1990 Ford Bronco full size 351 hard to start after engine is hot

Topic: 1990 Ford Bronco full size 351 hard to start after engine is hot (Read 4704 times) previous topic - next topic

1990 Ford Bronco full size 351 hard to start after engine is hot

June 17, 2014, 10:34:56 AM

Pulled the 1990 full size bronco 351w with my added 5speed out of moth balls on fathers day.

installed the alternator and battery i had purchased a couple years ago
ran the fuel pump to drain the old gas
added new gas

no leaks, comes down to 800 or so rpm idle.
runs well.
has the egr blocked off but the evp sensor is still hooked up.

start truck many times in a row and it starts well.. when driven it drives great.
when parked it will act exactly like the battery is dead.

let it sit for several hours and the truck starts up fine.

while running i have 14.4v atop the battery.

i shot gunned a few parts yesterday cause i could, put on a new ign switch (all my ign sw wires look like new**!!! interesting.
put on a new starter, new starter relay.

repeated test and truck started perfectly, run it for a long period of time and stop, then it wont start.

let it cool down and it starts.

When i turn off the key, the temp, coolant and oil pres gauges stay put right where they were when running.
When i turn the key forward, they zero out and go down.. not sure what to make of this but first thought was to check for a paracitic draw.
I put a tiny light bulb in line with the neg batt cable and with the key now turned forward, the light does not come on....

any thoughts?>

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #1 – June 17, 2014, 02:27:00 PM

Check your timing and run codes.

once its hot something changes. see what pops up.

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #2 – June 17, 2014, 09:03:16 PM

If you've bumped timing above 10, it can get a little sluggish cranking... My F-250 has been like that on and off for a while, even with a brand new 65-series battery.

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #3 – June 17, 2014, 11:01:08 PM

well, inspected the alternator regulator wiring,, found one conductor that was nicked,, another that looked darkened,, so i cut all three, soldered and heat shrinked them.

to be honest, my batter and alternator have been sitting in the garage for 2 years needing installed ,not that the old units were bad, only that about 3 or so years a go i was fighting this similar issue ,, hell it might have been 4 years ago now that i think about it. last inspection was 2009.

I am thinking the cheapo autozone battery brand isnt going to cut it.
I swapped in my Interstate i950cca from the cougar and the truck "seemed" to crank up a little better while the engine is hot.

again, the issue here is with a bone cold motor it takes nothing to start up the truck.. once heat starts spreading around,, something is causing it to crank very very sluggish.

i put all new starting parts on ,, like i posted in post 1 thinking one of those items were just getting heat soaked.

I am going to take this battery back to autozone,, get my prorated refund then try to find a bigger AH / CCA battery.

Ive always and i mean *ALWAYS* felt like this 351 needed a big ass battery to crank it over.

Its acting backwards to me though.... usually a car cranks hard when the battery is bad and the car has been off for a while. then cranks up fairly easy if you recently ran the car.

in my case.. its hard to start right back up when at normal operating temp..... let things cool down and the thing spins free like a nothings wrong.

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #4 – June 17, 2014, 11:01:31 PM

will check the timeing,, ran out of light today.....

meant to do that.

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #5 – June 18, 2014, 12:06:05 AM

Ignition module. Pull that puppy and take it to the autohole and have them check it like a dozen times. Most the time they act normal until they get hot, then they start giving you trouble. Have them run the test many times to put some load on it.

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #6 – June 18, 2014, 01:52:34 AM

His cranking is sluggish like a heat soaked starter versus weak ignition.... being that it's a rebuilt auto zone pos I would personally have them test that 50 times and request another....

I once bought a 1 wire alternator from there for a tractor I did a conversion on... The alternator was junk.... took it back explained it wasnt charging. .. they fully stated it was cause the vehicle I bought it for was not in the alternators specs and I voided the warranty. ..
Really a one wire Chevy alternator was never on a 54 ford tractor? Perhaps the alternator was never in half the Chevies it been installed in either. .. for heavens sakes no wonder I stopped shopping at their stores..
Seriously got into one hell of a discussion about how the alternator works...
OReilly s laughed and handed me a working alternator.

In any regards I'm thinking your facing a heat soak issue....

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #7 – June 18, 2014, 07:43:31 PM

Have you done Vdrop on the starter cable? Also, do you have a direct drive starter or a gear reduced unit with it's own solenoid on it?

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #8 – June 19, 2014, 08:11:52 AM

the battery floats at 14.2, alternator at 14.3 to 14.4

as for the starter cable, i had to disconnect it at the starter, then bond it to the other starter relay post to get it hot.... it was at 12.3vdc, with engine off while the battery was at 12.4 with engine off.

timing was at / about 9 or maybe 10 deg BTDC..... i use junk yard crayons to mark zero and 10btdc, white / yellow respectively.

got rid of the autozone batt which has never been used yet but has sat for about 16 months (had decent CCA)
put in an interstate battery and all is well.

problem seems solved...

i shot gunned wayyy too many parts to find this issue. oh well, got some new items on the truck so its not like i wasted money.

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #9 – June 19, 2014, 07:38:12 PM

It honestly sounds like a heat soak on the starter. I had the same problem eons ago in a 71 firebird formula 400.

Also sounds like someone is planning a road trip lol

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #10 – June 19, 2014, 08:34:14 PM

yup,,
New Bethleham
Lockhaven
Eagles Mere
East Palistine
Homestead
all in pa,, all in my 20th (which i just hit 280kmiles....

but the bronco is being summer prep'd as the "adventure wagon" to haul kyak's

but it can come along with me and fetch parts to.... it just drinks so heavy it has a hard time driving straight.

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #11 – June 21, 2014, 12:10:44 AM

Quote from: jcassity;435015

yup,,
but it can come along with me and fetch parts to.... it just drinks so heavy it has a hard time driving straight.

my long lost brother
Major reason I stopped driving roads never went the way they appear. Glad it's fixed

1990 Ford Bronco full size 351 hard to start after engine is hot

Reply #12 – July 16, 2014, 10:00:47 AM

well,,, thought it was fixed.
the higher amp hr battery masked the problem.

after a few days, it dawned on me so checked the smog pulley after warm up, it was tighter than when cold.

1 short belt later to bypass and all seems well.