im about ready to burn this truck to the ground

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diymirage

diymirage

HP@idle > hondaHP@redline
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as some of you know, i made the mistake of buying a bronco to plow with 2 years ago

in those 2 years, ive had the transmission rebuild, the engine rebuild, the whole stupid truck should be new and dependable

it seems like every time i turn my back to this truck something brakes down

2 weeks ago the ingnition switch went out, so i rewired that

then the alternator went out


now, a few days ago, it has a massive backfire which sucked the choke valve stuck in the in carb throat, so i had to pry it back open with a screw driver
and whatever happened after that i dont know, but it backfires and stalls under load now
i cant even drive the junker around the yard without it dying on me

i pulled the carb off yesterday and found a porous vacuum cap on the back, hoping that was the problem and nope, didnt solve a thing

so, im ready to torch this clunker

577067_274304079355743_2043826958_n.jpg
 
Sounds like it may have blew an intake or carb gasket when it backfired. My brother has a ford ranger that did the same thing a couple months ago. His is a 2001 with a plastic Intake, when it backfired it busted the intake!
 
Mopar-Mitch said:
Sounds like it may have blew an intake or carb gasket when it backfired. My brother has a ford ranger that did the same thing a couple months ago. His is a 2001 with a plastic Intake, when it backfired it busted the intake!
Click to expand...

this is an 87, it has a 351 windsor in it with aluminum intake (edelbrock performer i think)
the intake is definitely still intact and i replace the carb base gasket when i pulled the carb

i was hoping it was just a small vacuum leak, but im not sure what it is, and i just had it with this truck
a brand new engine shouldnt be giving me this much trouble
 
Jadaharabi said:
Flat cam
Click to expand...

checked that, i pulled both valve covers last night and watched all 16 rockers bob their little heads like they should


on a side note, it revs fine in neutral, it only dies under load (when you actually need it to run)
 
Seriously though I think some kind of timing maybe I know I'm just spitballing here but in advance spring popped off inside the distributor? Again it just seems like timings off under load..
 
the truck is pulling 16 inches of vacuum at idle, but without knowing the specs on the cam, that doesnt tell you much


j par said:
Seriously though I think some kind of timing maybe I know I'm just spitballing here but in advance spring popped off inside the distributor? Again it just seems like timings off under load..
Click to expand...

i pulled the rotor cap off and felt the advance lever, there is defintly pressure on there


when i pulled it off though, the center electrode (im sure thats not what its called, but you guys know what i mean) looked burned and brittle

i got a buddy who has terrible taste in trucks and he has one of them HEI caps kicking around, so ill swap that out, probably monday, and see what she does

20190216_132414.jpg


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diymirage said:
the truck is pulling 16 inches of vacuum at idle, but without knowing the specs on the cam, that doesnt tell you much




i pulled the rotor cap off and felt the advance lever, there is defintly pressure on there


when i pulled it off though, the center electrode (im sure thats not what its called, but you guys know what i mean) looked burned and brittle

i got a buddy who has terrible taste in trucks and he has one of them HEI caps kicking around, so ill swap that out, probably monday, and see what she does

View attachment 1715290231

View attachment 1715290232
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understand your frustration the top of that engine looks so clean and to have these kinds of troubles...:BangHead::BangHead:
 
Look under the rotor in the center for a hole. I had one do that to me once.
Just a little hole caused me much grief.


drivin.gif
drive.gif
drivin.gif
 
Under load issues usually stem from vaccum leak/advance, or weak spark/ignition fault.
 
diymirage said:
that is the "one wire" for this one wire distributor
(why the previous owner used that wire, ill never know)

i wrapped some electrical tape around it, and no difference
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Post 12
Those rotors can burn through letting the spark jump right to the metal advance assembly underneath.
From the looks of the button in the cap and the metal contact on the rotor the spark has been jumping around a little.
With a problem like that the spark gets forced to find another path, and does as you add load to the motor.

Most people don't realize it but the higher the cylinder pressure goes, the harder it is for the spark to get to and jump the plug gap.
And especially with HEI it WILL find another place to go.
Normally on that type of distributor that is straight down through the rotor.
 
diymirage said:
now, a few days ago, it has a massive backfire which sucked the choke valve stuck in the in carb throat, so i had to pry it back open with a screw driver
and whatever happened after that i dont know, but it backfires and stalls under load now
i cant even drive the junker around the yard without it dying on me
Click to expand...
diymirage said:
on a side note, it revs fine in neutral, it only dies under load (when you actually need it to run)
Click to expand...
IMO, it didn't suck the choke valve shut, it blew it shut from the bottom. I think this can only mean the plenum had a combustible mixture in it, and it caught fire from a leaky intake valve allowing an already lit cylinder under pressure to force fire into the intake and ignite it. Sure I could be wrong but I think a Compression Test or Leakdown test is in order.
As to the loss of power; if you retimed the ignition after the backfire; this would then point to a jumped chain, and a compression test would find very low compression.
But if the timing remains unchanged, and the idle-speed is not where you last set it, this again points to a jumped chain, or maybe a bent primary butterfly
But if both the timing and the idle-speed remain unchanged, then IDK, unless the low-speed circuit has failed, the secondary plate is not closing properly, or the mains are dribbling.
In any case, if it was mine, and the carb looked good,I think I'd start with a compression test, followed by an LD if the compression is really low. If you suspect a jumped chain, I prove it by checking split overlap, way easier and faster than pulling the front of the engine off.
I really hope I'm wrong, but the loss of power, accompanied by continued backfiring with throttle applied, kindof points in that direction; altho I must admit, the 16inches of vacuum has me puzzled; maybe it's just really lean or trying to burn water. Yeah that could be it!
My condolences; Happy HotRodding,lol.
 
What’s fuel pressure at? What pump and regulator are you using?

Maybe a bad fuel pump?

Just a thought.

Good luck. Eric
 
TrailBeast said:
Post 12
Those rotors can burn through letting the spark jump right to the metal advance assembly underneath.
From the looks of the button in the cap and the metal contact on the rotor the spark has been jumping around a little.
With a problem like that the spark gets forced to find another path, and does as you add load to the motor.

Most people don't realize it but the higher the cylinder pressure goes, the harder it is for the spark to get to and jump the plug gap.
And especially with HEI it WILL find another place to go.
Normally on that type of distributor that is straight down through the rotor.
Click to expand...
I have seen this often. Mostly gm hei.
 
Thanks for all the replies guys, I'm on my way to dinner, I should habe time to give some more indepht awnsers
 
If it backfired that violently, I would be looking for a blown off vacuum hose. A large one. Such as the power brake booster. Or any other large manifold vacuum hose.
 
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