78 Bronco Hard Starting when warm... - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

bigblockdon · 01-18-2011, 19:35

Im new on the ford forums here and i was wondering if some of you seasoned vets can help. I have a 78 bronco with a 351M. its starts unbelievably well when its cold. but when the engine is warm and i shut it off to talk to someone or do something for 5 minutes the engine won't start again. We've made sure its got spark and fuel. think maybe its the timing chain too far gone and needs replaced? someone suggested putting a manual choke in it. its becoming a more and more reoccuring problem and it is quite frustrating...

**Bert** · 01-18-2011, 20:54

This is the procedure I use to check the chain. Instead of typing it out, I found it online. Timing Chain Slack Test

bigblockdon · 01-19-2011, 04:10

i also forgot to mention that it was used as a plow truck for quite a few years in case that helps. my tech teacher says it sounds like my accelerator pump in my carb and another friend says it sounds like my coil is bad. any takers?

bigblockdon · 01-20-2011, 13:53

Ok well the darn thing is still doing the same exact thing even with a manual choke in it. does anyone have any ideas at all? i need help asap. this truck is my only source of transportation and i need it to be a lil more dependable.... Ignition? timing? anything? throw em out there don't be afraid please!

**Bert** · 01-20-2011, 14:55

Have you checked for spark when this happens? The ignition module or TFI could be the cause.

bigblockdon · 01-20-2011, 18:47

it seems to be getting spark but thats just holding a plug to a ground not with an actual spark tester. but i also noticed something odd. whenever the key is turned from off to on but not start the sparkplugs fire. could that be a symptom? and its now seeming to catch when i let off the key...

**Bert** · 01-20-2011, 18:57

Does it crank at the same speed when it's warm? When you say you have a manual choke now, did you pull the choke all the way on when it wouldn't start to see if that would help? Do have starting fluid or carb cleaner that you could spray in the intake to see if it starts then? Be careful of a fire on a hot engine.

**Bert** · 01-20-2011, 19:35

Is the spark nice and blue when it won't start?

bigblockdon · 01-20-2011, 19:59

not blue but nice strong bright yellow. i found something doing research about the pickup coil, something about the start circuit and run circuit?
78 ford pickup firing problems

could you give it a quick glimpse see what you think? sounds promising to me...

**Bert** · 01-20-2011, 20:08

If it's not a nice blue spark, thats would easily be the problem. It should jump a fairly long gap too. You could do all of those checks they mentioned to see if it helps. The pickup inside the distributor could cause that too.