little patience. This year, not so lucky...

It always takes some coaxing and cranking to get that first start of the year, and this time it took a new battery and a couple of cables to get there. As usual, it finally started and things looked good. Let her warm up for 10 minutes or so (it was cold out) and kicked throttle to knock it off of high idle. When it dropped to curb idle, it just died and hasn't been revived since. That was two weeks ago.

Here's the list of things I have done since:

Rebuilt carb, hadn't been done in 25 years.
New spark plugs
Pulled fuel line at pump inlet, sucked fresh fuel from gas can
New cap and rotor
New ignition module
New coil
New pickup module in distributor

I just don't know what to do next. I have fuel, air, and spark. I havn't done a comp check yet but it acts like it has compression and since it ran just fine for ten minutes before dying I can't imagine it suddenly lost that much. I thought about to possiblity that it jumped a couple teeth, but that just doesn't seem right either. It is definitely winter time here now, and since it's parked outside and won't move, it isn't easy to just start tearing parts off.

The only other "symptoms" I can notice are that sometimes after cranking, it pukes back a decent amount of fuel/air mix from the carb. It's done that for a couple of years now as part of the starting ceremonies. Something a bit more weird is that after cranking it through for a few seconds and then letting off the key, a second or so later it will 'huff' out a half turn or so, like one of the pistons is finishing out a downstroke.

So, where do you knowledgable folks think I should look now? I'm not about to give up, got way too many miles and memories in that drivers seat!
 

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Forward Some Money
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Not sure I understand this:
"Pulled fuel line at pump inlet, sucked fresh fuel from gas can"

I assume you did this to check the pump?
As far as the carb, can you see gas coming from the squirters?

I've never had a 351M, but I've had a '77 302 timing chain set malfunction. It was driving fine, I shut it off to get the mail and it wouldn't start again. Symptoms were similar to what you described.

I'd check your TDC mark (maybe pull a valve cover) and see what's going on with the timing.
 

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yo S,
WELCOME!

Read through fuel system troubleshooting by Recarbco
http://recarbco.com/index.php/tech-help

Look for such Terms as backfire or spitback

such as; "...Hesitation, stalling, stumbling, flat spot, or dead spot during acceleration: Backfiring or spit back up through carb. 1) Vacuum leak. 1) Check for vacuum leak & fix it.
2) Ignition timing retarded too far. 2) Reset timing.
3) Accelerator pump nozzle has dirt in it. 3) Clean out the nozzle tip.
4) Accelerator pump cup swollen up from contact with bad gas or chemicals. 4) Replace the pump cup.
5) Economizer jet too small or partly blocked. 5) Clean out economizer jet & check the size.
6) Choke pull-off open too far. 6) Adjust the pull-off tighter.
7) Secondary throttle plates not closing all the way. 7) Fix it.
8) Vacuum hoses hooked up wrong. 8) Connect up right. Be especially careful of the EGR & Dist. connections: sometimes the pipe locations are reversed on Rochesters.
9) Idle jet partly blocked with dirt. 9) Clean out the jet & any other dirt that is in there.
10) Distributor timing not advancing properly. (worn breaker plate, worn shaft, pin hole in diaphram, crack in hose, etc.) 10) Check distributor and all related systems carefully. Replace defective parts..."


78-79 Emission & Vacuum Diagram Picture Reference by TNT89Bronco at http://fullsizebronco.com/forum/showthread.php?t=205961


Vac leak test by Ryan M at http://web.archive.org/web/20110225113311/http://www.fordfuelinjection.com/?p=93
 

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Discussion Starter #4
Not sure I understand this:
"Pulled fuel line at pump inlet, sucked fresh fuel from gas can"

I assume you did this to check the pump?
As far as the carb, can you see gas coming from the squirters?

I did that just to make sure the fuel I was trying to burn was good. I had left about 5 gallons of treated non-ethanol gas in the tank for 9 months or so, then added another 10 gallons of fresh gas to the tank. Thought it was worth a shot, didn't change anything.

Yeah, there is plenty of gas getting through the carb.

Guess I will check valve timing.
 

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Discussion Starter #5
She started!

It was warmer out this evening than it has been the past few days, so I figured 'why not' and cranked her over. Started without much work at all. Ran like a**, but at least I got somethin to work with!
 
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