Trouble starting when engine is warm

[Lt.Del]

Doesn't look to tough to take the HEI coil out but how much farther down is the pickup coil? This should be fun.

You can't change the pickup coil while the distributor is installed.

http://www.youtube.com/watch?v=K5QRK9VZwcM&feature=fvwrel

http://www.youtube.com/watch?v=pjivERnPWHw&feature=relmfu

not an HEI, but you get the idea.


this is interesting to test HEI...

http://www.youtube.com/watch?v=ufSoBODtk9Y&NR=1

[devanray]

Choptop; great thoughts. I wonder though if that also would effect performance while driving the vehicle, I've had no problems while it is running, only starting after it warms a bit. And safety tips are ALWAYS welcome. Hope for the best, expect the worst and assume nothing.

I've got new plugs so I'll run some errands tomorrow and wait for it to not start and then check for ignition spark.

SgtDel; replacing that pickup coil looks easy enough, a bit time consuming but not to viscious, haven't finished watching the second vid yet though. That last vid I have actually seen and it makes sense but how would I heat it up? Don't have a heat gun anymore, could use my popcorn popper I suppose 
I'll just test her in the rig for now, probably get wrapped up in a straightjacket if I were caught pointing a popcorn popper and an engine part 

So, tomorrow I will wrap the fuel filter in foil (what the heck right?), pull a plug wire and test for spark when she refuses to start. I'll have the modulator tested and post results.

Fighting Fuel or Fire, I like that.

Thanks all, I truly don't know what I would do without all of your help, except spend tons of $ paying mechanics to guess at what the problem is. So far I've been to two mechanics and it was a waste of time, one told me to get a bracket and a detent cable, this forum taught me that a THM400 doesn't even use a detent cable, just the solenoid and the kickdown switch.

Transmission diagnostics = $150
Engine diag and tune = $170
73-87chevytrucks.com = Priceless

(to be honest, I haven't spent a dime on the mechanics diagnostics but still....)

[devanray]

I could not duplicate the issue today, I did change the plugs this morning while the engine was cold and tested spark with no issues. Idled for 15 minutes and drive for 10, electric fan kicked in so I know temps hit at least 185 degrees. The truck started up every time with no hesitation.

Fuel filter level was almost full this morning and after the drive it went to the red line level in the pic (normal).
Going to go for another drive and get an oil pressure gauge. I'll update if anything changes.

[Irish_Alley]

Next time this happens check your power wire (red) that goes to the cap with the key on. Then check it with someone trying to start the truck

[devanray]

I will do that, yesterday was pretty cold out but today is a bit warmer so I may have a chance to do this. I can't imagine replacing plugs would have solved my issue. below is a few shots of the plugs I pulled out.

[choptop]

I don't see anything unusual with the plugs. Gaps??? The hot fuel issue only showed itself when shut off on a hot day and it sat for 10 minutes or more. If it shut off and immediate restart, no problem occurred. It had to sit long enough for for everything to get hot. As long as fuel is flowing it wouldn't get hot enough to vaporize

[devanray]

Actually the gaps were different, I noticed that the gaps on the new plugs (pregapped) were larger than the old ones. Your symptoms are on the nose with my issue. Ran it on a hot day yesterday and had a tiny amount of issues (compared to before the plug replacement) starting her up. The spark checked out fine, as well as the power to the distributer. I want to say that vaporizing sounds like a good probability.  The fuel filter is about a foot and a half away from the exhaust and has never felt even warm. I still smell fuel and exhaust when exiting my vehicle on a hot day, going to get my coal canister hooked up to the carb soon and see if any difference is made. The exhaust smell may just be normal for a 34 year old vehicle.

How does one take care of vaporising fuel?

[Irish_Alley]

if you wana test for vapor lock then when it acts up again spay starting fluid or carb cleaner into the carb and see it starts. Just to clear up something when it does act up it won’t start at all right? Or does it run rough or what?

[1980c10]

IMO this sounds most likely a coil problem.
you can test your coils by checking for resistance. I don't know the specs but if you have some spare dist laying around you could compare the readings or just look them up somewhere.

[devanray]

I wish I had spare parts of this or that, but I live in a town-home and do all of my work in a parkinglot, pretty much sucks. But, I'd rather work on my 1977 C 10 in a parking lot than my wifes 2005 Ford Escape in a garage

When the vehicle acts up it will not start for about a minute or two before it comes grumbling to life, sputtering white smoke and needing way to much gas pedal to keep it alive. When it gets over that, about 30 seconds or so, it goes up to normal rpm and acts like she should, no problems ever while driving. Just like what ChopTop said

The hot fuel issue only showed itself when shut off on a hot day and it sat for 10 minutes or more. If it shut off and immediate restart, no problem occurred. It had to sit long enough for for everything to get hot. As long as fuel is flowing it wouldn't get hot enough to vaporize

I will have to look up testing coils and find some other data to compare, but honestly, It may be the answer to just get a module and pick-up coil and just rebuilt the dist. The price though comes close to a new one, about $30 diff. What advantage would a new one have over just 'rebuilding' one?

[Irish_Alley]

So its not that it wont start at all just like its getting to much. If its vapor lock it will start only after the fuel cools down.

[choptop]

Ive got two 60 year old vehicles and neither one have the fuel or exhaust smell when i get out, but that does bring something to mind. check the hoses to your inline filter to see if the clamps are loose or if the insides of the hose are cracked. If you smell gas, its not for a good reason. Also if you have an exhaust leak on the right side it will cause alot more heat on that side. Make note of how close the hard line from the fuel pump to the carb is. If it was replaced by a non factory line it may be rerouted to close to the exhaust as well.  Also make sure there arent any signs of fuel leakage around the carb. I actually had a QJET years ago that was acting weird. Saw signs of fuel leakage and found out some of the screws were loose on the carb. Tightened them up and all was well. The guel smell could be the vent not being hooked up to the charcoal canister, but I havent experienced that as an issue. I think f you find the source of the fuel smell youll find the main issue. Gas smell is vaporized fuel, which is hot fuel. Good luck.

[devanray]

It's been a few days since I've had the chance to dig around and follow tubing, but I did drive it yesterday (80 degrees out) and did not have the same issues as before. To start when engine is warm I would just put the pedal down and turn the key, she would crank for a bit and then vroom to life, I slowly let of the gas pedal and she seems fine. I still think I'm having some sort of fuel issue though. I'm going to keep checking things out and see what the fuel pressure is like. How do I test fuel pressure anyways?

[beastie_3]

you can go the the auto store and get a inline fuel psi gauge. I have one and it works just fine.

[devanray]

I'll do that, I'll have to save up some cash since I am already WAY over my budget for this rig. Inline gauge sounds good though, will always be able to see what is going on.